Vonage 10-K 27 Feb 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	VONAGE HOLDINGS CORP
Entity Central Index Key	1,272,830
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		231,153,342
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,330,553,575

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 31,360	$ 29,078
Marketable securities	0	601
Accounts receivable, net of allowance of $2,258 and $2,093, respectively	44,159	36,688
Inventory, net of allowance of $108 and $117, respectively	2,971	4,116
Deferred customer acquisition costs, current	1,089	2,610
Prepaid Expense, Current	23,763	26,041
Other current assets	6,433	3,147
Total current assets	109,775	102,281
Property and equipment, net of accumulated depreciation of $87,792 and $129,166, respectively	46,754	48,415
Goodwill	373,764	360,363
Software, net of accumulated amortization of $93,858 and $87,626, respectively	22,252	21,971
Restricted cash	1,967	1,851
Intangible assets, net of accumulated amortization of $124,573 and $88,419, respectively	173,270	199,256
Deferred tax assets	110,892	184,210	[1]
Other assets	20,007	17,319
Total assets	858,681	935,666	[1]
Current liabilities:
Accounts payable	29,766	30,751
Accrued expenses	85,410	109,195
Deferred revenue, current portion	30,255	32,442
Current maturities of capital lease obligations	140	3,288
Other Liabilities, Current	156	0
Current portion of notes payable	18,750	18,750
Total current liabilities	164,477	194,426
Indebtedness under revolving credit facility	141,000	209,000
Notes payable, net of debt related cost and current portion	72,765	91,124
Other liabilities	7,541	4,575
Total liabilities	385,783	499,125
Commitments and Contingencies (Note 11)	0	0
Stockholders’ Equity
Common stock, par value $0.001 per share; 596,950 shares authorized at December 31, 2017 and 2016; 298,174 and 282,319 shares issued at December 31, 2017 and 2016, respectively; 230,939 and 219,001 shares outstanding at December 31, 2017 and 2016, respectively	298	282
Additional paid-in capital	1,375,391	1,310,847
Accumulated deficit	(672,561)	(641,869)	[1]
Treasury stock, at cost, 67,235 shares at December 31, 2017 and 63,318 shares at December 31, 2016	(244,239)	(219,125)
Accumulated other comprehensive income/(loss)	14,009	(13,594)
Total stockholders’ equity	472,898	436,541	[1]
Total liabilities and stockholders’ equity	$ 858,681	$ 935,666	[1]
[1]	(1) see Note 3. Correction of Prior Period Financial Statements.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 2,258	$ 2,093
Inventory, allowance	108	117
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	87,792	129,166
Capitalized Computer Software, Accumulated Amortization	93,858	87,626
Finite-Lived Intangible Assets, Accumulated Amortization	$ 124,573	$ 88,419
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized	596,950	596,950
Common stock, shares issued	298,174	282,319
Common stock, shares outstanding	230,939	219,001
Treasury stock, shares	67,235	63,318

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Income Statement [Abstract]
Total revenues	$ 1,002,286	$ 955,621		$ 895,072
Operating Expenses:
Cost of services (excluding depreciation and amortization)	378,960	321,373		261,768
Cost of goods sold	25,994	33,777		34,210
Sales and marketing	313,251	330,969		347,896
Engineering and development	29,630	29,759		27,220
General and administrative	122,537	123,304		109,153
Depreciation and amortization	72,523	72,285		61,833
Operating expenses	942,895	911,467		842,080
Income from operations	59,391	44,154		52,992
Other Income (Expense):
Interest income	17	79		89
Interest expense	(14,868)	(13,042)		(8,786)
Other income/(expense), net	1,253	(346)		(842)
Total other income (expense)	(13,598)	(13,309)		(9,539)
Income from continuing operations before income tax expense	45,793	30,845		43,453
Income tax expense	(79,726)	(17,694)	[1]	(18,418)
(Loss)/income from continuing operations	(33,933)	13,151	[1]	25,035
Loss from discontinued operations	0	0		(1,615)
Loss on disposal, net of taxes	0	0		(824)
Discontinued operations	0	0		(2,439)
Net (loss)/income	(33,933)	13,151	[1]	22,596
Plus: Net loss from discontinued operations attributable to noncontrolling interest	0	0		59
Net (loss)/income attributable to Vonage	$ (33,933)	$ 13,151	[1]	$ 22,655
Net (loss)/income per common share - continuing operations:
Basic net (loss)/income per share - from continuing operations	$ (0.15)	$ 0.06	[1]	$ 0.12
Diluted net (loss)/income per share - from continuing operations	(0.15)	0.06	[1]	0.11
Net loss per common share - discontinued operations attributable to Vonage:
Basic net income per share-from discontinued operations attributable to Vonage (USD per share)	0	0		(0.01)
Diluted net loss per share - from discontinued operations attributable to Vonage	0	0		(0.01)
Net (loss)/income per common share - attributable to Vonage:
Basic net (loss)/income per share - attributable to Vonage	(0.15)	0.06	[1]	0.11
Diluted net (loss)/income per share - attributable to Vonage	$ (0.15)	$ 0.06	[1]	$ 0.10
Weighted-average common shares outstanding:
Basic weighted average common shares outstanding	225,311	215,751		213,147
Diluted weighted average common shares outstanding	225,311	231,941		224,110
[1]	(1) see Note 3. Correction of Prior Period Financial Statements

Consolidated Statements of Inc5

Consolidated Statements of Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Cost of services (excluding depreciation and amortization)	$ 27,308	$ 28,489	$ 24,868

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Other comprehensive income/(loss):
Net (loss)/income	$ (33,933)	$ 13,151	[1]	$ 22,596
Foreign currency translation adjustment, net of tax expense/(benefit)	26,637	(11,937)		1,467
Unrealized loss on available-for-sale securities	1	20		(13)
Unrealized gain on derivatives	965	0		0
Total other comprehensive income/(loss)	27,603	(11,917)		1,454
Comprehensive (loss)/income	(6,330)	1,234	[1]	24,050
Comprehensive income attributable to noncontrolling interest:
Total comprehensive income attributable to noncontrolling interest	0	0		59
Comprehensive (loss)/income attributable to Vonage	(6,330)	1,234	[1]	24,109
Continuing Operations
Other comprehensive income/(loss):
Foreign currency translation adjustment, net of tax expense/(benefit)	26,637	(11,937)		493
Comprehensive income attributable to noncontrolling interest:
Total comprehensive income attributable to noncontrolling interest	0	0		59
Discontinued Operations
Other comprehensive income/(loss):
Foreign currency translation adjustment, net of tax expense/(benefit)	$ 0	$ 0		$ 974
[1]	(1) see Note 3. Correction of Prior Period Financial Statements

Consolidated Statements of Com7

Consolidated Statements of Comprehensive Income Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax	$ 0	$ 0	$ 0
Unrealized Gain on Derivatives, Tax	320	0	0
Continuing Operations
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	4,616	(1,473)	0
Discontinued Operations
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	$ 0	$ 0	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Cash flows from operating activities:
Net (loss)/income	$ (33,933)	$ 13,151	[1]	$ 22,596
Adjustments to reconcile net (loss)/income to net cash provided by operating activities:
Depreciation and impairment charges	34,255	37,651		35,620
Amortization of intangibles	38,056	34,634		26,404
Deferred income taxes	74,577	12,058	[2]	13,949
Change in contingent consideration	0	(16,472)		0
Loss on foreign currency	0	0		1,358
Allowance for doubtful accounts	1,987	1,053		(8)
Allowance for obsolete inventory	412	589		1,882
Amortization of debt related costs	1,074	1,080		997
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	212	0		0
Share-based expense	37,482	40,682		27,541
Noncontrolling interest	(1,879)	0		0
Gain (Loss) on Disposal of Non-controlling Interest	0	0		(907)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(7,253)	(9,642)		185
Inventory	789	800		2,815
Prepaid expenses and other current assets	3,339	(10,182)		(1,904)
Deferred customer acquisition costs	1,729	1,357		421
Accounts payable	(664)	(13,604)		(3,830)
Accrued expenses	(23,361)	6,090	[2]	9,522	[2]
Deferred revenue	(2,584)	(2,126)		(3,682)
Other assets and liabilities	3,820	(3,663)	[2]	(288)	[2]
Net cash provided by operating activities	128,058	93,456	[2]	134,485	[2]
Cash flows from investing activities:
Capital expenditures	(21,915)	(26,146)		(17,323)
Purchase of intangible assets	0	(50)		(2,500)
Purchase of marketable securities	0	(5,664)		(9,982)
Maturities and sales of marketable securities	602	14,991		7,223
Acquisition and development of software assets	(11,374)	(11,538)		(14,183)
Acquisition of business, net of cash acquired	0	(163,042)	[2]	(116,744)	[2]
Proceeds from sale of business	1,950	0		0
Net cash used in investing activities	(30,737)	(191,449)	[2]	(153,509)	[2]
Cash flows from financing activities:
Principal payments on capital lease obligations	(5,788)	(8,583)		(3,549)
Principal payments on notes and revolving credit facility	(101,750)	(72,812)		(47,500)
Proceeds received from draw down of revolving credit facility and issuance of notes payable	15,000	181,250		102,000
Debt related costs	0	(1,316)		(2,007)
Common stock repurchases	(9,542)	(32,902)		(15,911)
Payments Related to Tax Withholding for Share-based Compensation	(15,572)	(6,444)	[2]	(4,754)	[2]
Proceeds from exercise of stock options	21,410	8,861		7,172
Net cash (used in) provided by financing activities	(96,242)	68,054		35,451
Effect of exchange rate changes on cash	1,319	555	[2]	(316)	[2]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect	2,398	(29,384)	[2]	16,111	[2]
Cash and cash equivalents and restricted cash, end of period	31,360	29,078		57,726
Cash, cash equivalents, restricted cash and restricted cash equivalents	$ 33,327	30,929	[2]	60,313	[2]
Accounting Standards Update 2016-09
Changes in operating assets and liabilities, net of acquisitions:
Net cash provided by operating activities		$ 6,444		$ 4,754
[1]	(1) see Note 3. Correction of Prior Period Financial Statements
[2]	(1) See Note 2. Summary of Significant Accounting Policies for reclassification due to the adoptions of new Accounting Standard Updates and Note 3. Correction of Prior Period Financial Statements.

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity and Redeemable Noncontrolling Interest - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Accumulated Deficit		Treasury Stock	Accumulated Other Comprehensive Income	Redeemable Non-controlling interest
Common stock, shares outstanding			211,994
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			5,414
Treasury Stock, Shares, Retired			(919)
Stock Repurchased and Retired During Period, Shares			(3,320)
Stock Issued During Period, Shares, Acquisitions			1,111
Beginning Balance at Dec. 31, 2014	$ 343,497		$ 264	$ 1,184,662	$ (677,675)		$ (159,775)	$ (3,131)	$ (848)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	7,172		5	7,167
Share-based expense	27,541			27,541
Employee taxes paid on withholding shares	(4,754)						(4,754)
Common stock repurchases	(15,250)						(15,250)
Acquisition of business	5,578		1	5,577
Foreign currency translation adjustment, net of tax expense/(benefit)	1,467							1,467
Unrealized loss on available-for-sale securities	(13)							(13)
Unrealized gain on derivatives	0
Net gain (loss)	23,503				22,655				848
Ending Balance at Dec. 31, 2015	388,741		$ 270	1,224,947	(655,020)		(179,779)	(1,677)	0
Common stock, shares outstanding			214,280
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			6,548
Treasury Stock, Shares, Retired			(1,250)
Stock Repurchased and Retired During Period, Shares			(7,400)
Stock Issued During Period, Shares, Acquisitions			6,823
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	8,861		$ 5	8,856
Share-based expense	40,682			40,682
Employee taxes paid on withholding shares	(6,444)						(6,444)
Common stock repurchases	(32,902)						(32,902)
Acquisition of business	36,369		7	36,362
Foreign currency translation adjustment, net of tax expense/(benefit)	(11,937)							(11,937)
Unrealized loss on available-for-sale securities	20							20
Unrealized gain on derivatives	0
Net gain (loss)	13,151				13,151	[1]
Ending Balance at Dec. 31, 2016	$ 436,541	[1]	$ 282	1,310,847	(641,869)	[1]	(219,125)	(13,594)	0
Common stock, shares outstanding	219,001		219,001
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	7,734		15,856
Treasury Stock, Shares, Retired			(2,319)
Stock Repurchased and Retired During Period, Shares			(1,599)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Other	$ 8,909			5,668	3,241
Stock option exercises	21,410		$ 16	21,394
Share-based expense	37,482			37,482
Employee taxes paid on withholding shares	(15,572)						(15,572)
Common stock repurchases	(9,542)						(9,542)
Foreign currency translation adjustment, net of tax expense/(benefit)	26,637							26,637
Unrealized loss on available-for-sale securities	1							1
Unrealized gain on derivatives	965							965
Net gain (loss)	(33,933)				(33,933)
Ending Balance at Dec. 31, 2017	$ 472,898		$ 298	$ 1,375,391	$ (672,561)		$ (244,239)	$ 14,009	$ 0
Common stock, shares outstanding	230,939		230,939
[1]	(1) see Note 3. Correction of Prior Period Financial Statements.

Nature of Business (Notes)

Nature of Business (Notes)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block]	Nature of Business Nature of Operations Vonage Holdings Corp. (“Vonage”, “Company”, “we”, “our”, “us”) is incorporated as a Delaware corporation. We are a leading provider of cloud communications services for businesses. We transform the way people work and businesses operate through a portfolio of cloud-based communications solutions that enable internal collaboration among employees, while also keeping companies closely connected with their customers, across any mode of communication, on any device. For our business customers, we provide innovative, cloud-based Unified Communications as a Service, or UCaaS, solutions, comprised of integrated voice, text, video, data, collaboration, and mobile applications over our flexible, scalable Session Initiation Protocol, or SIP, based Voice over Internet Protocol, or VoIP, network. We also offer Communications Platform as a Service, or CPaaS, solutions designed to enhance the way businesses communicate with their customers by embedding communications into apps, websites and business processes. In combination, our products and services permit our business customers to communicate with their customers and employees through any cloud-connected device, in any place, at any time without the often costly investment required with on-site equipment. We also provide a robust suite of feature-rich residential communication solutions. Customers in the United States represented 85% , 91% , and 95% of our consolidated revenues at December 31, 2017 , December 31, 2016 , and December 31, 2015 , respectively, with the balance in Canada, the United Kingdom, and other countries. Nexmo Inc., or Nexmo, has operations in the United States, United Kingdom, Hong Kong, and Singapore, and provides CPaaS solutions to our customers located in many countries around the world.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation The consolidated financial statements have been prepared in accordance with U.S. GAAP. The Accounting Standards Codification, ASC, established by the Financial Accounting Standards Board, FASB, is the source of authoritative GAAP to be applied to nongovernmental entities. In addition, the rules and interpretive releases of the Securities and Exchange Commission, SEC, under the authority of federal securities laws are also sources of authoritative GAAP for SEC registrants. The consolidated financial statements include the accounts and operations of Vonage and its wholly-owned subsidiaries for which we have a controlling interest. All intercompany balances and transactions have been eliminated in consolidation. The usual condition for a controlling financial interest is ownership of a majority of the voting interests of an entity; however, a controlling financial interest may also exist through arrangements that do not involve controlling voting interests. As such, Vonage applies the guidance of ASC 810, Consolidations , or ASC 810, to determine when an entity that is insufficiently capitalized or not controlled through its voting interests, referred to as a VIE, should be consolidated. In addition, the results of companies acquired or disposed of are included in the consolidated financial statements from the effective date of the acquisition or up to the date of disposal. Revenue Recognition Operating revenues consist of services revenues and customer equipment (which enables our services) and shipping revenues. The point in time at which revenues are recognized is determined in accordance with SEC Staff Accounting Bulletin, SAB, No. 104, Revenue Recognition, and ASC 605, Revenue Recognition . At the time a customer signs up for our services, there are the following deliverables: • Providing equipment, if any, to the customer that enables our telephony services; • Providing services; and • Installation of equipment if required in the contract or terms of service. Activation devices are provided free of charge to our Consumer customers while VOIP enabled phones are provided for a fee to our Business customers. In most instances there are no fees collected at sign-up. We record the fees collected for shipping the equipment to the customer, if any, as shipping and handling revenue at the time of shipment. Services Revenue Substantially all of our revenues are services revenues, which are derived , usage based billion, and, in Vonage Enterprise, we offer domestic and international rate plans, including a variety of residential plans and mobile plans. For consumer customers in the United States, we offer domestic and international rate plans, including a variety of residential plans and mobile plans. For business customers, we offer SMB, mid-market, and enterprise customers several service plans with different pricing structures and contractual requirements ranging in duration from month-to-month to three years. In addition, we provide managed equipment to business customers for which the customers pay a monthly fee. Customers also have the opportunity to purchase premium features for additional fees. We also derive services revenues from per minute fees for international calls if not covered under a plan, including calls made via applications for mobile devices and other stand-alone products, and for any calling minutes in excess of a customer’s monthly plan limits. For a portion of our customers, monthly subscription fees are automatically charged to customers’ credit cards, debit cards or electronic check payments, or ECP, in advance and are recognized over the following month when services are provided. Revenues generated from international calls and from customers exceeding allocated call minutes under limited minute plans are recognized as services are provided, that is, as minutes are used, and are billed to a customer's credit cards, debit cards or ECP in arrears. As a result of multiple billing cycles each month, we estimate the amount of revenues earned from international calls and from customers exceeding allocated call minutes under limited minute plans but not billed from the end of each billing cycle to the end of each reporting period and record these amounts as accounts receivable. These estimates are based primarily upon historical minutes and have been consistent with our actual results. In the United States, we charge regulatory, compliance, E-911, and intellectual property-related fees on a monthly basis to defray costs, and to cover taxes that we are charged by the suppliers of telecommunications services. These charges, along with the remittance to the relevant government entity, are recorded on a net basis. In addition, we collect Federal Universal Service Fund, or USF, fees from customers to recover our obligation to contribute to the fund, as allowed by the FCC. We recognize USF revenues on a gross basis and record the related fees in cost of services. Services revenue also includes supplying messaging (SMS and Voice) services to customers as part of our CPaaS business. Revenue is recognized in the period when messages are sent by the customer. We also transact with providers or bulk SMS aggregators and sell services to these customers who then onsell to their customers. Since the aggregator is our customer, revenue is recognized on a gross basis with related costs included in cost of sales. Customer Equipment and Shipping Revenue Revenue is generated from sales of customer equipment to wholesalers or directly to customers for replacement devices, or for upgrading their device at the time of customer sign-up for which we charge an additional fee. In addition, customer equipment and shipping revenues include revenues from the sale of VoIP telephones in order to access our small and medium business services. Customer equipment and shipping revenues also include the fees that customers are charged for shipping their customer equipment to them. Customer equipment and shipping revenues include sales to our wholesalers, who subsequently resell this customer equipment to customers. Revenues are reduced for payments to wholesalers and rebates to customers to the extent of customer equipment and shipping revenues. Cost of Services Cost of service consists of costs that we pay to third parties such as access and interconnection charges that we pay to other companies to terminate domestic and international phone calls on the public switched telephone network. In addition, costs to lease phone numbers, to co-locate in other companies’ facilities, to provide enhanced emergency dialing capabilities to transmit 911 calls, and to provide local number portability are also included in cost of service. These costs also include taxes that we pay on telecommunications services from our suppliers or are imposed by government agencies such as USF contributions and royalties for use of third parties’ intellectual property. In addition, these costs include certain personnel and related costs for network operations and technical support that are attributable to revenue generating activities. Cost of services excludes depreciation and amortization expense of $27,308 , $28,489 , and $24,868 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Cost of Goods Sold Cost of goods sold consists primarily of costs incurred on customer equipment for customers who subscribe through the direct sales channel in excess of activation fees. The amortization of deferred customer equipment, the cost of shipping and handling for customer equipment, and the cost of certain promotions are also included in cost of goods sold. Sales and Marketing Expenses Sales and marketing expenses consist primarily of personnel and related costs for employees and contractors directly associated with our sales and marketing activities, internet advertising fees, radio and billboard advertising, public relations, commissions paid to employees, resellers and other third parties, trade shows, marketing and promotional activities, customer support, credit card fees, collections, and systems and information technology support. We expense advertising costs during the period in which they are incurred. Advertising costs included in sales and marketing were $57,703 , $75,587 , and $103,320 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Engineering and Development Expenses Engineering and development expenses primarily include personnel and related costs for developers responsible for new products, and software engineers maintaining and enhancing existing products. Research and development costs related to new product development included in engineering and development were $23,730 , $22,447 , and $18,350 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Costs for research, including predevelopment efforts prior to establishing technological feasibility of software expected to be marketed, are expensed as incurred. Development costs are capitalized when technological feasibility has been established and anticipated future revenues support the recoverability of the capitalized amounts. Capitalization stops when the product is available for general release to customers. Due to the short time period between achieving technological feasibility and product release and the insignificant amount of costs incurred during such periods, we have not capitalized any software development, and have expensed these costs as incurred. Restructuring Activities For the year ended December 31, 2017 , we recognized $5,101 of costs associated with restructuring activities included in general and administrative expense. This amount is primarily comprised of costs associated with severance and other employee related costs. As of December 31, 2017, $1,090 remained accrued related to restructuring activities and $4,011 was paid during 2017. Cash, Cash Equivalents and Marketable Securities We maintain cash with several investment grade financial institutions. Highly liquid investments, which are readily convertible into cash, with original maturities of three months or less, are recorded as cash equivalents. Management determines the appropriate classification of our investments in debt and marketable equity securities at the time of purchase and reevaluates such designation at each balance sheet date. Our debt securities have been classified and accounted for as available for sale. In response to changes in the availability of and the yield on alternative investments as well as liquidity requirements, we may sell these securities prior to their stated maturities. These securities are carried at fair value, with the unrealized gains and losses reported as a component of other comprehensive income (loss). Any realized gains or losses on the sale of marketable securities are determined on a specific identification method, and such gains and losses are reflected as a component of other income or expense. Certain Risks and Concentrations Financial instruments that potentially subject us to concentrations of credit risk consist principally of cash equivalents, marketable securities, and accounts receivable. They are subject to fluctuations in both market value and yield based upon changes in market conditions, including interest rates, liquidity, general economic conditions, and conditions specific to the issuers. Accounts receivable are typically unsecured and are derived from revenues earned from customers primarily located in the United States. A portion of our accounts receivable represents the timing difference between when a customer’s credit card is billed and the subsequent settlement of that transaction with our credit card processors. This timing difference is generally three days for substantially all of our credit card receivables. We have never experienced any accounts receivable write-offs due to this timing difference. In addition, we collect subscription fees in advance, minimizing our accounts receivable and bad debt exposure. If a customer’s credit card, debit card or ECP is declined, we generally suspend international calling capabilities as well as their ability to incur domestic usage charges in excess of their plan minutes. Generally, if the customer’s credit card, debit card or ECP could not be successfully processed during three billing cycles, we terminate the account. In addition, we automatically charge any per minute fees to our customers’ credit card, debit card or ECP monthly in arrears. To further mitigate our bad debt exposure, a customer’s credit card, debit card or ECP will be charged in advance of their monthly billing if their international calling or overage charges exceed a certain dollar threshold. Inventory Inventory consists of the cost of customer equipment and is valued at the lower of cost or market, with cost determined using the average cost method. We provide an inventory allowance for customer equipment that has been returned by customers but may not be able to be reissued to new customers or returned to the manufacturer for credit. Property and Equipment Property and equipment includes acquired assets and those accounted for under capital leases and consist principally of network equipment and computer hardware, software, furniture, and leasehold improvements. Company-owned equipment in use at customer premises is also included in property and equipment. Network equipment, computer hardware and furniture are stated at cost with depreciation provided using the straight-line method over the estimated useful lives of the related assets, which range from three to five years. Leasehold improvements are amortized over their estimated useful life of the related assets or the life of the lease, whichever is shorter. The cost of substantial improvements is capitalized while the cost of maintenance and repairs is charged to operating expenses as incurred. Company-owned customer premises equipment is depreciated on a straight-line basis over three years. Our network equipment and computer hardware, which consists of routers, gateways, and servers that enable our services, is subject to technological risks and rapid market changes due to new products and services and changing customer demand. These changes may result in future adjustments to the estimated useful lives or the carrying value of these assets, or both. Software Costs We capitalize certain costs, such as purchased software and internally developed software that we use for customer acquisition and customer care automation tools, in accordance with FASB ASC 350-40, Internal-Use Software . Computer software is stated at cost less accumulated amortization and the estimated useful life is two to five years. Goodwill In accordance with ASC 350, Intangibles - Goodwill and Other , we recognize goodwill for the excess cost of an acquired business over the fair value assigned to assets acquired and liabilities assumed. Goodwill is tested for impairment on an annual basis on October 1st and, when specific circumstances dictate, between annual tests. When impaired, the carrying value of goodwill is written down to fair value. The goodwill impairment test involves evaluating qualitative information to determine if it is more than 50% likely that the fair value of a reporting unit is less than its carrying value. If such a determination is made or if an entity chooses not to perform a qualitative assessment, then the traditional two-step goodwill impairment test described below must be applied. The first step, identifying a potential impairment, compares the fair value of a reporting unit with its carrying amount, including goodwill. If the carrying value of the reporting unit exceeds its fair value, the second step would need to be conducted; otherwise, no further steps are necessary as no potential impairment exists. The second step, measuring the impairment loss, compares the implied fair value of the reporting unit goodwill with the carrying amount of that goodwill. Any excess of the reporting unit goodwill carrying value over the respective implied fair value is recognized as an impairment loss. There was no impairment of goodwill for the years ended December 31, 2017 , 2016 , and 2015 . Intangible Assets Intangible assets acquired in the settlement of litigation or by direct purchase are accounted for based upon the fair value of assets received. Purchased-intangible assets are accounted for based upon the fair value of assets received and are amortized on a straight-line or accelerated basis over the periods of economic benefit, ranging from two to ten years. We perform a review of purchased-intangible assets whenever events or changes in circumstances indicate that the useful life is shorter than we had originally estimated or that the carrying amount of assets may not be recoverable. If such facts and circumstances exist, we assess the recoverability of purchased-intangible assets by comparing the projected undiscounted net cash flows associated with the related asset or group of assets over their remaining lives against their respective carrying amounts. Impairments, if any, are based on the excess of the carrying amount over the fair value of those assets. If the useful life of the asset is shorter than originally estimated, we accelerate the rate of amortization and amortize the remaining carrying value over the new shorter useful life. There was no impairment of purchased-intangible assets identified for the years ended December 31, 2017 , 2016 , and 2015 . Patents and Patent Licenses Patent rights acquired in the settlement of litigation or by direct purchase are accounted for based upon the fair value of assets received. Asset Impairments We evaluate impairment losses on long-lived assets used in operations when events and changes in circumstances indicate that the assets might be impaired. If our review indicates that the carrying value of an asset will not be recoverable, based on a comparison of the carrying value of the asset to the undiscounted future cash flows, the impairment will be measured by comparing the carrying value of the asset to its fair value. Fair value will be determined based on quoted market values, discounted cash flows or appraisals. Impairments of property and equipment are recorded in the statement of income as part of depreciation expense. There was no impairment of property and equipment identified for the years ended December 31, 2017 , 2016 , and 2015 . Debt Related Costs Costs incurred in raising debt are deferred and amortized as interest expense using the effective interest method over the life of the debt. Costs associated with term loans are netted against the underlying notes payable in accordance with ASU 2015-15, "Interest-Imputation of Interest" while costs deferred associated with revolving facilities are included in other assets. Restricted Cash and Letters of Credit We had a cash collateralized letter of credit for $1,563 and $1,578 as of December 31, 2017 and 2016 , respectively, mainly related to lease deposits for our Holmdel office. In the aggregate, cash reserves and collateralized letters of credit of $1,967 and $1,851 were recorded as long-term restricted cash at December 31, 2017 and 2016 , respectively. Derivative Financial Instruments The Company accounts for derivative financial instruments under ASC 815, Derivatives and Hedging, which requires the Company to record all derivatives on the balance sheet at fair value unless they qualify for a normal purchase normal sale exception. Changes in the fair value of non-hedge derivatives are immediately recognized into earnings. Changes in the fair value of derivatives accounted for as hedges, if elected for hedge accounting, are either recognized in earnings as an offset to the changes in the fair value of the related hedged assets and liabilities or deferred and recognized as a component of accumulated other comprehensive income, or OCI, until the hedged transactions occur and are recognized in earnings. During 2017, the Company entered into an interest rate swap to mitigate variability in earnings due to fluctuations in interest rates and has been designated and qualifies as a cash flow hedge. The Company assesses hedge effectiveness under the critical terms matched method at inception and at least quarterly through the life of the hedging relationship. If the critical terms of the interest rate swap match the terms of the forecasted transaction, the Company concludes that the hedge is effective. Income Taxes We recognize deferred tax assets and liabilities at enacted income tax rates for the temporary differences between the financial reporting bases and the tax bases of our assets and liabilities. Any effects of changes in income tax rates or tax laws are included in the provision for income taxes in the period of enactment. Our net deferred tax assets primarily consist of net operating loss carry forwards, or NOLs. We are required to record a valuation allowance against our net deferred tax assets if we conclude that it is more likely than not that taxable income generated in the future will be insufficient to utilize the future income tax benefit from our net deferred tax assets prior to expiration. We periodically review this conclusion, which requires significant management judgment. If we are able to conclude in a future period that a future income tax benefit from our net deferred tax assets has a greater than 50% likelihood of being realized, we are required in that period to reduce the related valuation allowance with a corresponding decrease in income tax expense. This would result in a non-cash benefit to our net income in the period of the determination. In the future, if available evidence changes our conclusion that it is more likely than not that we will utilize our net deferred tax assets prior to their expiration, we will make an adjustment to the related valuation allowance and income tax expense at that time. In subsequent periods, we would expect to recognize income tax expense equal to our pre-tax income multiplied by our effective income tax rate, an expense that was not recognized prior to the reduction of the valuation allowance. Our effective rate may differ from the federal statutory rate due, in part, to our foreign operations and certain discrete period items. On December 22, 2017, the Tax Cuts and Jobs Act, or TCJA, was signed into law by the President of the United States. The TCJA most notably reduces the corporate tax rate from 35% to 21% along with eliminating the alternative minimum tax, or AMT, and imposing a mandatory one-time tax on foreign earnings. Under ASC 740, Income Taxes , an entity is required to recognize the effect of tax law changes during the period of enactment. As such, the Company will be reflecting the impact of this law within its December 31, 2017 financial statements. Due to the complexities of the new legislation and associated accounting considerations, SEC SAB 118 provides for an entity to utilize a provisional estimate within its financial statements for the impact of the TCJA. Based upon currently available information, the Company estimates that the enactment of the legislation will result in a charge to income tax expense of $69,378 which is primarily associated with the re-measurement of the Company’s deferred tax balances at the 21% income tax rate. The Company also reclassified the deferred tax asset related to AMT credits to receivables which are now refundable in the amount of $8,217 , of which $4,108 is included in other current assets as of December 31, 2017. The Company does not currently estimate a material impact associated with the repatriation tax or other facets of the TCJA. Due to the timing of the enactment and the complexity involved in applying the provisions of the TCJA, the Company has made reasonable estimates of the effects and recorded provisional amounts in our financial statements as of December 31, 2017. Additionally, the Company is currently analyzing our global working capital and cash requirements and the potential tax liabilities attributable to a repatriation but we have yet to determine whether we plan to change our prior assessment and repatriate earnings. As such, we have not recorded any deferred taxes attributable to our investments in our foreign entities and will record the tax effects of any change in our prior assertion as we complete our analysis of the TCJA. As we collect further information and interpret the TCJA and any additional guidance issued by the U.S. Treasury Department, the IRS and other regulatory bodies, we may make adjustments to the provisional amounts. The Company will continue to analyze the effects of the TCJA on the Company’s operations and will record any adjustments associated with the enactment of the legislature during the measurement period as provided by SAB 118. The accounting for the impact of the TCJA will be completed in 2018. We file income tax returns in the U.S. for federal and state purposes and in various foreign jurisdictions. Our federal tax return remains subject to examination by the Internal Revenue Service from 2014 to present, our New Jersey tax returns remain open from 2013 to present, our Canada tax return remains open from 2014 to present, and other domestic and foreign tax returns remain open for all periods to which those filings relate. Our Canadian corporate income tax returns for 2012 and 2013 were selected for examination by the Canada Revenue Agency. The Canada Revenue Agency concluded their audit and there were no changes. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution. Business Combinations We account for business combinations using the acquisition method of accounting. The acquisition method of accounting requires that the purchase price, including the fair value of contingent consideration, of the acquisition be allocated to the assets acquired and liabilities assumed using the fair values determined by management as of the acquisition date. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of assets acquired and the liabilities assumed. While the Company uses its best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at the acquisition date, the Company’s estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, the Company records adjustments to the assets acquired and liabilities assumed, with the corresponding offset to goodwill to the extent the Company identifies adjustments to the preliminary purchase price allocation. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations. We include the results of all acquisitions in our consolidated financial statements from the date of acquisition. Acquisition related transaction costs, such as banking, legal, accounting and other costs incurred in connection with an acquisition, are expensed as incurred in general and administrative expense. Acquisition related integration costs include costs associated with exit or disposal activities, which do not meet the criteria of discontinued operations, including costs for employee, lease, and contract terminations, facility closing or other exit activities. Additionally, these costs include expenses directly related to integrating and reorganizing acquired businesses and include items such as employee retention costs, recruiting costs, certain moving costs, certain duplicative costs during integration and asset impairments. These costs are expensed as incurred in general and administrative expense. Acquisition related consideration accounted for as compensation expense, such as restricted cash, restricted stock and option related costs incurred in connection with an acquisition are included in general and administrative expense. Foreign Currency Generally, the functional currency of our non-United States subsidiaries is the local currency. However, the functional currency of Nexmo's United States's subsidiary is the Euro. The financial statements of these subsidiaries are translated to their respective functional currency using month-end rates of exchange for assets and liabilities, and average rates of exchange for revenues, costs, and expenses. Translation gains and losses from the Company's net investments in subsidiaries are deferred and recorded in accumulated other comprehensive income as a component of stockholders’ equity until sale or complete or substantially complete liquidation of the net investment in the foreign entity takes place. Foreign currency transaction gains or losses are reported within other income/(expense) in the Company's consolidated statements of operations. For the years ended December 31, 2017, 2016 and 2015, amounts recognized as foreign currency transaction losses were $620 , $346 and $860 , respectively. Share-Based Compensation We account for share-based compensation in accordance with FASB ASC 718, “Compensation-Stock Compensation”. Under the fair value recognition provisions of this pronouncement, share-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the applicable vesting period of the stock award on a straight-line basis. On January 1, 2017, the Company adopted ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting". Previously, excess tax benefits were recognized in additional paid-in capital on the consolidated balance sheet to the extent they reduced income taxes payable. Beginning in 2017, any excess tax benefits or shortfalls were recorded in the income tax provision upon vest or exercise. During 2017, the Company recorded a net benefit of $11 million related to excess tax benefits. Comprehensive Income Comprehensive income consists of net income (loss) and other comprehensive items. Other comprehensive items include changes in the fair value of derivatives, foreign currency translation adjustments and unrealized gains (losses) on available for sale securities. Use of Estimates Our consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States, which require management to make estimates and assumptions that affect the amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. We base our estimates on historical experience, available market information, appropriate valuation methodologies, and on various other assumptions that we believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Estimates are used for such items as depreciable lives for long-lived assets including intangible assets, tax provisions, uncollectible accounts, and assets and liabilities assumed in business combinations, among others. In addition, estimates are used to test long-lived assets and goodwill for impairment. Reclassifications Reclassifications have been made to our consolidated financial statements for the prior year periods to conform to classification used in the current year period. The reclassifications did not affect results from operations or net assets. Recent Accounting Pronouncements In August 2017, FASB issued ASU 2017-12, "Derivatives and Hedging". The ASU improves the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements and simplifies the application of the hedge accounting guidance in current GAAP. It also amends the disclosures requirements by requiring a tabular disclosure related to the effect on the incomes statement of fair value and cash flow hedges and eliminating the ineffective portion of the change in fa

Correction of Prior Period Fina

Correction of Prior Period Financial Statements (Notes)	12 Months Ended
	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Accounting Changes and Error Corrections [Text Block]	Correction of Prior Period Financial Statements In connection with the preparation of our consolidated financial statements for the quarter ended March 31, 2017, and our remediation efforts related to the material weakness in our internal control over financial reporting related to our controls over the preparation of the annual tax provision, we identified an error as of December 31, 2016 in our recognition of a deferred tax asset related to contingent consideration with vesting requirements paid in connection with the acquisition of Nexmo. Based in part upon the vesting requirements of contingent consideration, we recorded the consideration as compensation expense in general and administrative expense in our consolidated statements of operations. However, for tax purposes the contingent consideration should have been recorded as merger consideration and not deductible compensation. The correction of this error requires the reversal of the deferred tax asset on the consolidated balance sheets and related tax benefits of $4,756 as of December 31, 2016. In accordance with SAB No. 99, Materiality, and SAB No. 108, Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements, we evaluated the error and determined that the related impact was not material to our results of operations or financial position for any prior annual or interim period, but that correcting the $4,756 cumulative impact of the error would be material to our results of operations for the three months ended March 31, 2017. Accordingly, we have corrected the consolidated balance sheets as of December 31, 2016 and have corrected this error in all prior periods presented by revising the appropriate consolidated financial statements. The impact to the consolidated balance sheet as of December 31, 2016 and the consolidated statements of income for the three months and year ended December 31, 2016 is as follows: Consolidated Balance Sheets As of December 31, 2016 As Reported Adjustment As Revised Deferred tax assets, non-current $ 188,966 $ 4,756 $ 184,210 Total assets 940,422 4,756 935,666 Accumulated deficit (637,113 ) 4,756 (641,869 ) Total stockholders' equity 441,297 4,756 436,541 Total liabilities and stockholders' equity 940,422 4,756 935,666 Consolidated Statements of Operations Three Months Ended December 31, 2016 Year Ended December 31, 2016 (Unaudited) As Reported Adjustment As Revised As Reported Adjustment As Revised Income tax expense $ (1,553 ) $ 2,039 $ (3,592 ) $ (12,938 ) $ 4,756 $ (17,694 ) Net income 1 2,039 (2,038 ) 17,907 4,756 13,151 Net income per common share: Basic $ — $ 0.01 $ (0.01 ) $ 0.08 $ 0.02 $ 0.06 Diluted $ — $ 0.01 $ (0.01 ) $ 0.08 $ 0.02 $ 0.06

Earnings Per Share (Notes)

Earnings Per Share (Notes)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Net income or loss per share has been computed according to FASB ASC 260, “Earnings per Share”, which requires a dual presentation of basic and diluted earnings per share, or EPS. Basic EPS represents net income or loss divided by the weighted average number of common shares outstanding during a reporting period. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock, including stock options and restricted stock units under our 2001 Stock Incentive Plan and 2006 Incentive Plan were exercised or converted into common stock. The dilutive effect of outstanding, stock options and restricted stock units is reflected in diluted earnings per share by application of the treasury stock method. In applying the treasury stock method for stock-based compensation arrangements, the assumed proceeds are computed as the sum of the amount the employee must pay upon exercise and the amounts of average unrecognized compensation cost attributed to future services. The following table sets forth the computation for basic and diluted net income per share: For the years ended December 31, 2017 2016 2015 (Revised) (1) Numerator (Loss)/income from continuing operations $ (33,933 ) $ 13,151 $ 25,035 Discontinued operations — — (2,439 ) Plus: Net loss from discontinued operations attributable to noncontrolling interest — — 59 Loss from discontinued operations attributable to Vonage — — (2,380 ) Net (loss)/income attributable to Vonage $ (33,933 ) $ 13,151 $ 22,655 Denominator Basic weighted average common shares outstanding 225,311 215,751 213,147 Dilutive effect of stock options and restricted stock units — 16,190 10,963 Diluted weighted average common shares outstanding 225,311 231,941 224,110 Basic net (loss)/income per share Basic net (loss)/income per share - from continuing operations $ (0.15 ) $ 0.06 $ 0.12 Basic net loss per share - from discontinued operations attributable to Vonage — — (0.01 ) Basic net (loss)/income per share - attributable to Vonage $ (0.15 ) $ 0.06 $ 0.11 Diluted net income per share Diluted net (loss)/income per share - from continuing operations $ (0.15 ) $ 0.06 $ 0.11 Diluted net loss per share - from discontinued operations attributable to Vonage — — (0.01 ) Diluted net (loss)/income per share - attributable to Vonage $ (0.15 ) $ 0.06 $ 0.10 (1) see Note 3. Correction of Prior Period Financial Statements The following shares were excluded from the calculation of diluted income per share because of their anti-dilutive effects: For the years ended December 31, 2017 2016 2015 Restricted stock units 11,928 8,282 5,827 Employee stock options 10,448 9,030 13,600 22,376 17,312 19,427

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The Company's goodwill is derived primarily from the acquisitions of Vocalocity, Telesphere, iCore, Simple Signal, and Nexmo which are included in the Company's Business segment. The following table provides a summary of the changes in the carrying amounts of goodwill: Balance at January 1, 2016 $ 222,106 Increase in goodwill related to finalization of acquisition accounting for Simple Signal 16 Increase in goodwill related to finalization of acquisition accounting for iCore and immaterial correction of an error discussed further below 2,314 Goodwill recognized for the acquisition of Nexmo on June 3, 2016 143,073 Currency translation adjustments (7,146 ) Balance at December 31, 2016 360,363 Decrease in goodwill related to finalization of acquisition accounting for Nexmo (5,482 ) Currency translation adjustments 18,883 Balance at December 31, 2017 $ 373,764 During the year ended December 31, 2016, the Company recorded an immaterial correction of an error related to the overstatement of certain deferred tax assets recorded in connection with acquisition accounting that were outside of the measurement period. The Company recognized a $2,298 decrease in deferred tax assets, net and a $2,298 increase to goodwill on the consolidated balance sheet as of December 31, 2016. Management performed an evaluation under SAB No. 108 and concluded the effect of the adjustment is immaterial to the current period’s financial statements. The correction of the error did not have an effect on our consolidated statements of operations or on our consolidated statements of cash flows for the year ended December 31, 2016. The performance of the Company's annual impairment analysis did not result in any impairments of goodwill for the years ended December 31, 2017, 2016 and 2015, respectively. Intangible assets, net The Company's intangible assets as of December 31, 2017 and 2016 primarily reflect intangible assets established with the acquisitions of various companies such as customer relationships, trade names and developed technology. In addition, the Company's intangible assets include patents we have purchased and licensed, including in connection with the settlement of litigation. December 31, 2017 December 31, 2016 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value Customer relationships 7 to 12 years $ 184,465 $ (62,072 ) $ 122,393 $ 173,187 $ (39,413 ) $ 133,774 Developed technology 3 to 10 years 90,417 (44,413 ) 46,004 88,609 (31,364 ) 57,245 Patents and patent licenses 3 to 5 years 20,214 (16,184 ) 4,030 20,214 (14,667 ) 5,547 Trade names 2 to 5 years 1,708 (1,356 ) 352 1,820 (787 ) 1,033 Non-compete agreements 3 years 1,039 (548 ) 491 3,845 (2,188 ) 1,657 Total finite-lived intangible assets 297,843 (124,573 ) 173,270 287,675 (88,419 ) 199,256 During the years ended December 31, 2017 , 2016 and 2015 , the Company recorded amortization expense of $38,056 , $34,634 and $26,404 , respectively. Amortization expense may vary in the future as acquisitions, dispositions and impairments, if any, occur. The total expected future annual amortization for the succeeding five years ended December 31 is as follows: Estimated Amortization Expense 2018 $ 35,747 2019 32,384 2020 27,934 2021 21,985 2022 17,006

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income from continuing operations before income tax expense are as follows: For the years ended December 31, 2017 2016 2015 United States $ 39,370 $ 31,076 $ 38,115 Foreign 6,423 (231 ) 5,338 $ 45,793 $ 30,845 $ 43,453 The income tax provision from continuing operations consisted of the following amounts: For the years ended December 31, 2017 2016 2015 Current: Federal $ (1,101 ) $ (621 ) $ (1,846 ) Foreign (1,731 ) (1,064 ) (1,667 ) State and local taxes (2,317 ) (3,951 ) (956 ) $ (5,149 ) $ (5,636 ) $ (4,469 ) Deferred: Federal $ (75,928 ) $ (12,550 ) $ (11,289 ) Foreign 1,631 2 (1,088 ) State and local taxes (280 ) 490 (1,572 ) (74,577 ) (12,058 ) (13,949 ) $ (79,726 ) $ (17,694 ) $ (18,418 ) The reconciliation between the United States federal statutory rate of 35% to the Company's effective rate is as follows: For the years ended December 31, 2017 2016 2015 U.S. Federal statutory tax rate 35 % 35 % 35 % Permanent items 10 % 10 % 3 % Effect of the Tax Cuts and Jobs Act 152 % — % — % Equity-based compensation (24 )% — % — % State and local taxes, net of federal benefit 5 % 7 % 2 % International tax (reflects effect of losses for which tax benefit not realized) (4 )% — % 1 % Valuation reserve for income taxes and other — % 5 % 2 % Effective tax rate 174 % 57 % 43 % For the year ended December 31, 2017, the Company's overall effective tax rate was different from the statutory rate of 35% primarily due to the impact of tax reform enacted in the United States on December 22, 2017 reducing the corporate tax rate from 35% to 21% beginning January 1, 2018. This resulted in an expense of $69,378 attributable to the re-measurement of the Company's deferred tax assets as of December 31, 2017. The Company does not currently estimate a material impact associated with the repatriation tax or other facets of the TCJA. Due to the timing of the enactment and the complexity involved in applying the provisions of the TCJA, the Company has made reasonable estimates of the effects and recorded provisional amounts in our financial statements as of December 31, 2017. As we collect further information and interpret the TCJA and any additional guidance issued by the U.S. Treasury Department, the IRS and other regulatory bodies, we may make adjustments to the provisional amounts. The Company will continue to analyze the effects of the TCJA on the Company’s operations and will record any adjustments associated with the enactment of the legislature during the measurement period as provided by SAB 118. On January 1, 2017, the Company adopted ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting". Previously, excess tax benefits were recognized in additional paid-in capital on the consolidated balance sheet to the extent they reduced income taxes payable. Beginning in 2017, any excess tax benefits or shortfalls were recorded in the income tax provision upon vest or exercise. During 2017, the Company recorded a net benefit of $11 million related to excess tax benefits. For the year ended December 31, 2016, the Company's overall effective tax rate was different than the statutory rate of 35% primarily due to the permanent adjustment for the contingent consideration relating to the acquisition of Nexmo. For the year ended December 31, 2015, the Company's overall effective tax rate was different than the statutory rate of 35% primarily due to the limitation of the deductibility of compensation expense to certain executives as well as costs related to the acquisitions which occurred during the year. The temporary differences which gave rise to the Company's deferred tax assets consisted of the following: December 31, 2017 December 31, 2016 Assets and liabilities: Accounts receivable and inventory allowances $ 553 $ 816 Deferred rent 862 630 Contingent consideration — 1,482 Acquired intangible assets and property and equipment (39,077 ) (61,486 ) Accrued expenses 5,182 10,145 Research and development and alternative minimum tax credit 958 8,039 Stock option compensation 17,734 24,026 Capital leases 37 (7,762 ) Cumulative translation adjustments (714 ) — Deferred revenue 6,994 11,362 Derivatives (319 ) — Net operating loss carryforwards 141,072 215,504 133,282 202,756 Valuation allowance (22,390 ) (18,546 ) Deferred tax assets, net, non-current $ 110,892 $ 184,210 Deferred tax assets and valuation allowance Net deferred tax balance - As of December 31, 2017 and 2016, Vonage recorded a net deferred tax asset of $110,892 and $184,210 , respectively. The Company believes that the net deferred tax assets related to its United Kingdom subsidiary Vonage Limited may not be realizable under a "more likely than not" measurement and as such, a valuation allowance has been established to reduce the asset accordingly. NOL carryforwards - As of December 31, 2017, the Company has U.S. Federal and state NOL carryforwards of $556,368 and $146,254 , respectively, which expire at various times through 2037. We have NOLs for United Kingdom tax purposes of $50,142 with no expiration date. Under Section 382 of the Internal Revenue Code, if we undergo an “ownership change” which is generally defined as a greater than 50% change by value in our equity ownership over a three-year period, our ability to use our pre-change of control NOLs and other pre-change tax attributes against our post-change income may be limited. The Section 382 limitation is applied annually so as to limit the use of our pre-change NOLs to an amount that generally equals the value of our stock immediately before the ownership change multiplied by a designated federal long-term tax-exempt rate. At December 31, 2017 , there were no limitations on the use of our NOLs except for certain of the NOLs of Vocalocity as of the date of acquisition for which the Company has reflected in the deferred tax asset. Valuation Allowance - As of December 31, 2017, the Company's tax effected valuation allowance was $22,390 , primarily consisting of NOLs associated with Vonage Limited and state NOLs for certain legal entities. Uncertain tax benefits The Company had uncertain tax benefits of $1,086 and $0 as of December 31, 2017 and 2016, respectively. The Company recognizes interest and penalties related to uncertain tax benefits in income tax expense. The Company did not have any interest or penalties related to these uncertain tax benefits as of December 31, 2017 and 2016. The following table reconciles the total amounts of uncertain tax benefits: As of December 31, 2017 2016 Balance as of January 1 $ — — Increase due to current year positions 1,086 — Uncertain tax benefits as of December 31 $ 1,086 $ — Tax jurisdictions Business is conducted in various countries throughout the world and is subject to tax in numerous jurisdictions. A significant number of tax returns that are filed are subject by various Federal, state and local tax authorities. The Company is no longer subject to U.S. federal income tax examinations for years prior to 2014. With few exceptions, state and local income tax examinations are no longer open for years before 2013.

Long-Term Debt and Revolving Cr

Long-Term Debt and Revolving Credit Facility	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt And Revolving Credit Facility	Long-Term Debt and Revolving Credit Facility A schedule of long-term debt at December 31, 2017 and 2016 is as follows: December 31, 2017 December 31, 2016 2.50-3.25% Term note - due 2020, net of debt related costs 72,765 91,124 2.50-3.25% Revolving credit facility - due 2020 141,000 209,000 Total long-term debt and revolving credit facility $ 213,765 $ 300,124 As our credit facility described below matures in 2020, there are no future anticipated payments of debt obligations beyond June 3, 2020. As of December 31, 2017 , future payments under long-term debt obligations over each of the next three years are as follows: 2016 Credit Facility 2018 18,750 2019 18,750 2020 195,687 Minimum future payments of principal 233,187 Less debt issuance costs 672 Current portion of long-term debt 18,750 Long-term debt and revolving credit facility $ 213,765 2016 Financing On June 3, 2016, we entered into Amendment No. 1 to the Amended and Restated Credit Agreement, or the 2016 Credit Facility, consisting of a $125,000 term note and a $325,000 revolving credit facility. The co-borrowers under the 2016 Credit Facility are the Company and Vonage America Inc., the Company’s wholly owned subsidiary. Obligations under the 2016 Credit Facility are guaranteed, fully and unconditionally, by the Company’s other United States material subsidiaries and are secured by substantially all of the assets of each borrower and each guarantor. The loans under the 2016 Credit Facility mature in June 2020. Principal amounts under the 2016 Credit Facility are repayable in quarterly installments of approximately $4,688 for the term note. The unused portion of our revolving credit facility incurs a 0.45% commitment fee. Such commitment fee will be reduced to 0.40% if our consolidated leverage ratio is greater than or equal to 1.50 to 1.00 and less than 2.50 to 1.00, 0.375% if our consolidated leverage ratio is greater than or equal to 0.75 to 1.00 and less than 1.50 to 1.00, and to 0.35% if our consolidated leverage ratio is less than 0.75 to 1.00. We may prepay the 2016 Credit Facility at our option at any time without premium or penalty. The 2016 Credit Facility includes customary representations and warranties and affirmative covenants of the borrowers. In addition, the 2016 Credit Facility contains customary negative covenants, including, among other things, restrictions on the ability of us and our subsidiaries to consolidate or merge, create liens, incur additional indebtedness, dispose of assets, consummate acquisitions, make investments, and pay dividends and other distributions. As of December 31, 2017 , we were in compliance with all covenants, including financial covenants, for the 2016 Credit Facility. Outstanding amounts under the 2016 Credit Facility, at our option, will bear interest at: • LIBOR (applicable to one-, two-, three-, six-, or twelve-month periods) plus an applicable margin equal to 2.50% if our consolidated leverage ratio is less than 0.75 to 1.00, 2.75% if our consolidated leverage ratio is greater than or equal to 0.75 to 1.00 and less than 1.50 to 1.00, 3.00% if our consolidated leverage ratio is greater than or equal to 1.50 to 1.00 and less than 2.5 to 1.00, and 3.25% if our consolidated leverage ratio is greater than or equal to 2.50 to 1.00, payable on the last day of each relevant interest period or, if the interest period is longer than three months, each day that is three months after the first day of the interest period, or • the base rate determined by reference to the highest of (a) the prime rate of JPMorgan Chase Bank, N.A., (b) the federal funds effective rate from time to time plus 0.50% , and (c) the adjusted LIBO rate applicable to one month interest periods plus 1.00% , plus an applicable margin equal to 1.50% if our consolidated leverage ratio is less than 0.75 to 1.00, 1.75% if our consolidated leverage ratio is greater than or equal to 0.75 to 1.00 and less than 1.50 to 1.00, 2.00% if our consolidated leverage ratio is greater than or equal to 1.50 to 1.00 and less than 2.50 to 1.00, and 2.25% if our consolidated leverage ratio is greater than or equal to 2.5 to 1.00, payable on the last business day of each March, June, September, and December and the maturity date of the 2016 Credit Facility. Use of Proceeds We used $197,750 of the net available proceeds of the 2016 Credit Facility to retire all of the debt under the credit facility entered into in 2015. We used $179,000 from our 2016 Credit Facility in connection with the acquisition of Nexmo on June 3, 2016. Remaining proceeds from the term note and the undrawn revolving credit facility under the 2016 Credit Facility will be used for general corporate purposes. We also incurred fees of $1,316 in connection with the 2016 Credit Facility, of which $395 was allocated to the term note and $921 was allocated to the revolving credit facility. The unamortized fees of $2,740 in connection with the 2015 Credit Facility were allocated as follows: $930 to the term note and $1,810 to the revolving credit facility. These fees were amortized to interest expenses over the life of the debt using the effective interest method for the term note and straight line method for the revolving credit facility. Repayments In 2017 , we made mandatory repayment of $18,750 under the term note. In addition, we repaid the $83,000 outstanding under the revolving credit facility. Interest Rate Swap On July 14, 2017, we executed on three interest rate swap agreements in order to hedge the variability of expected future cash interest payments related to the 2016 Credit Facility. The swaps have an aggregate notional amount of $150 million and were effective on July 31, 2017 through June 3, 2020 concurrent with the term of the 2016 Credit Facility. Under the swaps our interest rate is fixed at 4.7% . The interest rate swaps are accounted for as cash flow hedges in accordance with ASC 815, Derivatives and Hedging . As of December 31, 2017, the fair market value of the swaps was $1,285 , which is included in other assets and accumulated OCI on the face of our consolidated balance sheet. As of December 31, 2017, the critical terms of the swap agreements have not changed and therefore, there is no ineffectiveness to be recorded and all changes in the fair value of the interest rate swaps are recorded in accumulated OCI. The following table summarizes the effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow derivatives: Year Ended December 31 2017 Accumulated OCI beginning balance $ — Mark-to-market of cash flow hedge accounting contracts 965 Accumulated OCI ending balance, net of tax of $320 $ 965 Gains expected to be realized from accumulated OCI during the next 12 months $ —

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments ASC 820-10 defines fair value as the amount that would be received for an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. ASC 820-10 also establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. ASC 820-10 describes the following three levels of inputs that may be used: • Level 1: Quoted prices (unadjusted) in active markets that are accessible at the measurement date for identical assets and liabilities. The fair value hierarchy gives the highest priority to Level 1 inputs. • Level 2: Observable prices that are based on inputs not quoted on active markets but corroborated by market data. • Level 3: Unobservable inputs when there is little or no market data available, thereby requiring an entity to develop its own assumptions. The fair value hierarchy gives the lowest priority to Level 3 inputs. Although management believed its valuation methods were appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could have resulted in a different fair value measurement at the reporting date. The following table presents the assets and liabilities that are measured and recognized at fair value on a recurring basis classified under the appropriate level of the fair value hierarchy as of December 31, 2017 and December 31, 2016 : December 31, 2017 December 31, 2016 Level 1 Measurements Money market fund (1) $ — $ 300 Level 2 Measurements Available-for-sale securities (2) $ — $ 601 Interest rate swaps (3) $ 1,285 $ — (1) Included in cash and cash equivalents on our consolidated balance sheet. (2) Included in marketable securities on our consolidated balance sheet. (3) Included in other liabilities on our consolidated balance sheet. Fair Value of Other Financial Instruments The carrying amounts of our financial instruments, including cash and cash equivalents, accounts receivable, and accounts payable, approximate fair value and are classified as Level 1 because of their short maturities. The carrying amounts of our capital leases approximate fair value of these obligations based upon management’s best estimates of interest rates that would be available for similar debt obligations at December 31, 2017 and 2016 . We believe the fair value of our debt at December 31, 2017 and December 31, 2016 were approximately the same as their carrying amounts as market conditions, including credit spread relative to our credit rating, and illiquidity, remain relatively unchanged from the issuance date of our debt on June 3, 2016 for a similar debt instrument and are classified as Level 3 within the fair value hierarchy. As of December 31, 2017 , we did not have any other assets or liabilities that are measured and recognized at fair value on a recurring basis.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Common Stock	Common Stock As of December 31, 2017 and December 31, 2016, the Company had 596,950 shares of common stock authorized. For a detailed description of our share-based compensation programs refer to Note 10, Employee Stock Benefit Plans. Common Stock Repurchases On December 9, 2014, Vonage's Board of Directors authorized a program for the Company to repurchase up to $100,000 of its outstanding common stock, or the 2014 $100,000 repurchase program. Repurchases under the 2014 $100,000 repurchase program are expected to be made over a four -year period ending on December 31, 2018. Under the 2014 $100,000 repurchase program, the timing and amount of repurchases will be determined by management based on its evaluation of market conditions, the trading price of the stock and will vary based on available capital resources and other financial and operational performance, market conditions, securities law limitations, and other factors. Repurchases may be made in the open market or through private transactions from time to time. The repurchases will be made using available cash balances. In any period, under each repurchase program, cash used in financing activities related to common stock repurchases may differ from the comparable change in stockholders' equity, reflecting timing differences between the recognition of share repurchase transactions and their settlement for cash. We repurchased the following shares of common stock with cash resources under the 2014 $100,000 repurchase program as of December 31, 2017 and 2016 : December 31, 2017 December 31, 2016 Shares of common stock repurchased 1,599 7,400 Value of common stock repurchased $ 9,510 $ 32,762 As of December 31, 2017 , $42,533 remained of our 2014 $100,000 repurchase program. The repurchase program expires on December 31, 2018 but may be suspended or discontinued at any time without notice. In any period under the 2014 $100,000 repurchase program, cash used in financing activities related to common stock repurchases may differ from the comparable change in stockholders' equity, reflecting timing differences between the recognition of share repurchase transactions and their settlement for cash. Net Operating Loss Rights Agreement On June 7, 2012, we entered into a Tax Benefits Preservation Plan, or Preservation Plan, designed to preserve stockholder value and tax assets. Our ability to use our tax attributes to offset tax on U.S. taxable income would be substantially limited if there were an "ownership change" as defined under Section 382 of the U.S. Internal Revenue Code. In general, an ownership change would occur if one or more "5-percent shareholders," as defined under Section 382, collectively increase their ownership in us by more than 50 percent over a rolling three-year period. In connection with the adoption of the Preservation Plan, our board of directors declared a dividend of one preferred share purchase right for each outstanding share of the Company’s common stock. The preferred share purchase rights were distributed to stockholders of record as of June 18, 2012, as well as to holders of the Company's common stock issued after that date, but will only be activated if certain triggering events under the Preservation Plan occur. Under the Preservation Plan, preferred share purchase rights will work to impose significant dilution upon any person or group which acquires beneficial ownership of 4.9% or more of the outstanding common stock, without the approval of our board of directors, from and after June 7, 2012. Stockholders that own 4.9% or more of the outstanding common stock as of the opening of business on June 7, 2012, will not trigger the preferred share purchase rights so long as they do not (i) acquire additional shares of common stock or (ii) fall under 4.9% ownership of common stock and then re-acquire shares that in the aggregate equal 4.9% or more of the common stock. The Preservation Plan was initially set to expire no later than the close of business June 7, 2013, unless extended by our board of directors. On June 8, 2017, at the Vonage 2017 annual meeting of stockholders, stockholders ratified the continued extension of the Preservation Plan through June 30, 2019.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Benefit Plans	Employee Stock Benefit Plans Share-Based Compensation Our stock option program is a long-term retention program that is intended to attract, retain and provide incentives for talented employees, officers and directors, and to align stockholder and employee interests. Currently, we grant options from our 2015 Equity Incentive Plan. Our 2006 Incentive Plan was terminated by our board of directors in 2015 and our 2001 Stock Incentive Plan was terminated by our board of directors in 2008. As such, share-based awards are no longer granted under either the 2006 Incentive Plan and the 2001 Stock Incentive Plan. Under the 2015 Equity Incentive Plan, share-based awards can be granted to all employees, including executive officers, outside consultants, and non-employee directors. Vesting periods for share-based awards are generally three or four years for both plans. Awards granted under each plan expire in five or ten years from the effective date of grant. As of April 2010, the Company began routinely granting awards with a ten year expiration period. The fair value for these options was estimated at the date of grant using a Black-Scholes option-pricing model. The assumptions used to value options are as follows: 2017 2016 2015 Risk-free interest rate 1.95-2.18% 1.17-2.12% 1.38-1.80% Expected stock price volatility 46.19-47.59% 47.52-72.50% 73.55-83.14% Dividend yield 0.00 % 0.00 % 0.00 % Expected life (in years) 6.25 6.25 6.25 We estimated the volatility of our stock using historical volatility of our common stock in accordance with guidance in FASB ASC 718, “Compensation-Stock Compensation ”. The risk-free interest rate assumption is based upon observed interest rates appropriate for the term of our employee stock options. The expected term of employee stock options represents the weighted-average period that the stock options are expected to remain outstanding, which we derive based on our historical settlement experience. As we historically have not paid dividends, we utilize a dividend yield of 0% . We also issue restricted performance stock units with vesting that is contingent on both total shareholder return, or TSR, compared to members of our peer group and continued service. For the market-based restricted performance stock units issued during the year ended December 31, 2017 and 2016, the payouts at vesting which are linearly interpolated between the percentiles specified below are as follows: Payout Schedule Percentile Ranking % of Target Earned Greater than 80% 200% 50 % — 80% 100 % — 200% 30 % — 50% 50 % — 100% Less than 30% — % —% Notwithstanding the foregoing, if our TSR is negative for the performance period, then the vesting percentage shall not exceed 100% . In addition, we reduce the shares available for grant to cover the potential payout of 200% . To value these market-based restricted performance stock units, we used a Monte Carlo simulation model on the date of grant. Compensation expense for restricted stock units with performance and market conditions is recognized over the requisite service period using the straight-line method. The assumptions used to value these market based restricted performance stock units are as follows: 2017 2016 2015 Risk-free interest rate 1.54 % 1.12 % 0.98 % Expected stock price volatility 35.99 % 42.61 % 40.21 % Dividend yield 0.00 % 0.00 % 0.00 % Expected term (in years) 2.79 2.79 2.79 Our stock incentive plans as of December 31, 2017 are summarized as follows (in thousands): Shares Authorized Shares Available for Grant Stock Options Outstanding Non-vested Restricted Stock and Restricted Stock Units Options assumed from acquisition 2,227 377 594 685 2006 Incentive Plan 71,669 — 8,576 2,226 2015 Incentive Plan 21,731 11,455 1,278 9,017 Total as of December 31, 2017 95,627 11,832 10,448 11,928 2015 Equity Incentive Plan On June 3, 2015, we adopted our 2015 Equity Incentive Plan which replaced the 2006 Incentive Plan. Shares issued under the plan may be authorized and unissued shares or may be issued shares that we have reacquired. Shares covered by awards that are forfeited, canceled or otherwise expire without having been exercised or settled, or that are settled by cash or other non-share consideration, will become available for issuance pursuant to a new award. Shares that are tendered or withheld to pay the exercise price of an award or to satisfy tax withholding obligations will not be available for issuance pursuant to new awards. Our 2015 Equity Incentive Plan will terminate on June 3, 2025. At December 31, 2017 , 11,455 shares were available for future grant under the 2015 Equity Incentive Plan. The 2015 Equity Incentive Plan permits the grant of stock options, restricted stock, restricted stock units, stock appreciation rights, performance stock, performance units, annual awards, and other awards based on, or related to, shares of our common stock. Options awarded under our 2015 Equity Incentive Plan may be non-qualified stock options or may qualify as incentive stock options under Section 422 of the Internal Revenue Code of 1986, as amended. For purposes of complying with the requirements of Section 162(m) of the Internal Revenue Code of 1986, as amended, the maximum number of shares of common stock that may be subject to stock options, stock appreciation rights, performance-based restricted stock awards, performance-based restricted stock units and performance-based stock awards granted to any participant other than a non-employee director during any calendar year will be limited to 10,000 shares of common stock for each such award type individually. The maximum number of shares of common stock that may be subject to stock options, stock appreciation rights, restricted stock awards, restricted stock units and stock awards granted to any non-employee director during any calendar year will be limited to 10,000 shares of common stock for all such award types in the aggregate. Further, the maximum amount that may become payable to any one Participant during any one calendar year under all Cash Performance Awards intended to qualify as “performance-based compensation” under Section 162(m) of the Internal Revenue Code of 1986, as amended, is limited to $5,000 . Stock Options The following table summarizes the activity and changes related to stock options during the year: Stock Options Outstanding Units Weighted Average Exercise Price Per Unit (in thousands) Outstanding at December 31, 2016 17,580 $ 2.82 Stock options granted 1,022 6.46 Stock options exercised (7,734 ) 2.81 Stock options canceled (420 ) 2.75 Outstanding at December 31, 2017 10,448 $ 3.19 Exercisable at December 31, 2017 7,875 $ 2.78 The weighted average exercise price of options granted was $6.46 , $5.91 , and $4.41 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The aggregate intrinsic value of exercised stock options for the years ended December 31, 2017 , 2016 , and 2015 was $38,958 , $12,142 , and $8,040 , respectively. The weighted average grant date fair market value of stock options granted was $3.04 , $3.01 , and $3.09 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Restricted Stock and Restricted Stock Units The following table summarizes the activity and changes related to restricted stock and restricted stock units during the year: Restricted Stock and Restricted Stock Units Outstanding Units Weighted Average Grant Date Fair Market Value Per Unit (in thousands) Non-vested at December 31, 2016 15,923 5.04 Restricted stocks and restricted stock units granted 6,599 6.79 Restricted stocks and restricted stock units vested (8,145 ) 5.02 Restricted stocks and restricted stock units canceled (2,449 ) 5.16 Non-vested at December 31, 2017 11,928 $ 5.94 The weighted average grant date fair market value of restricted stock and restricted stock units granted was $6.79 , $4.93 , and $5.37 during the year ended December 31, 2017 , 2016 , and 2015 , respectively. The fair value of restricted stock and restricted stock units that vested during the years ended December 31, 2017 , 2016 , and 2015 was $41,057 , $12,248 , and $8,844 , respectively. The aggregate intrinsic value of restricted stock units outstanding was $121,306 as of December 31, 2017 . Supplemental Information Total share-based compensation expense recognized for the years ended December 31, 2017 , 2016 , and 2015 was $37,482 , $40,682 , and $27,541 , respectively, which were recorded to cost of services and general and administrative expense in the consolidated statement of income. As of December 31, 2017 , total unamortized share-based compensation was $29,642 , accounting for forfeitures when they occur, which is expected to be amortized over the remaining vesting period of each grant, up to the next 48 months. Compensation costs for all share-based awards are amortized on a straight-line basis over the requisite service period. Our current policy is to issue new shares to settle the exercise of stock options and prospectively, the vesting of restricted stock units. Information regarding the options outstanding as of December 31, 2017 is summarized below: Stock Options Outstanding Stock Options Exercisable Range of Exercise Prices Stock Options Outstanding Weighted Average Remaining Contractual Life Weighted Average Exercise Price Aggregate Intrinsic Value Stock Options Vested and Exercisable Weighted Average Remaining Contractual Life Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) (in years) (in thousands) (in thousands) (in years) (in thousands) $0.33 to $1.43 2,734 1.32 2,317 1.34 $1.44 to $1.99 12 1.72 12 1.72 $2.00 to $4.00 5,779 3.25 4,773 3.18 $4.01 to $7.34 1,923 5.68 773 4.68 10,448 4.97 3.19 $ 72,950 7,875 3.96 2.78 $ 58,181 Retirement Plan In March 2001, we established a 401(k) Retirement Plan, or the Retirement Plan, available to employees who meet the plan’s eligibility requirements. Participants may elect to contribute a percentage of their compensation to the Retirement Plan up to a statutory limit. We may make a contribution to the Retirement Plan in the form of a matching contribution. The employer matching contribution is 50% of each employee’s contributions not to exceed $6 in 2015 , 2016 , and 2017 . Our expense related to the Retirement Plan was $5,411 , $5,015 , and $3,676 in 2017 , 2016 , and 2015 , respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Capital Leases Assets financed under capital lease agreements are included in property and equipment in the consolidated balance sheet and related depreciation and amortization expense is included in the consolidated statements of operations. On March 24, 2005, we entered into a lease for our headquarters in Holmdel, New Jersey. The overall lease term is twelve years and five months, which ended on August 31, 2017. At the inception of the lease in 2005, we issued a letter of credit which requires $7,350 of cash as collateral, which is classified as restricted cash. A portion of the cash was released, leaving a balance of $1,563 at December 31, 2017 . In November 2015, we entered into the fourth amendment to our headquarters lease effective December 1, 2015. The amendment extends the term of the lease for a period of seventy-four months to commence September 1, 2017 and continue through October 31, 2023. Based on the terms of the lease, it was accounted for as an operating lease when it became effective on September 1, 2017. Operating Leases We have entered into various non-cancelable operating lease agreements for certain of our existing office and telecommunications co-location space in the United States and for international subsidiaries with original lease periods expiring through 2026. We are committed to pay a portion of the buildings’ operating expenses as determined under the agreements. At December 31, 2017 , future payments under capital leases and minimum payments under non-cancelable operating leases are as follows over each of the next five years and thereafter: Capital Leases Operating Leases Committed Sub-lease Income Net Operating Leases 2018 $ 140 $ 12,094 $ (613 ) $ 11,481 2019 — 11,662 (613 ) $ 11,049 2020 — 10,576 (613 ) $ 9,963 2021 — 7,019 (613 ) $ 6,406 2022 — 6,648 (613 ) $ 6,035 Thereafter — 13,403 (409 ) $ 12,994 Total minimum payments required 140 $ 61,402 $ (3,474 ) $ 57,928 Rent expense net of sub-lease income was $11,429 , $7,495 , and $6,378 for the years ended December 31, 2017, 2016 and 2015 , respectively. Stand-by Letters of Credit We have stand-by letters of credit totaling $1,563 and $1,578 , as of December 31, 2017 and 2016 , respectively. End-User Commitments We are obligated to provide telephone services to our registered end-users. The costs related to the potential utilization of minutes sold are expensed as incurred. Our obligation to provide this service is dependent on the proper functioning of systems controlled by third-party service providers. We do not have a contractual service relationship with some of these providers. Vendor Commitments We have several commitments primarily commitments to vendors who will provide local inbound services, provide carrier operation, provide data center with technical supports, provide networks and telephone related services, provide marketing infrastructure and services, provide customer caller ID, provide hardware and software supports, provide web hosting service, provide electricity to our office, and license patents to us. In certain cases, we may terminate these arrangements early upon payment of specified fees. These commitments total $53,650 . Of this total amount, we expect to purchase $38,956 in 2018 , $11,592 in 2019 , $2,106 in 2020 , and $498 in 2021 and 2022, respectively. These amounts do not represent our entire anticipated purchases in the future, but represent only those items for which we are contractually committed. We also purchase products and services as needed with no firm commitment. For this reason, the amounts presented do not provide a reliable indicator of our expected future cash outflows or changes in our expected cash position. Litigation From time to time, in addition to those identified below, we are subject to legal proceedings, claims, investigations, and proceedings in the ordinary course of business, including claims of alleged infringement of third-party patents and other intellectual property rights, commercial, employment, and other matters. From time to time, we also receive letters or other communications from third parties inviting us to obtain patent licenses that might be relevant to our business or alleging that our services infringe upon third party patents or other intellectual property. In accordance with generally accepted accounting principles, we make a provision for a liability when it is both probable that a liability has been incurred and the amount of the loss or range of loss can be reasonably estimated. These provisions, if any, are reviewed at least quarterly and adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel, and other information and events pertaining to a particular case. Litigation is inherently unpredictable. We believe that we have valid defenses with respect to the legal matters pending against us and are vigorously defending these matters. Given the uncertainty surrounding litigation and our inability to assess the likelihood of a favorable or unfavorable outcome in the matters below and our inability to reasonably estimate the amount of loss or range of loss, it is possible that the resolution of one or more of these matters could have a material adverse effect on our consolidated financial position, cash flows or results of operations. IP Matters RPost Holdings, Inc . On August 24, 2012, RPost Holdings, Inc., RPost Communications Limited, and RMail Limited, collectively, RPost, filed a lawsuit against StrongMail Systems, Inc., or StrongMail, in the United States District Court for the Eastern District of Texas alleging that StrongMail’s products and services, including its electronic mail marketing services, are covered by United States Patent Nos. 8,224,913, 8,209,389, 8,161,104, 7,966,372, and 6,182,219. On February 11, 2013, RPost filed an amended complaint, adding 27 new defendants, including Vonage America Inc. RPost’s amended complaint alleges willful infringement of the RPost patents by Vonage and each of the other new defendants because they are customers of StrongMail. StrongMail has agreed to fully defend and indemnify Vonage in this lawsuit. Vonage answered the complaint on May 7, 2013. On September 17, 2015, the Court ordered the consolidation for pre-trial purposes of this case with other cases by RPost. The lead case has been administratively closed and stayed since January 30, 2014 due to multiple pending actions by third parties regarding ownership of the patents at issue. On December 1, 2017, the parties in the consolidated actions filed a joint notice regarding status of the co-pending actions. Plaintiffs requested that the stay be lifted, while defendants maintain that the stay should remain in place. AIP Acquisition LLC . On January 3, 2014, AIP Acquisition LLC, or AIP, filed a lawsuit against Vonage Holdings Corp., Vonage America, Inc., and Vonage Marketing LLC in the U.S. District Court for the District of Delaware alleging that Vonage’s products and services are covered by United States Patent No. 7,269,247. Vonage filed an answer and counterclaims on February 25, 2014. AIP filed an amended complaint on March 18, 2014, which Vonage answered on April 4, 2014. On April 8, 2014, the Court stayed the case pending final resolution of non-party Level 3’s inter partes review request of United States Patent No. 7,724,879, which is a continuation of the ‘247 patent. On October 8, 2014, the Patent Office issued a Final Written Decision, finding all challenged claims of the ‘879 patent to be invalid. On November 10, 2015, the Federal Circuit rejected AIP’s appeal and affirmed the Patent Office’s rejection of the ‘879 patent. Cisco petitioned for inter partes review of the ‘247 patent on November 25, 2014, which was granted on May 20, 2015. On May 18, 2016, the Patent Office issued a Final Written Decision, finding all challenged claims of the ‘247 patent to be invalid. On November 30, 2017, the Federal Circuit rejected another AIP appeal and affirmed the Patent Office's rejection of the '247 patent. On February 22, 2018, AIP’s case was dismissed with prejudice by joint stipulation, with no payment to AIP. Commercial Litigation Merkin & Smith, et al . On September 27, 2013, Arthur Merkin and James Smith filed a putative class action lawsuit against Vonage America, Inc. in the Superior Court of the State of California, County of Los Angeles, alleging that Vonage violated California’s Unfair Competition Law by charging its customers fictitious 911 taxes and fees. On October 30, 2013, Vonage filed a notice removing the case to the United States District Court for the Central District of California. On November 26, 2013, Vonage filed its Answer to the Complaint. On December 4, 2013, Vonage filed a Motion to Compel Arbitration, which the Court denied on February 4, 2014. On March 5, 2014, Vonage appealed that decision to the United States Court of Appeals for the Ninth Circuit. On March 26, 2014, the district court proceedings were stayed pending the appeal. On February 29, 2016, the Ninth Circuit reversed the district court’s ruling and remanded with instructions to grant the motion to compel arbitration. On March 22, 2016, Merkin and Smith filed a petition for rehearing. On May 4, 2016, the Ninth Circuit withdrew its February 29, 2016 decision and issued a new order reversing the district court’s order and remanded with instructions to compel arbitration. The Ninth Circuit also declared as moot the petition for rehearing. On June 27, 2016, the lower court stayed the case pending arbitration. A joint status report was filed with the District Court on December 23, 2016. A second joint status report was filed with the District Court on March 23, 2017. A third joint status report was filed with the District Court on June 27, 2017. A fourth joint status report was filed with the District Court on September 26, 2017. A fifth joint status report was filed with the District Court on December 26, 2017. DSA Promotions, LLC v. Vonage America, Inc. On September 28, 2017, DSA Promotions, LLC, or DSA, filed suit in the District Court of Dallas County, Texas, seeking payment of approximately $162 for goods and materials provided by DSA to Vonage. Vonage was served with the Original Petition and Request for Disclosure on October 13, 2017. DSA makes its claim based upon the doctrine of suit on a sworn account, quantum meruit and unjust enrichment. Vonage removed the matter from Dallas County District Court to the United States Federal Court for the Northern District of Texas, Dallas Division, on November 6, 2017. On November 20, 2017, Vonage filed a motion to transfer venue to New Jersey. On December 4, 2017, DSA filed its response and brief in opposition to the motion to transfer venue. Regulation Telephony services are subject to a broad spectrum of state and federal regulations. Because of the uncertainty over whether Voice over Internet Protocol should be treated as a telecommunications or information service, we have been involved in a substantial amount of state and federal regulatory activity. Implementation and interpretation of the existing laws and regulations is ongoing and is subject to litigation by various federal and state agencies and courts. Due to the uncertainty over the regulatory classification of VoIP service, there can be no assurance that we will not be subject to new regulations or existing regulations under new interpretations, and that such change would not introduce material additional costs to our business. Federal - Net Neutrality Clear and enforceable net neutrality rules make it more difficult for broadband Internet service providers to block or discriminate against Vonage service. In addition, explicitly applying net neutrality rules to wireless broadband Internet service providers could create greater opportunities for VoIP applications that run on wireless broadband Internet service. In December 2010, the Federal Communications Commission, or FCC, adopted net neutrality rules that applied strong net neutrality rules to wired broadband Internet service providers and limited rules to wireless broadband Internet service providers. On January 14, 2014, the D.C. Circuit Court of Appeals vacated a significant portion of the 2010 rules. On May 15, 2014, the FCC issued a Notice of Proposed Rulemaking, or NPRM, proposing new net neutrality rules. After public response to the NPRM, the FCC adopted new neutrality rules on February 26, 2015. These rules prohibit broadband Internet service providers from: (1) blocking or throttling lawful content applications, or services; (2) imposing paid prioritization arrangements; and (3) unreasonably interfering or unreasonably disadvantaging consumers or edge providers. In addition, broadband Internet service providers are required to make certain disclosures regarding their network management practices, network performance, and commercial terms. These net neutrality rules apply the same requirements to wired and wireless broadband Internet service providers. In December 2017, the FCC issued a decision reversing its prior position on net neutrality. The decision allows for paid prioritization. Numerous public interest groups and some companies are currently or expected to challenge the order in court. It is also anticipated that Congress may introduce legislation to overrule the FCC's decision and reinstate net neutrality. Federal - Rural Call Completion Issues On February 7, 2013, the FCC released a NPRM on rural call completion issues. The NPRM proposed new detailed reporting requirements to gauge rural call completion performance. Rural carriers have argued that VoIP provider call completion performance to rural areas is generally poor. On October 28, 2013, the FCC adopted an order on rural call completion imposing new reporting obligations and restricting certain call signaling practices. The call signaling rules went into effect on January 31, 2014. We filed for extensions of the rules, which the FCC granted, and as of April 17, 2014, we were compliant with the FCC call signaling rules. The effective date for the reporting requirements was April 1, 2015. We could be subject to an FCC enforcement action in the future in the event the FCC took the position that our rural call completion performance is inadequate or we were not compliant with the FCC’s order. On June 22, 2017, the FCC issued a Second Further Notice of Proposed Rulemaking. The FCC has proposed changes to the FCC's rules that allegedly would more effectively address rural call completion problems while reducing burdens on covered providers. Vonage reviewed and evaluated the FCC's proposed changes and provided input to The Voice on the Net, or VON, Coalition, an organization that works to advance regulatory policies for IP-enabled communications. Federal - NPRM - Number Slamming On July 13, 2017, the FCC adopted a NPRM regarding ways to protect consumers from number slamming and cramming without impeding competition or impairing the ability of consumers to switch providers. Vonage is monitoring this NPRM. Federal - NPRM Toll Free Assignment Modernization On September 26, 2017 the FCC issued a NPRM regarding the modernization of toll free number assignment. The FCC proposes amending its rules to allow for the use of an auction to assign certain toll free numbers - such as vanity and repeater numbers - in order to better promote the equitable and efficient use of numbers, especially as afforded by the opening of the 833 toll free code. Vonage will continue to monitor activity with respect to this NPRM. Federal - NOI - Enterprise Communications Systems Access to 911 On September 26, 2017, the FCC adopted a Notice of Inquiry, or NOI, with respect to 911 access, routing and location in Enterprise Communication Systems. Vonage continues to monitor activity related to this NOI. Federal - Access to Telecommunication Equipment and Services by Persons with Disabilities At its open meeting scheduled for October 24, 2017, the FCC applied its wireline hearing aid compatibility rules/standards to handsets that provide advanced communication services, which includes interconnected and non-interconnected Voice over IP. The rules include certain coupling and volume control requirements that would allow the handsets to work better for persons with hearing aids. There are also testing and certification requirements, which typically apply to the handset manufacturer. The FCC also adopted a requirement for volume control in wireless handsets. The new rules have a two-year phase in for new phones and do not require the modification to existing handsets. Federal - Rules and Policies Regarding Caller ID Services At its open meeting on October 24, 2017, the FCC issued a report and order regarding amendments to the Commission’s rules to exempt threatening calls from current Caller ID blocking roles so that, among other changes, law enforcement and security personnel have timely access to information they need to aid their investigations. The order exempts threatening calls from the CPN privacy rules. Federal - Part 43 Report and Order At its open meeting scheduled for October 24, 2017, the FCC issued a report and order based on a March 23, 2017 NPRM to eliminate the filing of annual traffic and revenue reports and streamline circuit capacity reports. Federal - Number Portability NPRM and NOI At its open meeting scheduled for October 24, 2017, the FCC released a NPRM that would allow carriers flexibility in conducting number portability database queries to promote nationwide number portability and eliminate the dialing party requirement as it applies to interexchange service. The NOI seeks comments on industry number portability models and how number administration might be improved for more efficient technical, operational, administrative and legal processes. Vonage is working with the VON Coalition and is monitoring this NPRM and NOI. State Telecommunications Regulation In general, the focus of interconnected VoIP telecommunications regulation is at the federal level. On November 12, 2004, the FCC issued a declaratory ruling providing that our service is subject to federal regulation and preempted the Minnesota Public Utilities Commission, or MPUC, from imposing certain of its regulations on us. The FCC's decision was based on its conclusion that our service is interstate in nature and cannot be separated into interstate and intrastate components. On March 21, 2007, the United States Court of Appeals for the 8th Circuit affirmed the FCC's declaratory ruling preempting state regulation of our service. While this ruling does not exempt us from all state oversight of our service, it effectively prevents state telecommunications regulators from imposing certain burdensome and inconsistent market entry requirements and certain other state utility rules and regulations on our service. State regulators continue to probe the limits of federal preemption in their attempts to apply state telecommunications regulation to interconnected VoIP service. On July 16, 2009, the Nebraska Public Service Commission and the Kansas Corporation Commission filed a petition with the FCC seeking a declaratory ruling or, alternatively, adoption of a rule declaring that state authorities may apply universal service funding requirements to nomadic VoIP providers. We participated in the FCC proceedings on the petition. On November 5, 2010, the FCC issued a declaratory ruling that allowed states to assess state USF on nomadic VoIP providers on a going forward basis provided that the states comply with certain conditions to ensure that imposing state USF does not conflict with federal law or policy. More recently on July 28, 2015, the MPUC found that it has authority to regulate Charter’s fixed, interconnected VoIP service. Charter challenged the MPUC’s order at the U.S. District Court for Minnesota. This challenge is currently pending. In September 2017 amicus briefs were filed in support of the Minnesota PUC's appeal of the Charter decision by AARP, the AARP Foundation, Professor Barbara Cherry, the National Association of Regulatory Utility Commissioners and the national Association of State Consumer Advocates and the Mid-Minnesota Legal Aid. On August 14, 2017, the Arizona Corporation Commission issued an opinion and order with respect to amendments to the Arizona Universal Services Fund. The rulemaking allows for, among other things, the collection of additional USF surcharges in Arizona to fund the E-rate Broadband Special Construction Project Matching Fund Program. The Commission held hearings on September 12 and 13, 2017. Vonage will continue to monitor this rulemaking to determine its effect upon its business activities within Arizona. We expect that state public utility commissions and state legislators will continue their attempts to apply state telecommunications regulations to nomadic VoIP service. State and Municipal Taxes In accordance with generally accepted accounting principles, we make a provision for a liability for taxes when it is both probable that a liability has been incurred and the amount of the liability or range of liability can be reasonably estimated. These provisions are reviewed at least quarterly and adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel, and other information and events pertaining to a particular case. For a period of time, we did not collect or remit state or municipal taxes (such as sales, excise, utility, use, and ad valorem taxes), fees or surcharges, or Taxes, on the charges to our customers for our services, except that we historically complied with the New Jersey sales tax. We have received inquiries or demands from a number of state and municipal taxing and 911 agencies seeking payment of Taxes that are applied to or collected from customers of providers of traditional public switched telephone network services. Although we have consistently maintained that these Taxes do not apply to our service for a variety of reasons depending on the statute or rule that establishes such obligations, we are now collecting and remitting sales taxes in certain of those states including a number of states that have changed their statutes to expressly include VoIP. In addition, many states address how VoIP providers should contribute to support public safety agencies, and in those states we remit fees to the appropriate state agencies. We could also be contacted by state or municipal taxing and 911 agencies regarding Taxes that do explicitly apply to VoIP and these agencies could seek retroactive payment of Taxes. As such, we have a reserve of $1,147 as of December 31, 2017 as our best estimate of the potential tax exposure for any retroactive assessment.

Acquisitions and Dispositiions

Acquisitions and Dispositiions	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Acquisition of Business	Acquisitions and Dispositions Sale of Hosted Infrastructure Product Line On May 31, 2017, we completed the sale of our Hosted Infrastructure product line for up to $4.0 million consideration comprised of $1.0 million received upon closing an additional $0.5 million of contingent consideration received during the third quarter and the potential for up to $2.5 million further consideration based on the achievement of financial objectives for net sales during the 18 months following closing. The results of our Hosted Infrastructure product line have been included within the Business segment. As a result of the sale, we recorded a gain of $1,879 within other income for the year ended December 31, 2017. This disposal did not represent a strategic shift in operations and, therefore, did not qualify for presentation as discontinued operations. Acquisition of Nexmo Nexmo Inc. is a global leader in the Communications-Platform-as-a-Service, or CPaaS, segment of the cloud communications market. Nexmo provides innovative communication APIs for text messaging and voice communications, allowing developers and enterprises to embed contextual communications into mobile apps, websites and business workflows via text, social media, chat apps and voice. Pursuant to the Agreement and Plan of Merger dated May 5, 2016 and further amended on June 2, 2016, by and among the Company, Neptune Acquisition Corp., a Delaware corporation and newly formed indirect, wholly owned subsidiary of Vonage, or Merger Sub, Nexmo, a Delaware corporation, and Shareholder Representative Services LLC, a Colorado limited liability company, as representative of the security holders of Nexmo, on June 3, 2016, Merger Sub, on the terms and subject to the conditions thereof, merged with and into Nexmo, and Nexmo became a wholly owned indirect subsidiary of Vonage. Under the agreement, Nexmo shareholders received consideration of $231,122 , with an additional earn-out opportunity, or the "Variable Payout Amount, of up to $20,000 contingent upon Nexmo achieving certain performance targets. Of the consideration, $194,684 (net of cash acquired of $16,094 ) was paid at close, consisting of $163,093 of cash, net of $16,094 of cash acquired, and 6,823 in shares of Vonage common stock valued at $31,591 . The remaining $36,438 of the $231,122 purchase price was in the form of restricted cash, restricted stock and options held by Nexmo management and employees, or the Employee Payout Amount, subject to vesting requirements over time and to be amortized to compensation expense quarterly until vested. The purchase price was subject to adjustments pursuant to the merger agreement for closing cash and working capital of Nexmo, reductions for indebtedness and transaction expenses of Nexmo that remained unpaid as of closing, and escrow fund deposits. The aggregate consideration was allocated among Nexmo equity holders. The consideration was allocated to acquisition cost as follows: Cash paid at closing (inclusive of cash acquired of $16,094) $ 179,186 Stock paid at closing 31,591 Variable Payout Amount (described below) 16,472 Employee Payout Amount (described below) 4,779 Acquisition Cost $ 232,028 In addition, Nexmo shareholders were eligible to earn a Variable Payout Amount of up to $20,000 , subject to the achievement of certain performance targets during the 12 month period following the closing of the transaction. We estimated using probability weighting that the value of the contingent consideration is $17,840 at the acquisition date and included that amount in acquisition cost at the net present value amount of $16,472 . As of December 31, 2016, the Company agreed to a $5,000 settlement in lieu of contingent consideration that could be potentially earned under the purchase agreement for which the parties were paid in the first quarter of 2017. In addition, Nexmo management and employees were eligible to earn an Employee Payout Amount of $36,438 attributable to restricted cash, restricted stock and assumed options, of which $4,779 is included in acquisition cost as service had been provided pre-acquisition and $31,659 was recorded as post-acquisition expense assuming all amounts vest, of which $31,087 was recorded as compensation expense and $572 was recorded as interest expense as continued employment is a condition of receiving consideration. During the years ended December 31, 2017 and 2016, we incurred approximately $0 and $5,500 , respectively in acquisition related transaction costs, which were recorded in general and administrative expense in the accompanying consolidated statements of income. The acquisition was accounted for using the acquisition method of accounting under which assets and liabilities of Nexmo were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. We do not expect any portion of this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition has been recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The factors that contributed to goodwill include synergies that are specific to our consolidated business, the acquisition of a talented workforce that provides us with expertise in the small and medium business markets, as well as other intangible assets that do not qualify for separate recognition. The acquisition price was allocated to the tangible and identified intangible assets acquired and liabilities assumed as of the closing date. The fair values assigned to identifiable intangible assets assumed were based on management’s current estimates and assumptions. The accounting for the Nexmo acquisition was completed during the three months ended June 30, 2017, at which point the fair values became final. The table below summarizes the provisional amounts recognized for assets acquired and liabilities assumed as of December 31, 2016 as well as adjustments made through the year ended December 31, 2017, when the allocation became final. Measurement period adjustments primarily reflect the tax impact of the acquisition date fair values. The table below summarizes the Nexmo assets acquired and liabilities assumed as of June 3, 2016: Acquisition Date Fair Value as of December 31, 2016 Measurement period adjustments Revised Acquisition Date Fair Value Assets Current assets: Cash and cash equivalents $ 16,094 $ — $ 16,094 Accounts receivable 8,764 — 8,764 Prepaid expenses and other current assets 3,507 — 3,507 Total current assets 28,365 — 28,365 Property and equipment 757 — 757 Software, net 242 — 242 Intangible assets 101,770 — 101,770 Restricted cash 51 — 51 Total assets acquired 131,185 — 131,185 Liabilities Current liabilities: Accounts payable 1,841 — 1,841 Accrued expenses 9,299 — 9,299 Deferred revenue, current portion 1,735 — 1,735 Total current liabilities 12,875 — 12,875 Deferred tax liabilities, net, non-current 29,355 (5,482 ) 23,873 Total liabilities assumed 42,230 (5,482 ) 36,748 Net identifiable assets acquired 88,955 5,482 94,437 Goodwill 143,073 (5,482 ) 137,591 Total purchase price $ 232,028 $ — $ 232,028 The intangible assets as of the closing date of the acquisition included: Customer relationships $ 85,900 Developed technologies 13,768 Non-compete agreements 972 Trade names 1,130 $ 101,770 Acquisition of iCore On August 31, 2015 the Company, completed the acquisition of iCore Networks, Inc., or iCore, a provider of cloud-based unified communications and collaboration services, delivering voice, video and mobile communications solutions to business customers to complement the Company's rapidly growing UCaaS business further strengthening the Company's national footprint. The Company acquired iCore for $92,689 in cash consideration, which was subject to adjustments for closing cash and working capital of iCore, reductions for indebtedness and transaction expenses of iCore that remained unpaid as of closing, and escrow fund deposits. The acquisition was accounted for using the acquisition method of accounting under which assets and liabilities of iCore were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. We do not expect any portion of this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition has been recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The table below summarizes the iCore assets acquired and liabilities assumed as of August 31, 2015: Acquisition Date Fair Value Assets Current assets: Cash and cash equivalents $ 1,014 Current assets 2,700 Total current assets 3,714 Property and equipment 4,437 Intangible assets 38,064 Other assets 659 Total assets acquired 46,874 Liabilities Current liabilities: Accounts payable 3,344 Accrued expenses 3,979 Deferred revenue, current portion 576 Current maturities of capital lease obligations 557 Total current liabilities 8,456 Capital lease obligations, net of current maturities 552 Deferred tax liabilities, net, non-current 8,487 Total liabilities assumed 17,495 Net identifiable assets acquired 29,379 Goodwill 63,310 Total purchase price $ 92,689 Acquisition of Simple Signal Pursuant to the Agreement and Plan of Merger dated March 15, 2015, by and among Vonage Holdings Corp., a Delaware corporation, Stratus Acquisition Corp., a California corporation and an indirect wholly owned subsidiary of Parent, or Merger Sub, Simple Signal Inc., a California corporation, or Simple Signal, and Simplerep, LLC, a Colorado limited liability company, as representative of the security holders of Simple Signal, on April 1, 2015, Merger Sub merged with and into Simple Signal, and Simple Signal became a wholly owned indirect subsidiary of Vonage. Simple Signal provides cloud-based unified communications and collaboration services, delivering voice, video, and mobile communications solutions to business customers. Simple Signal is a natural complement to our expanding UCaaS business. We acquired Simple Signal for $25,578 , including 1,111 shares of Vonage common stock (which shares had an aggregate value of approximately $5,578 based upon the closing stock price on April 1, 2015) and cash consideration of $20,000 , subject to adjustments pursuant to the merger agreement for closing cash and working capital of Simple Signal, reductions for indebtedness and transaction expenses of Simple Signal that remained unpaid as of closing, and escrow fund deposits. The acquisition was accounted for using the acquisition method of accounting under which assets and liabilities of Simple Signal were recorded at their respective fair values including an amount for goodwill representing the difference between the acquisition consideration and the fair value of the identifiable net assets. We do not expect any portion of this goodwill to be deductible for tax purposes. The goodwill attributable to the acquisition has been recorded as a non-current asset and is not amortized, but is subject to an annual review for impairment. The table below summarizes the Simple Signal assets acquired and liabilities assumed as of April 1, 2015: Acquisition Date Fair Value Assets Current assets: Cash and cash equivalents $ 53 Current assets 1,042 Total current assets 1,095 Property and equipment 979 Software 401 Intangible assets 6,407 Deferred tax assets, net, non-current 741 Total assets acquired 9,623 Liabilities Current liabilities: Accounts payable 785 Accrued expenses 593 Deferred revenue, current portion 370 Total current liabilities 1,748 Total liabilities assumed 1,748 Net identifiable assets acquired 7,875 Goodwill 17,703 Total purchase price $ 25,578 Pro forma financial information (unaudited) The following unaudited supplemental pro forma information presents the combined historical results of operations of Vonage and Nexmo for the years ended December 31, 2016 and 2015, as if the acquisition had been completed at January 1, 2015. For the years ended December 31, 2016 December 31, 2015 Revenue $ 989,846 $ 958,416 Net income attributable to Vonage 8,403 5,679 Net income attributable to Vonage per share - basic 0.04 0.03 Net income attributable to Vonage per share - diluted 0.04 0.02 The pro forma financial information includes certain adjustments to reflect expenses in the appropriate pro forma periods as though the companies were combined as of the beginning of 2015 and includes the pro-forma impact of amortization of identifiable intangibles assets and interest expense on borrowings under our revolving line of credit utilized to, in part, finance the acquisition. The pro forma data was also adjusted to eliminate non-recurring transaction costs incurred by us as well as the related tax impact. The pro forma results are not necessarily indicative of the results that we would have achieved had the transaction actually occurred on January 1, 2015 and does not purport to be indicative of future financial operating results nor does it reflect any operating efficiencies and cost savings that may be realized from the integration of the acquisition.

Property and Equipment (Notes)

Property and Equipment (Notes)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure	Property and Equipment December 31, 2017 December 31, 2016 Network equipment and computer hardware $ 79,990 $ 93,437 Building (under capital lease through August 31, 2017) — 25,709 Leasehold improvements 36,987 44,293 Customer premise equipment 12,884 9,700 Furniture 4,668 4,239 Vehicles 17 203 134,546 177,581 Less accumulated depreciation (87,792 ) (129,166 ) Property, plant and equipment 46,754 48,415

Accrued Liabilities (Notes)

Accrued Liabilities (Notes)	12 Months Ended
	Dec. 31, 2017
Accrued Liabilities [Abstract]
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	Accrued Liabilities December 31, 2017 December 31, 2016 Compensation and benefits, related taxes and temporary labor $ 30,059 $ 35,525 Marketing 10,759 12,754 Taxes and fees 13,353 19,234 Acquisition related consideration accounted for as compensation 2,534 6,608 Telecommunications 16,068 14,896 Settlement — 5,000 Other accruals 6,782 10,256 Customer credits 2,310 2,074 Professional fees 1,618 1,680 Inventory 1,927 1,168 $ 85,410 $ 109,195

Discontinued Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations On March 31, 2015, the Company completed its previously announced exit from the Brazilian market for consumer telephony services and the associated wind down of its joint venture operations in the country. The Company incurred a loss on disposal of $824 . The loss on disposal is comprised of the write-off of noncontrolling interest of $907 , foreign currency loss on intercompany loan forgiveness of $783 , and residual cumulative translation of $192 , partially offset by a tax benefit of $1,058 . The results of operations of this discontinued operation are as follows: For the year ended December 31, 2015 Revenues $ 33 Operating expenses 1,648 Loss from discontinued operations (1,615 ) Loss on disposal, net of taxes (824 ) Net loss from discontinued operations (2,439 ) Plus: Net loss from discontinued operations attributable to noncontrolling interest 59 Net loss from discontinued operations attributable to Vonage $ (2,380 )

Industry Segment and Geographic

Industry Segment and Geographic Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Industry Segment and Geographic Information	Industry Segment and Geographic Information ASC 280, Segment Reporting, establishes reporting standards for an enterprise's business segments and related disclosures about its products, services, geographic areas and major customers. Under ASC 280, the method for determining what information to report is based upon the way management organizes the operating segments within the Company for making operating decisions and assessing financial performance. Our chief operating decision-makers review revenue and gross margin information for each of our reportable segments, but do not review operating expenses on a segment by segment basis. In addition, with the exception of goodwill and intangible assets, we do not identify or allocate our assets by the reportable segments. Historically, we have had two operating segments that we have aggregated for reporting purposes. In 2016, as a result of the acquisition of Nexmo, we no longer meet the aggregation criteria for operating segments and now have the following two reportable segments: Business For our Business customers, we provide innovative, cloud-based Unified Communications as a Service, or UCaaS, solutions, comprised of integrated voice, text, video, data, collaboration, and mobile applications over our flexible, scalable SIP based Voice over Internet Protocol, or VoIP, network. Through Nexmo, the Vonage API Platform, we also offer Communications Platform as a Service, or CPaaS, solutions designed to enhance the way businesses communicate with their customers embedding communications into apps, websites and business processes. Together we have a robust set of product families tailored to serve the full range of the business value chain, from the small and medium business, or SMB, market, through mid-market and enterprise markets. We provide customers with multiple deployment options, designed to provide the reliability and quality of service they demand. We provide customers the ability to integrate our cloud communications platform with many cloud-based productivity and CRM solutions, including Google’s G Suite, Zendesk, Salesforce’s Sales Cloud, Oracle, Clio, and other CRM solutions. In combination, our products and services permit our business customers to communicate with their customers and employees through any cloud-connected device, in any place, at any time without the often costly investment required with on-site equipment. Consumer For our Consumer customers, we enable users to access and utilize our UCaaS services and features, via a single “identity,” either a number or user name, regardless of how they are connected to the Internet, including over 3G/4G, LTE, Cable, or DSL broadband networks. This technology enables us to offer our Consumer customers attractively priced voice and messaging services and other features around the world on a variety of devices. For our segments we categorize revenues as follows: Services revenues. Services revenues consists primarily of revenue attributable to our communication services for Consumer and UCaaS and CPaaS services for Business, Product revenues . Product revenues includes equipment sold to customers, shipping and handling, professional services, and broadband access. USF revenues. USF revenues represent fees passed on to customers to offset required contributions to the USF. For our segments we categorize cost of revenues as follows: Services cost of revenues. Services cost of revenues consists of costs associated with network operations and technical support personnel, communication origination, and termination services provided by third party carriers and excludes depreciation and amortization. Product cost of revenues . Product cost of revenues includes equipment sold to customers, shipping and handling, professional services, cost of certain products including equipment or services that we give customers as promotions, and broadband access. USF cost of revenues. USF cost of revenues represent contributions to the USF and related fees. Information about our segment results for the years ended December 31, 2017 , 2016 , and 2015 were as follows: Year ended December 31, 2017 Business Consumer Total Revenues Service revenues $ 419,591 $ 454,340 $ 873,931 Product revenues (1) 52,498 525 53,023 Service and product revenues 472,089 454,865 926,954 USF revenues 26,833 48,499 75,332 Total revenues 498,922 503,364 1,002,286 Cost of revenues Service cost of revenues (2) 190,934 80,454 271,388 Product cost of revenues (1) 51,026 7,208 58,234 Service and product cost of revenues 241,960 87,662 329,622 USF cost of revenues 26,833 48,499 75,332 Total cost of revenues 268,793 136,161 404,954 Segment gross margin Service margin 228,657 373,886 602,543 Product margin 1,472 (6,683 ) (5,211 ) Gross margin ex-USF (Service and product margin) 230,129 367,203 597,332 USF margin — — — Total segment gross margin $ 230,129 $ 367,203 $ 597,332 Segment gross margin % Service margin % 54.5 % 82.3 % 68.9 % Gross margin ex-USF (Service and product margin %) 48.7 % 80.7 % 64.4 % Segment gross margin % 46.1 % 72.9 % 59.6 % (1) Includes customer premise equipment, access, professional services, and shipping and handling. (2) Excludes depreciation and amortization of $20,100 , $7,208 , and $27,308 , respectively. Year ended December 31, 2016 Business Consumer Total Revenues Service revenues $ 301,877 $ 522,515 $ 824,392 Product revenues (1) 52,450 702 53,152 Service and product revenues 354,327 523,217 877,544 USF revenues 22,025 56,052 78,077 Total revenues 376,352 579,269 955,621 Cost of revenues Service cost of revenues (2) 111,485 100,054 211,539 Product cost of revenues (1) 51,129 14,394 65,523 Service and product cost of revenues 162,614 114,448 277,062 USF cost of revenues 22,036 56,052 78,088 Total cost of revenues 184,650 170,500 355,150 Segment gross margin Service margin 190,392 422,461 612,853 Product margin 1,321 (13,692 ) (12,371 ) Gross margin ex-USF (Service and product margin) 191,713 408,769 600,482 USF gross margin (11 ) — (11 ) Total segment gross margin $ 191,702 $ 408,769 $ 600,471 Segment gross margin % Service margin % 63.1 % 80.9 % 74.3 % Gross margin ex-USF (Service and product margin %) 54.1 % 78.1 % 68.4 % Segment gross margin % 50.9 % 70.6 % 62.8 % (1) Includes customer premise equipment, access, professional services, and shipping and handling. (2) Excludes depreciation and amortization of $18,820 , $9,669 , and $28,489 , respectively. Year ended December 31, 2015 Business Consumer Total Revenues Service revenues $ 170,489 $ 612,822 $ 783,311 Product revenues (1) 35,545 645 36,190 Service and product revenues 206,034 613,467 819,501 USF revenues 12,993 62,578 75,571 Total revenues 219,027 676,045 895,072 Cost of revenues Service cost of revenues (2) 44,997 123,580 168,577 Product cost of revenues (1) 31,185 20,616 51,801 Service and product cost of revenues 76,182 144,196 220,378 USF cost of revenues 13,022 62,578 75,600 Total cost of revenues 89,204 206,774 295,978 Segment gross margin Service margin 125,492 489,242 614,734 Product margin 4,360 (19,971 ) (15,611 ) Gross margin ex-USF (Service and product margin) 129,852 469,271 599,123 USF margin (29 ) — (29 ) Total segment gross margin $ 129,823 $ 469,271 $ 599,094 Segment gross margin % Service margin % 73.6 % 79.8 % 78.5 % Gross margin ex-USF (Service and product margin %) 63.0 % 76.5 % 73.1 % Segment gross margin % 59.3 % 69.4 % 66.9 % (1) Includes customer premise equipment, access, professional services, and shipping and handling. (2) Excludes depreciation and amortization of $15,819 , $9,049 , and $24,868 , respectively. A reconciliation of the total of the reportable segments' gross margin to consolidated income before provision for income taxes is as follows: Years Ended December 31, 2017 2016 2015 Total reportable gross margin $ 597,332 $ 600,471 $ 599,094 Sales and marketing 313,251 330,969 347,896 Engineering and development 29,630 29,759 27,220 General and administrative 122,537 123,304 109,153 Depreciation and amortization 72,523 72,285 61,833 Income from operations 59,391 44,154 52,992 Interest income 17 79 89 Interest expense (14,868 ) (13,042 ) (8,786 ) Other income (expense), net 1,253 (346 ) (842 ) Income before income taxes $ 45,793 $ 30,845 $ 43,453 Information about our operations by geographic location is as follows: For the years ended December 31, 2017 2016 2015 Revenues: United States $ 851,413 $ 872,147 $ 854,706 Canada 30,252 27,417 25,935 United Kingdom 28,309 17,365 14,431 Other Countries (1) 92,312 38,692 — $ 1,002,286 $ 955,621 $ 895,072 (1) No individual other international country represented greater than 9% of total revenue during the periods presented. December 31, 2017 December 31, 2016 Long-lived assets: United States $ 615,432 $ 629,269 United Kingdom 365 450 Israel 243 286 $ 616,040 $ 630,005

Cash Flow Information (Notes)

Cash Flow Information (Notes)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Cash Flow Information	Cash Flow Information Detail of supplemental disclosures for cash flow and non-cash investing and financing information was For the years ended December 31, (In thousands) 2017 2016 2015 Supplemental disclosures of cash flow information: Cash paid during the periods for: Interest $ 13,323 $ 11,621 $ 7,834 Income taxes 6,760 5,335 2,516 Non-cash investing and financing activities: Capital expenditures included in accounts payable and accrued liabilities $ 2,345 $ 3,610 $ 8,741 Issuance of common stock in connection with acquisition of business — 31,591 5,578 Purchase of intangible assets — — 5,000 Contingent consideration in connection with acquisition of business — 16,472 — Assumption of options in connection with acquisition of business — 4,779 —

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) Refer to Note 3, Correction of Prior Period Financial Statements for correction to the quarter ended December 31, 2016 and Note 12, Acquisition of Business for a description of the effect of unusual or infrequently occurring events during the quarterly periods. Summarized unaudited quarterly financial data is as follows: March 31, June 30, September 30, December 31, Year Ended 2017 Revenue 243,347 251,836 253,083 254,020 Income from operations 5,124 6,659 24,623 22,985 Net income attributable to Vonage 5,913 4,825 10,602 (55,273 ) Net income attributable to Vonage per common share: Basic net income per share Basic net income per share attributable to Vonage 0.03 0.02 0.05 (0.24 ) Diluted net income per share Diluted net income per share attributable to Vonage 0.02 0.02 0.04 (0.24 ) Year Ended 2016 (1) Revenue 226,824 233,675 248,359 246,763 Income from operations 18,524 5,387 15,029 5,214 Net income attributable to Vonage 7,931 218 7,040 (2,038 ) Net income attributable to Vonage per common share: Basic net income per share Basic net income per share attributable to Vonage 0.04 — 0.03 (0.01 ) Diluted net income per share Diluted net income per share attributable to Vonage 0.04 — 0.03 (0.01 ) (1) see Note 3. Correction of Prior Period Financial Statements

Summary of Significant Accoun28

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Principles of Consolidation	Principles of Consolidation The consolidated financial statements have been prepared in accordance with U.S. GAAP. The Accounting Standards Codification, ASC, established by the Financial Accounting Standards Board, FASB, is the source of authoritative GAAP to be applied to nongovernmental entities. In addition, the rules and interpretive releases of the Securities and Exchange Commission, SEC, under the authority of federal securities laws are also sources of authoritative GAAP for SEC registrants. The consolidated financial statements include the accounts and operations of Vonage and its wholly-owned subsidiaries for which we have a controlling interest. All intercompany balances and transactions have been eliminated in consolidation. The usual condition for a controlling financial interest is ownership of a majority of the voting interests of an entity; however, a controlling financial interest may also exist through arrangements that do not involve controlling voting interests. As such, Vonage applies the guidance of ASC 810, Consolidations , or ASC 810, to determine when an entity that is insufficiently capitalized or not controlled through its voting interests, referred to as a VIE, should be consolidated. In addition, the results of companies acquired or disposed of are included in the consolidated financial statements from the effective date of the acquisition or up to the date of disposal.
Revenue Recognition	Revenue Recognition Operating revenues consist of services revenues and customer equipment (which enables our services) and shipping revenues. The point in time at which revenues are recognized is determined in accordance with SEC Staff Accounting Bulletin, SAB, No. 104, Revenue Recognition, and ASC 605, Revenue Recognition . At the time a customer signs up for our services, there are the following deliverables: • Providing equipment, if any, to the customer that enables our telephony services; • Providing services; and • Installation of equipment if required in the contract or terms of service. Activation devices are provided free of charge to our Consumer customers while VOIP enabled phones are provided for a fee to our Business customers. In most instances there are no fees collected at sign-up. We record the fees collected for shipping the equipment to the customer, if any, as shipping and handling revenue at the time of shipment. Services Revenue Substantially all of our revenues are services revenues, which are derived , usage based billion, and, in Vonage Enterprise, we offer domestic and international rate plans, including a variety of residential plans and mobile plans. For consumer customers in the United States, we offer domestic and international rate plans, including a variety of residential plans and mobile plans. For business customers, we offer SMB, mid-market, and enterprise customers several service plans with different pricing structures and contractual requirements ranging in duration from month-to-month to three years. In addition, we provide managed equipment to business customers for which the customers pay a monthly fee. Customers also have the opportunity to purchase premium features for additional fees. We also derive services revenues from per minute fees for international calls if not covered under a plan, including calls made via applications for mobile devices and other stand-alone products, and for any calling minutes in excess of a customer’s monthly plan limits. For a portion of our customers, monthly subscription fees are automatically charged to customers’ credit cards, debit cards or electronic check payments, or ECP, in advance and are recognized over the following month when services are provided. Revenues generated from international calls and from customers exceeding allocated call minutes under limited minute plans are recognized as services are provided, that is, as minutes are used, and are billed to a customer's credit cards, debit cards or ECP in arrears. As a result of multiple billing cycles each month, we estimate the amount of revenues earned from international calls and from customers exceeding allocated call minutes under limited minute plans but not billed from the end of each billing cycle to the end of each reporting period and record these amounts as accounts receivable. These estimates are based primarily upon historical minutes and have been consistent with our actual results. In the United States, we charge regulatory, compliance, E-911, and intellectual property-related fees on a monthly basis to defray costs, and to cover taxes that we are charged by the suppliers of telecommunications services. These charges, along with the remittance to the relevant government entity, are recorded on a net basis. In addition, we collect Federal Universal Service Fund, or USF, fees from customers to recover our obligation to contribute to the fund, as allowed by the FCC. We recognize USF revenues on a gross basis and record the related fees in cost of services. Services revenue also includes supplying messaging (SMS and Voice) services to customers as part of our CPaaS business. Revenue is recognized in the period when messages are sent by the customer. We also transact with providers or bulk SMS aggregators and sell services to these customers who then onsell to their customers. Since the aggregator is our customer, revenue is recognized on a gross basis with related costs included in cost of sales. Customer Equipment and Shipping Revenue Revenue is generated from sales of customer equipment to wholesalers or directly to customers for replacement devices, or for upgrading their device at the time of customer sign-up for which we charge an additional fee. In addition, customer equipment and shipping revenues include revenues from the sale of VoIP telephones in order to access our small and medium business services. Customer equipment and shipping revenues also include the fees that customers are charged for shipping their customer equipment to them. Customer equipment and shipping revenues include sales to our wholesalers, who subsequently resell this customer equipment to customers. Revenues are reduced for payments to wholesalers and rebates to customers to the extent of customer equipment and shipping revenues.
Cost of Services/Goods Sold	Cost of Services Cost of service consists of costs that we pay to third parties such as access and interconnection charges that we pay to other companies to terminate domestic and international phone calls on the public switched telephone network. In addition, costs to lease phone numbers, to co-locate in other companies’ facilities, to provide enhanced emergency dialing capabilities to transmit 911 calls, and to provide local number portability are also included in cost of service. These costs also include taxes that we pay on telecommunications services from our suppliers or are imposed by government agencies such as USF contributions and royalties for use of third parties’ intellectual property. In addition, these costs include certain personnel and related costs for network operations and technical support that are attributable to revenue generating activities. Cost of services excludes depreciation and amortization expense of $27,308 , $28,489 , and $24,868 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Cost of Goods Sold Cost of goods sold consists primarily of costs incurred on customer equipment for customers who subscribe through the direct sales channel in excess of activation fees. The amortization of deferred customer equipment, the cost of shipping and handling for customer equipment, and the cost of certain promotions are also included in cost of goods sold.
Sales and Marketing Expenses	Sales and Marketing Expenses Sales and marketing expenses consist primarily of personnel and related costs for employees and contractors directly associated with our sales and marketing activities, internet advertising fees, radio and billboard advertising, public relations, commissions paid to employees, resellers and other third parties, trade shows, marketing and promotional activities, customer support, credit card fees, collections, and systems and information technology support. We expense advertising costs during the period in which they are incurred. Advertising costs included in sales and marketing were $57,703 , $75,587 , and $103,320 for the years ended December 31, 2017 , 2016 , and 2015 , respectively.
Engineering and Development Expenses	Engineering and Development Expenses Engineering and development expenses primarily include personnel and related costs for developers responsible for new products, and software engineers maintaining and enhancing existing products. Research and development costs related to new product development included in engineering and development were $23,730 , $22,447 , and $18,350 for the years ended December 31, 2017 , 2016 , and 2015 , respectively. Costs for research, including predevelopment efforts prior to establishing technological feasibility of software expected to be marketed, are expensed as incurred. Development costs are capitalized when technological feasibility has been established and anticipated future revenues support the recoverability of the capitalized amounts. Capitalization stops when the product is available for general release to customers. Due to the short time period between achieving technological feasibility and product release and the insignificant amount of costs incurred during such periods, we have not capitalized any software development, and have expensed these costs as incurred.
Restructuring Activities	Restructuring Activities For the year ended December 31, 2017 , we recognized $5,101 of costs associated with restructuring activities included in general and administrative expense. This amount is primarily comprised of costs associated with severance and other employee related costs. As of December 31, 2017, $1,090 remained accrued related to restructuring activities and $4,011 was paid during 2017.
Cash, Cash Equivalents and Marketable Securities	Cash, Cash Equivalents and Marketable Securities We maintain cash with several investment grade financial institutions. Highly liquid investments, which are readily convertible into cash, with original maturities of three months or less, are recorded as cash equivalents. Management determines the appropriate classification of our investments in debt and marketable equity securities at the time of purchase and reevaluates such designation at each balance sheet date. Our debt securities have been classified and accounted for as available for sale. In response to changes in the availability of and the yield on alternative investments as well as liquidity requirements, we may sell these securities prior to their stated maturities. These securities are carried at fair value, with the unrealized gains and losses reported as a component of other comprehensive income (loss). Any realized gains or losses on the sale of marketable securities are determined on a specific identification method, and such gains and losses are reflected as a component of other income or expense.
Certain Risks and Concentrations	Certain Risks and Concentrations Financial instruments that potentially subject us to concentrations of credit risk consist principally of cash equivalents, marketable securities, and accounts receivable. They are subject to fluctuations in both market value and yield based upon changes in market conditions, including interest rates, liquidity, general economic conditions, and conditions specific to the issuers. Accounts receivable are typically unsecured and are derived from revenues earned from customers primarily located in the United States. A portion of our accounts receivable represents the timing difference between when a customer’s credit card is billed and the subsequent settlement of that transaction with our credit card processors. This timing difference is generally three days for substantially all of our credit card receivables. We have never experienced any accounts receivable write-offs due to this timing difference. In addition, we collect subscription fees in advance, minimizing our accounts receivable and bad debt exposure. If a customer’s credit card, debit card or ECP is declined, we generally suspend international calling capabilities as well as their ability to incur domestic usage charges in excess of their plan minutes. Generally, if the customer’s credit card, debit card or ECP could not be successfully processed during three
Inventory	Inventory Inventory consists of the cost of customer equipment and is valued at the lower of cost or market, with cost determined using the average cost method. We provide an inventory allowance for customer equipment that has been returned by customers but may not be able to be reissued to new customers or returned to the manufacturer for credit.
Property and Equipment	Property and Equipment Property and equipment includes acquired assets and those accounted for under capital leases and consist principally of network equipment and computer hardware, software, furniture, and leasehold improvements. Company-owned equipment in use at customer premises is also included in property and equipment. Network equipment, computer hardware and furniture are stated at cost with depreciation provided using the straight-line method over the estimated useful lives of the related assets, which range from three to five years. Leasehold improvements are amortized over their estimated useful life of the related assets or the life of the lease, whichever is shorter. The cost of substantial improvements is capitalized while the cost of maintenance and repairs is charged to operating expenses as incurred. Company-owned customer premises equipment is depreciated on a straight-line basis over three years. Our network equipment and computer hardware, which consists of routers, gateways, and servers that enable our services, is subject to technological risks and rapid market changes due to new products and services and changing customer demand. These changes may result in future adjustments to the estimated useful lives or the carrying value of these assets, or both.
Software Costs	Software Costs We capitalize certain costs, such as purchased software and internally developed software that we use for customer acquisition and customer care automation tools, in accordance with FASB ASC 350-40, Internal-Use Software . Computer software is stated at cost less accumulated amortization and the estimated useful life is two to five years.
Goodwill	Goodwill In accordance with ASC 350, Intangibles - Goodwill and Other , we recognize goodwill for the excess cost of an acquired business over the fair value assigned to assets acquired and liabilities assumed. Goodwill is tested for impairment on an annual basis on October 1st and, when specific circumstances dictate, between annual tests. When impaired, the carrying value of goodwill is written down to fair value. The goodwill impairment test involves evaluating qualitative information to determine if it is more than 50% likely that the fair value of a reporting unit is less than its carrying value. If such a determination is made or if an entity chooses not to perform a qualitative assessment, then the traditional two-step goodwill impairment test described below must be applied. The first step, identifying a potential impairment, compares the fair value of a reporting unit with its carrying amount, including goodwill. If the carrying value of the reporting unit exceeds its fair value, the second step would need to be conducted; otherwise, no further steps are necessary as no potential impairment exists. The second step, measuring the impairment loss, compares the implied fair value of the reporting unit goodwill with the carrying amount of that goodwill. Any excess of the reporting unit goodwill carrying value over the respective implied fair value is recognized as an impairment loss. There was no impairment of goodwill for the years ended December 31, 2017 , 2016 , and 2015 .
Intangible Assets, Patents and Pantent Licenses	Intangible Assets Intangible assets acquired in the settlement of litigation or by direct purchase are accounted for based upon the fair value of assets received. Purchased-intangible assets are accounted for based upon the fair value of assets received and are amortized on a straight-line or accelerated basis over the periods of economic benefit, ranging from two to ten years. We perform a review of purchased-intangible assets whenever events or changes in circumstances indicate that the useful life is shorter than we had originally estimated or that the carrying amount of assets may not be recoverable. If such facts and circumstances exist, we assess the recoverability of purchased-intangible assets by comparing the projected undiscounted net cash flows associated with the related asset or group of assets over their remaining lives against their respective carrying amounts. Impairments, if any, are based on the excess of the carrying amount over the fair value of those assets. If the useful life of the asset is shorter than originally estimated, we accelerate the rate of amortization and amortize the remaining carrying value over the new shorter useful life. There was no impairment of purchased-intangible assets identified for the years ended December 31, 2017 , 2016 , and 2015 . Patents and Patent Licenses Patent rights acquired in the settlement of litigation or by direct purchase are accounted for based upon the fair value of assets received.
Asset Impairments	Asset Impairments We evaluate impairment losses on long-lived assets used in operations when events and changes in circumstances indicate that the assets might be impaired. If our review indicates that the carrying value of an asset will not be recoverable, based on a comparison of the carrying value of the asset to the undiscounted future cash flows, the impairment will be measured by comparing the carrying value of the asset to its fair value. Fair value will be determined based on quoted market values, discounted cash flows or appraisals. Impairments of property and equipment are recorded in the statement of income as part of depreciation expense. There was no impairment of property and equipment identified for the years ended December 31, 2017 , 2016 , and 2015 .
Debt Related Costs	Debt Related Costs Costs incurred in raising debt are deferred and amortized as interest expense using the effective interest method over the life of the debt. Costs associated with term loans are netted against the underlying notes payable in accordance with ASU 2015-15, "Interest-Imputation of Interest" while costs deferred associated with revolving facilities are included in other assets.
Restricted Cash and Letter of Credit	Restricted Cash and Letters of Credit We had a cash collateralized letter of credit for $1,563 and $1,578 as of December 31, 2017 and 2016 , respectively, mainly related to lease deposits for our Holmdel office. In the aggregate, cash reserves and collateralized letters of credit of $1,967 and $1,851 were recorded as long-term restricted cash at December 31, 2017 and 2016 , respectively.
Derivative Financial Instruments	Derivative Financial Instruments The Company accounts for derivative financial instruments under ASC 815, Derivatives and Hedging, which requires the Company to record all derivatives on the balance sheet at fair value unless they qualify for a normal purchase normal sale exception. Changes in the fair value of non-hedge derivatives are immediately recognized into earnings. Changes in the fair value of derivatives accounted for as hedges, if elected for hedge accounting, are either recognized in earnings as an offset to the changes in the fair value of the related hedged assets and liabilities or deferred and recognized as a component of accumulated other comprehensive income, or OCI, until the hedged transactions occur and are recognized in earnings. During 2017, the Company entered into an interest rate swap to mitigate variability in earnings due to fluctuations in interest rates and has been designated and qualifies as a cash flow hedge. The Company assesses hedge effectiveness under the critical terms matched method at inception and at least quarterly through the life of the hedging relationship. If the critical terms of the interest rate swap match the terms of the forecasted transaction, the Company concludes that the hedge is effective.
Income Taxes	Income Taxes We recognize deferred tax assets and liabilities at enacted income tax rates for the temporary differences between the financial reporting bases and the tax bases of our assets and liabilities. Any effects of changes in income tax rates or tax laws are included in the provision for income taxes in the period of enactment. Our net deferred tax assets primarily consist of net operating loss carry forwards, or NOLs. We are required to record a valuation allowance against our net deferred tax assets if we conclude that it is more likely than not that taxable income generated in the future will be insufficient to utilize the future income tax benefit from our net deferred tax assets prior to expiration. We periodically review this conclusion, which requires significant management judgment. If we are able to conclude in a future period that a future income tax benefit from our net deferred tax assets has a greater than 50% likelihood of being realized, we are required in that period to reduce the related valuation allowance with a corresponding decrease in income tax expense. This would result in a non-cash benefit to our net income in the period of the determination. In the future, if available evidence changes our conclusion that it is more likely than not that we will utilize our net deferred tax assets prior to their expiration, we will make an adjustment to the related valuation allowance and income tax expense at that time. In subsequent periods, we would expect to recognize income tax expense equal to our pre-tax income multiplied by our effective income tax rate, an expense that was not recognized prior to the reduction of the valuation allowance. Our effective rate may differ from the federal statutory rate due, in part, to our foreign operations and certain discrete period items. On December 22, 2017, the Tax Cuts and Jobs Act, or TCJA, was signed into law by the President of the United States. The TCJA most notably reduces the corporate tax rate from 35% to 21% along with eliminating the alternative minimum tax, or AMT, and imposing a mandatory one-time tax on foreign earnings. Under ASC 740, Income Taxes , an entity is required to recognize the effect of tax law changes during the period of enactment. As such, the Company will be reflecting the impact of this law within its December 31, 2017 financial statements. Due to the complexities of the new legislation and associated accounting considerations, SEC SAB 118 provides for an entity to utilize a provisional estimate within its financial statements for the impact of the TCJA. Based upon currently available information, the Company estimates that the enactment of the legislation will result in a charge to income tax expense of $69,378 which is primarily associated with the re-measurement of the Company’s deferred tax balances at the 21% income tax rate. The Company also reclassified the deferred tax asset related to AMT credits to receivables which are now refundable in the amount of $8,217 , of which $4,108 is included in other current assets as of December 31, 2017. The Company does not currently estimate a material impact associated with the repatriation tax or other facets of the TCJA. Due to the timing of the enactment and the complexity involved in applying the provisions of the TCJA, the Company has made reasonable estimates of the effects and recorded provisional amounts in our financial statements as of December 31, 2017. Additionally, the Company is currently analyzing our global working capital and cash requirements and the potential tax liabilities attributable to a repatriation but we have yet to determine whether we plan to change our prior assessment and repatriate earnings. As such, we have not recorded any deferred taxes attributable to our investments in our foreign entities and will record the tax effects of any change in our prior assertion as we complete our analysis of the TCJA. As we collect further information and interpret the TCJA and any additional guidance issued by the U.S. Treasury Department, the IRS and other regulatory bodies, we may make adjustments to the provisional amounts. The Company will continue to analyze the effects of the TCJA on the Company’s operations and will record any adjustments associated with the enactment of the legislature during the measurement period as provided by SAB 118. The accounting for the impact of the TCJA will be completed in 2018. We file income tax returns in the U.S. for federal and state purposes and in various foreign jurisdictions. Our federal tax return remains subject to examination by the Internal Revenue Service from 2014 to present, our New Jersey tax returns remain open from 2013 to present, our Canada tax return remains open from 2014 to present, and other domestic and foreign tax returns remain open for all periods to which those filings relate. Our Canadian corporate income tax returns for 2012 and 2013 were selected for examination by the Canada Revenue Agency. The Canada Revenue Agency concluded their audit and there were no changes. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50% likelihood of being realized upon ultimate resolution.
Business Combinations	Business Combinations We account for business combinations using the acquisition method of accounting. The acquisition method of accounting requires that the purchase price, including the fair value of contingent consideration, of the acquisition be allocated to the assets acquired and liabilities assumed using the fair values determined by management as of the acquisition date. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of assets acquired and the liabilities assumed. While the Company uses its best estimates and assumptions as part of the purchase price allocation process to accurately value assets acquired and liabilities assumed at the acquisition date, the Company’s estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, the Company records adjustments to the assets acquired and liabilities assumed, with the corresponding offset to goodwill to the extent the Company identifies adjustments to the preliminary purchase price allocation. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to the consolidated statements of operations. We include the results of all acquisitions in our consolidated financial statements from the date of acquisition. Acquisition related transaction costs, such as banking, legal, accounting and other costs incurred in connection with an acquisition, are expensed as incurred in general and administrative expense. Acquisition related integration costs include costs associated with exit or disposal activities, which do not meet the criteria of discontinued operations, including costs for employee, lease, and contract terminations, facility closing or other exit activities. Additionally, these costs include expenses directly related to integrating and reorganizing acquired businesses and include items such as employee retention costs, recruiting costs, certain moving costs, certain duplicative costs during integration and asset impairments. These costs are expensed as incurred in general and administrative expense. Acquisition related consideration accounted for as compensation expense, such as restricted cash, restricted stock and option related costs incurred in connection with an acquisition are included in general and administrative expense.
Foreign Currency	Foreign Currency Generally, the functional currency of our non-United States subsidiaries is the local currency. However, the functional currency of Nexmo's United States's subsidiary is the Euro. The financial statements of these subsidiaries are translated to their respective functional currency using month-end rates of exchange for assets and liabilities, and average rates of exchange for revenues, costs, and expenses. Translation gains and losses from the Company's net investments in subsidiaries are deferred and recorded in accumulated other comprehensive income as a component of stockholders’ equity until sale or complete or substantially complete liquidation of the net investment in the foreign entity takes place. Foreign currency transaction gains or losses are reported within other income/(expense) in the Company's consolidated statements of operations. For the years ended December 31, 2017, 2016 and 2015, amounts recognized as foreign currency transaction losses were $620 , $346 and $860 , respectively.
Share-Based Compensation	Share-Based Compensation We account for share-based compensation in accordance with FASB ASC 718, “Compensation-Stock Compensation”. Under the fair value recognition provisions of this pronouncement, share-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the applicable vesting period of the stock award on a straight-line basis.
Comprehensive Income	Comprehensive Income Comprehensive income consists of net income (loss) and other comprehensive items. Other comprehensive items include changes in the fair value of derivatives, foreign currency translation adjustments and unrealized gains (losses) on available for sale securities.
Use of Estimates	Use of Estimates Our consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States, which require management to make estimates and assumptions that affect the amounts of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. We base our estimates on historical experience, available market information, appropriate valuation methodologies, and on various other assumptions that we believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Estimates are used for such items as depreciable lives for long-lived assets including intangible assets, tax provisions, uncollectible accounts, and assets and liabilities assumed in business combinations, among others. In addition, estimates are used to test long-lived assets and goodwill for impairment.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2017, FASB issued ASU 2017-12, "Derivatives and Hedging". The ASU improves the financial reporting of hedging relationships to better portray the economic results of an entity's risk management activities in its financial statements and simplifies the application of the hedge accounting guidance in current GAAP. It also amends the disclosures requirements by requiring a tabular disclosure related to the effect on the incomes statement of fair value and cash flow hedges and eliminating the ineffective portion of the change in fair value of hedging instrument disclosures. This ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted in any interim period after issuance of this ASU. We have evaluated the impact of adopting ASU 2017-12 on our consolidated financial statements and related disclosures and have determined that it will not have a material impact on our consolidated financial statements. In January 2017, FASB issued ASU 2017-04, "Intangibles - Goodwill and Other" which simplifies the subsequent measurement of goodwill and eliminates Step 2 from the goodwill impairment test. This ASU is effective for an annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019 on a prospective basis. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of ASU 2017-04 will not have a material impact on our consolidated financial statements. In August 2016, FASB issued ASU 2016-15, "Statement of Cash Flows". This ASU addresses eight specific cash flow issues with the objective of reducing the existing diversity in practice. This ASU is effective for fiscal years beginning after December 15, 2017 on a retrospective basis. Early adoption is permitted, including adoption in an interim period. The adoption of ASU 2016-15 will not have a material impact on our consolidated financial statements and related disclosures. In February 2016, FASB issued ASU 2016-02, "Leases". This ASU increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted for all entities. The adoption of this ASU will increase assets and liabilities for operating leases. We will adopt these ASUs when effective. We are currently evaluating the impact of adopting ASU 2016-02 on our consolidated financial statements and related disclosures. In May 2014, FASB issued ASU 2014-09, "Revenue from Contracts with Customers (Topic 606)" which was further amended through various updates issued by the FASB thereafter. The amendments of Topic 606 clarify the principles for recognizing revenue and provide a common revenue standard for U.S. GAAP and International Financial Reporting Standards, or IFRS, and to improve financial reporting. The core principle of these standards are that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Topic 606 also amends the current guidance for the recognition of costs to obtain and fulfill contracts with customers requiring that all incremental costs of obtaining and direct costs of fulfilling contracts with customers such as commissions be deferred and recognized over the expected customer life. In August 2015, an ASU was issued by the FASB which deferred the effective date to annual and interim periods beginning on or after December 15, 2017. As of January 1, 2018, we have adopted the requirements of the new standard using the modified retrospective transition method under which the standard will be applied only to the most current period presented and the cumulative effect of applying the standard will be recognized at the date of initial application as a cumulative adjustment to retained earnings. We have finalized our evaluation the impact of the standard with respect to the terms of our revenue arrangements and the Company expects the impact of the adoption of Topic 606 to be the capitalization of incremental costs to obtain a contract of approximately $35 million to $40 million with a corresponding offset being recorded to stockholder's equity. This asset will be amortized to expense over a period of five to seven years, subject to periodic reviews for impairment and life. The following standards were adopted by the Company during the current year: In November 2016, FASB issued ASU 2016-18, "Statement of Cash Flows". This ASU requires that a statement of cash flows explains the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. As a result, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. We adopted this ASU in the first quarter of 2017 and applied the retrospective transition method for each period presented. Upon adoption of ASU 2016-18, $716 and $20 were reclassified from investing activities and effect of exchange rate changes on cash, respectively, for the year ended December 31, 2016 and $813 and $5 were reclassified from investing activities and effect of exchange rate changes on cash, respectively, for the year ended December 31 2015. The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the consolidated balance sheet to same such amounts show in the consolidated statement of cash flows: As of December 31, 2017 2016 2015 2014 Cash and cash equivalents $ 31,360 $ 29,078 $ 57,726 $ 40,797 Restricted cash 1,967 1,851 2,587 3,405 $ 33,327 $ 30,929 $ 60,313 $ 44,202 In March 2016, FASB issued ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting". This ASU is issued as part of its Simplification Initiative. The areas for simplification in this ASU involve several aspects of the accounting for share- based payment transactions, including the income tax consequences, recognition of share-based expense, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This ASU is effective for fiscal years beginning after December 15, 2016, including interim periods within those fiscal years. Early adoption is permitted for any entity in any interim or annual period. We adopted this ASU in the first quarter of 2017. We elected to account for forfeitures when they occur versus our prior practice of estimating the number of awards that are expected to vest. The election of this new ASU resulted in a one-time adjustment in 2017 to accumulated deficit and to additional paid-in-capital of $5,668 and the corresponding benefit to our accumulated deficit and deferred tax asset of $2,285 related to the reversal of forfeiture rate as of January 1, 2017. In addition, a benefit to our accumulated deficit and deferred tax asset of $6,624 was recorded for excess tax benefits on equity compensation as of December 31, 2016. We also classified cash paid by us when directly withholding shares for tax-withholding purposes as a financing activity. As a result, $6,444 and $4,754 was reclassified from operating activity to financing activity for the years ended December 31, 2016 and 2015, respectively. In July 2015, FASB issued ASU 2015-11, "Simplifying the Measurement of Inventory". This ASU applies to inventory that is measured using first-in, first-out, or FIFO, or average cost. Under the updated guidance, an entity should measure inventory that is within scope at the lower of cost and net realizable value, which is the estimated selling prices in the ordinary course of business, less reasonably predicable costs of completion, disposal and transportation. Subsequent measurement is unchanged for inventory that is measured using last-in, first-out, or LIFO, or the retail inventory. This ASU is effective for annual and interim periods beginning after December 15, 2016, and should be applied prospectively with early adoption on permitted at the beginning of an interim and annual reporting period. We adopted ASU 2015-11 in the first quarter of 2017 and the adoption of this ASU did not have a material impact on our consolidated financial statements and related disclosures.
Accounts Receivable	three billing cycles, we terminate the account. In addition, we automatically charge any per minute fees to our customers’ credit card, debit card or ECP monthly in arrears. To further mitigate our bad debt exposure, a customer’s credit card, debit card or ECP will be charged in advance of their monthly billing if their international calling or overage charges exceed a certain dollar threshold.

Commitments and Contingencies C

Commitments and Contingencies Capital Lease (Policies)	12 Months Ended
	Dec. 31, 2017
- Cash, Cash Equivalents and Restricted Cash [Abstract]
Lessee, Leases [Policy Text Block]	Capital Leases Assets financed under capital lease agreements are included in property and equipment in the consolidated balance sheet and related depreciation and amortization expense is included in the consolidated statements of operations.

Summary of Significant Accoun30

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents [Table Text Block]	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the consolidated balance sheet to same such amounts show in the consolidated statement of cash flows: As of December 31, 2017 2016 2015 2014 Cash and cash equivalents $ 31,360 $ 29,078 $ 57,726 $ 40,797 Restricted cash 1,967 1,851 2,587 3,405 $ 33,327 $ 30,929 $ 60,313 $ 44,202

Correction of Prior Period Fi31

Correction of Prior Period Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Schedule of Error Corrections and Prior Period Adjustments	The impact to the consolidated balance sheet as of December 31, 2016 and the consolidated statements of income for the three months and year ended December 31, 2016 is as follows: Consolidated Balance Sheets As of December 31, 2016 As Reported Adjustment As Revised Deferred tax assets, non-current $ 188,966 $ 4,756 $ 184,210 Total assets 940,422 4,756 935,666 Accumulated deficit (637,113 ) 4,756 (641,869 ) Total stockholders' equity 441,297 4,756 436,541 Total liabilities and stockholders' equity 940,422 4,756 935,666 Consolidated Statements of Operations Three Months Ended December 31, 2016 Year Ended December 31, 2016 (Unaudited) As Reported Adjustment As Revised As Reported Adjustment As Revised Income tax expense $ (1,553 ) $ 2,039 $ (3,592 ) $ (12,938 ) $ 4,756 $ (17,694 ) Net income 1 2,039 (2,038 ) 17,907 4,756 13,151 Net income per common share: Basic $ — $ 0.01 $ (0.01 ) $ 0.08 $ 0.02 $ 0.06 Diluted $ — $ 0.01 $ (0.01 ) $ 0.08 $ 0.02 $ 0.06

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Computation for basic and diluted net (loss) income per share	The following table sets forth the computation for basic and diluted net income per share: For the years ended December 31, 2017 2016 2015 (Revised) (1) Numerator (Loss)/income from continuing operations $ (33,933 ) $ 13,151 $ 25,035 Discontinued operations — — (2,439 ) Plus: Net loss from discontinued operations attributable to noncontrolling interest — — 59 Loss from discontinued operations attributable to Vonage — — (2,380 ) Net (loss)/income attributable to Vonage $ (33,933 ) $ 13,151 $ 22,655 Denominator Basic weighted average common shares outstanding 225,311 215,751 213,147 Dilutive effect of stock options and restricted stock units — 16,190 10,963 Diluted weighted average common shares outstanding 225,311 231,941 224,110 Basic net (loss)/income per share Basic net (loss)/income per share - from continuing operations $ (0.15 ) $ 0.06 $ 0.12 Basic net loss per share - from discontinued operations attributable to Vonage — — (0.01 ) Basic net (loss)/income per share - attributable to Vonage $ (0.15 ) $ 0.06 $ 0.11 Diluted net income per share Diluted net (loss)/income per share - from continuing operations $ (0.15 ) $ 0.06 $ 0.11 Diluted net loss per share - from discontinued operations attributable to Vonage — — (0.01 ) Diluted net (loss)/income per share - attributable to Vonage $ (0.15 ) $ 0.06 $ 0.10 (1) see Note 3. Correction of Prior Period Financial Statements
Securities excluded from calculation of diluted earnings per common share because of anti-dilutive effects	The following shares were excluded from the calculation of diluted income per share because of their anti-dilutive effects: For the years ended December 31, 2017 2016 2015 Restricted stock units 11,928 8,282 5,827 Employee stock options 10,448 9,030 13,600 22,376 17,312 19,427

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table provides a summary of the changes in the carrying amounts of goodwill: Balance at January 1, 2016 $ 222,106 Increase in goodwill related to finalization of acquisition accounting for Simple Signal 16 Increase in goodwill related to finalization of acquisition accounting for iCore and immaterial correction of an error discussed further below 2,314 Goodwill recognized for the acquisition of Nexmo on June 3, 2016 143,073 Currency translation adjustments (7,146 ) Balance at December 31, 2016 360,363 Decrease in goodwill related to finalization of acquisition accounting for Nexmo (5,482 ) Currency translation adjustments 18,883 Balance at December 31, 2017 $ 373,764
Intangible assets, net	December 31, 2017 December 31, 2016 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value Customer relationships 7 to 12 years $ 184,465 $ (62,072 ) $ 122,393 $ 173,187 $ (39,413 ) $ 133,774 Developed technology 3 to 10 years 90,417 (44,413 ) 46,004 88,609 (31,364 ) 57,245 Patents and patent licenses 3 to 5 years 20,214 (16,184 ) 4,030 20,214 (14,667 ) 5,547 Trade names 2 to 5 years 1,708 (1,356 ) 352 1,820 (787 ) 1,033 Non-compete agreements 3 years 1,039 (548 ) 491 3,845 (2,188 ) 1,657 Total finite-lived intangible assets 297,843 (124,573 ) 173,270 287,675 (88,419 ) 199,256
Total expected future annual amortization	The total expected future annual amortization for the succeeding five years ended December 31 is as follows: Estimated Amortization Expense 2018 $ 35,747 2019 32,384 2020 27,934 2021 21,985 2022 17,006

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Components of income before income tax expense	The components of income from continuing operations before income tax expense are as follows: For the years ended December 31, 2017 2016 2015 United States $ 39,370 $ 31,076 $ 38,115 Foreign 6,423 (231 ) 5,338 $ 45,793 $ 30,845 $ 43,453
Components of income tax expense	The income tax provision from continuing operations consisted of the following amounts: For the years ended December 31, 2017 2016 2015 Current: Federal $ (1,101 ) $ (621 ) $ (1,846 ) Foreign (1,731 ) (1,064 ) (1,667 ) State and local taxes (2,317 ) (3,951 ) (956 ) $ (5,149 ) $ (5,636 ) $ (4,469 ) Deferred: Federal $ (75,928 ) $ (12,550 ) $ (11,289 ) Foreign 1,631 2 (1,088 ) State and local taxes (280 ) 490 (1,572 ) (74,577 ) (12,058 ) (13,949 ) $ (79,726 ) $ (17,694 ) $ (18,418 )
Reconciliation of income tax rate	The reconciliation between the United States federal statutory rate of 35% to the Company's effective rate is as follows: For the years ended December 31, 2017 2016 2015 U.S. Federal statutory tax rate 35 % 35 % 35 % Permanent items 10 % 10 % 3 % Effect of the Tax Cuts and Jobs Act 152 % — % — % Equity-based compensation (24 )% — % — % State and local taxes, net of federal benefit 5 % 7 % 2 % International tax (reflects effect of losses for which tax benefit not realized) (4 )% — % 1 % Valuation reserve for income taxes and other — % 5 % 2 % Effective tax rate 174 % 57 % 43 %
Components of deferred tax assets and liabilities	The temporary differences which gave rise to the Company's deferred tax assets consisted of the following: December 31, 2017 December 31, 2016 Assets and liabilities: Accounts receivable and inventory allowances $ 553 $ 816 Deferred rent 862 630 Contingent consideration — 1,482 Acquired intangible assets and property and equipment (39,077 ) (61,486 ) Accrued expenses 5,182 10,145 Research and development and alternative minimum tax credit 958 8,039 Stock option compensation 17,734 24,026 Capital leases 37 (7,762 ) Cumulative translation adjustments (714 ) — Deferred revenue 6,994 11,362 Derivatives (319 ) — Net operating loss carryforwards 141,072 215,504 133,282 202,756 Valuation allowance (22,390 ) (18,546 ) Deferred tax assets, net, non-current $ 110,892 $ 184,210
Schedule of Unrecognized Tax Benefits Roll Forward	The following table reconciles the total amounts of uncertain tax benefits: As of December 31, 2017 2016 Balance as of January 1 $ — — Increase due to current year positions 1,086 — Uncertain tax benefits as of December 31 $ 1,086 $ —

Long-Term Debt and Revolving 35

Long-Term Debt and Revolving Credit Facility (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Schedule of long-term debt	A schedule of long-term debt at December 31, 2017 and 2016 is as follows: December 31, 2017 December 31, 2016 2.50-3.25% Term note - due 2020, net of debt related costs 72,765 91,124 2.50-3.25% Revolving credit facility - due 2020 141,000 209,000 Total long-term debt and revolving credit facility $ 213,765 $ 300,124
Future payments under long-term debt obligations	December 31, 2017 , future payments under long-term debt obligations over each of the next three years are as follows: 2016 Credit Facility 2018 18,750 2019 18,750 2020 195,687 Minimum future payments of principal 233,187 Less debt issuance costs 672 Current portion of long-term debt 18,750 Long-term debt and revolving credit facility $ 213,765
Accumulated OCI Balance Attributable to Cash Flow Derivatives	The following table summarizes the effects of ASC 815 on the Company's accumulated OCI balance attributable to cash flow derivatives: Year Ended December 31 2017 Accumulated OCI beginning balance $ — Mark-to-market of cash flow hedge accounting contracts 965 Accumulated OCI ending balance, net of tax of $320 $ 965 Gains expected to be realized from accumulated OCI during the next 12 months $ —

Fair Value of Financial Instr36

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the assets and liabilities that are measured and recognized at fair value on a recurring basis classified under the appropriate level of the fair value hierarchy as of December 31, 2017 and December 31, 2016 : December 31, 2017 December 31, 2016 Level 1 Measurements Money market fund (1) $ — $ 300 Level 2 Measurements Available-for-sale securities (2) $ — $ 601 Interest rate swaps (3) $ 1,285 $ — (1) Included in cash and cash equivalents on our consolidated balance sheet. (2) Included in marketable securities on our consolidated balance sheet. (3) Included in other liabilities on our consolidated balance sheet.

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Common stock repurchases	We repurchased the following shares of common stock with cash resources under the 2014 $100,000 repurchase program as of December 31, 2017 and 2016 : December 31, 2017 December 31, 2016 Shares of common stock repurchased 1,599 7,400 Value of common stock repurchased $ 9,510 $ 32,762

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Assumptions used to value options	The fair value for these options was estimated at the date of grant using a Black-Scholes option-pricing model. The assumptions used to value options are as follows: 2017 2016 2015 Risk-free interest rate 1.95-2.18% 1.17-2.12% 1.38-1.80% Expected stock price volatility 46.19-47.59% 47.52-72.50% 73.55-83.14% Dividend yield 0.00 % 0.00 % 0.00 % Expected life (in years) 6.25 6.25 6.25
Payout schedule	For the market-based restricted performance stock units issued during the year ended December 31, 2017 and 2016, the payouts at vesting which are linearly interpolated between the percentiles specified below are as follows: Payout Schedule Percentile Ranking % of Target Earned Greater than 80% 200% 50 % — 80% 100 % — 200% 30 % — 50% 50 % — 100% Less than 30% — % —%
Assumptions made on restricted performance stock units	The assumptions used to value these market based restricted performance stock units are as follows: 2017 2016 2015 Risk-free interest rate 1.54 % 1.12 % 0.98 % Expected stock price volatility 35.99 % 42.61 % 40.21 % Dividend yield 0.00 % 0.00 % 0.00 % Expected term (in years) 2.79 2.79 2.79
Summary of stock incentive plans	Our stock incentive plans as of December 31, 2017 are summarized as follows (in thousands): Shares Authorized Shares Available for Grant Stock Options Outstanding Non-vested Restricted Stock and Restricted Stock Units Options assumed from acquisition 2,227 377 594 685 2006 Incentive Plan 71,669 — 8,576 2,226 2015 Incentive Plan 21,731 11,455 1,278 9,017 Total as of December 31, 2017 95,627 11,832 10,448 11,928
Summary of stock option activities	The following table summarizes the activity and changes related to stock options during the year: Stock Options Outstanding Units Weighted Average Exercise Price Per Unit (in thousands) Outstanding at December 31, 2016 17,580 $ 2.82 Stock options granted 1,022 6.46 Stock options exercised (7,734 ) 2.81 Stock options canceled (420 ) 2.75 Outstanding at December 31, 2017 10,448 $ 3.19 Exercisable at December 31, 2017 7,875 $ 2.78
Summary of restricted stock and restricted stock unit activities	The following table summarizes the activity and changes related to restricted stock and restricted stock units during the year: Restricted Stock and Restricted Stock Units Outstanding Units Weighted Average Grant Date Fair Market Value Per Unit (in thousands) Non-vested at December 31, 2016 15,923 5.04 Restricted stocks and restricted stock units granted 6,599 6.79 Restricted stocks and restricted stock units vested (8,145 ) 5.02 Restricted stocks and restricted stock units canceled (2,449 ) 5.16 Non-vested at December 31, 2017 11,928 $ 5.94
Information regarding options outstanding by exercise price range	Information regarding the options outstanding as of December 31, 2017 is summarized below: Stock Options Outstanding Stock Options Exercisable Range of Exercise Prices Stock Options Outstanding Weighted Average Remaining Contractual Life Weighted Average Exercise Price Aggregate Intrinsic Value Stock Options Vested and Exercisable Weighted Average Remaining Contractual Life Weighted Average Exercise Price Aggregate Intrinsic Value (in thousands) (in years) (in thousands) (in thousands) (in years) (in thousands) $0.33 to $1.43 2,734 1.32 2,317 1.34 $1.44 to $1.99 12 1.72 12 1.72 $2.00 to $4.00 5,779 3.25 4,773 3.18 $4.01 to $7.34 1,923 5.68 773 4.68 10,448 4.97 3.19 $ 72,950 7,875 3.96 2.78 $ 58,181

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future payments under capital leases and minimum payments under non-cancelable operating leases	At December 31, 2017 , future payments under capital leases and minimum payments under non-cancelable operating leases are as follows over each of the next five years and thereafter: Capital Leases Operating Leases Committed Sub-lease Income Net Operating Leases 2018 $ 140 $ 12,094 $ (613 ) $ 11,481 2019 — 11,662 (613 ) $ 11,049 2020 — 10,576 (613 ) $ 9,963 2021 — 7,019 (613 ) $ 6,406 2022 — 6,648 (613 ) $ 6,035 Thereafter — 13,403 (409 ) $ 12,994 Total minimum payments required 140 $ 61,402 $ (3,474 ) $ 57,928

Acquisitions and Dispositiions

Acquisitions and Dispositiions (Tables)	12 Months Ended
	Dec. 31, 2017
Business Acquisition [Line Items]
Schedule of allocated acquisition costs	The consideration was allocated to acquisition cost as follows: Cash paid at closing (inclusive of cash acquired of $16,094) $ 179,186 Stock paid at closing 31,591 Variable Payout Amount (described below) 16,472 Employee Payout Amount (described below) 4,779 Acquisition Cost $ 232,028
Intangible Assets Acquired	The intangible assets as of the closing date of the acquisition included: Customer relationships $ 85,900 Developed technologies 13,768 Non-compete agreements 972 Trade names 1,130 $ 101,770
Pro forma financial information	Pro forma financial information (unaudited) The following unaudited supplemental pro forma information presents the combined historical results of operations of Vonage and Nexmo for the years ended December 31, 2016 and 2015, as if the acquisition had been completed at January 1, 2015. For the years ended December 31, 2016 December 31, 2015 Revenue $ 989,846 $ 958,416 Net income attributable to Vonage 8,403 5,679 Net income attributable to Vonage per share - basic 0.04 0.03 Net income attributable to Vonage per share - diluted 0.04 0.02
Nexmo
Business Acquisition [Line Items]
Estimated fair values of assets acquired and liabilities assumed	The table below summarizes the Nexmo assets acquired and liabilities assumed as of June 3, 2016: Acquisition Date Fair Value as of December 31, 2016 Measurement period adjustments Revised Acquisition Date Fair Value Assets Current assets: Cash and cash equivalents $ 16,094 $ — $ 16,094 Accounts receivable 8,764 — 8,764 Prepaid expenses and other current assets 3,507 — 3,507 Total current assets 28,365 — 28,365 Property and equipment 757 — 757 Software, net 242 — 242 Intangible assets 101,770 — 101,770 Restricted cash 51 — 51 Total assets acquired 131,185 — 131,185 Liabilities Current liabilities: Accounts payable 1,841 — 1,841 Accrued expenses 9,299 — 9,299 Deferred revenue, current portion 1,735 — 1,735 Total current liabilities 12,875 — 12,875 Deferred tax liabilities, net, non-current 29,355 (5,482 ) 23,873 Total liabilities assumed 42,230 (5,482 ) 36,748 Net identifiable assets acquired 88,955 5,482 94,437 Goodwill 143,073 (5,482 ) 137,591 Total purchase price $ 232,028 $ — $ 232,028
iCore
Business Acquisition [Line Items]
Estimated fair values of assets acquired and liabilities assumed	The table below summarizes the iCore assets acquired and liabilities assumed as of August 31, 2015: Acquisition Date Fair Value Assets Current assets: Cash and cash equivalents $ 1,014 Current assets 2,700 Total current assets 3,714 Property and equipment 4,437 Intangible assets 38,064 Other assets 659 Total assets acquired 46,874 Liabilities Current liabilities: Accounts payable 3,344 Accrued expenses 3,979 Deferred revenue, current portion 576 Current maturities of capital lease obligations 557 Total current liabilities 8,456 Capital lease obligations, net of current maturities 552 Deferred tax liabilities, net, non-current 8,487 Total liabilities assumed 17,495 Net identifiable assets acquired 29,379 Goodwill 63,310 Total purchase price $ 92,689
Simple Signal
Business Acquisition [Line Items]
Estimated fair values of assets acquired and liabilities assumed	The table below summarizes the Simple Signal assets acquired and liabilities assumed as of April 1, 2015: Acquisition Date Fair Value Assets Current assets: Cash and cash equivalents $ 53 Current assets 1,042 Total current assets 1,095 Property and equipment 979 Software 401 Intangible assets 6,407 Deferred tax assets, net, non-current 741 Total assets acquired 9,623 Liabilities Current liabilities: Accounts payable 785 Accrued expenses 593 Deferred revenue, current portion 370 Total current liabilities 1,748 Total liabilities assumed 1,748 Net identifiable assets acquired 7,875 Goodwill 17,703 Total purchase price $ 25,578

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property and Equipment:
Property, Plant and Equipment	December 31, 2017 December 31, 2016 Network equipment and computer hardware $ 79,990 $ 93,437 Building (under capital lease through August 31, 2017) — 25,709 Leasehold improvements 36,987 44,293 Customer premise equipment 12,884 9,700 Furniture 4,668 4,239 Vehicles 17 203 134,546 177,581 Less accumulated depreciation (87,792 ) (129,166 ) Property, plant and equipment 46,754 48,415

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Accrued Liabilities [Abstract]
Schedule of Accrued Liabilities [Table Text Block]	December 31, 2017 December 31, 2016 Compensation and benefits, related taxes and temporary labor $ 30,059 $ 35,525 Marketing 10,759 12,754 Taxes and fees 13,353 19,234 Acquisition related consideration accounted for as compensation 2,534 6,608 Telecommunications 16,068 14,896 Settlement — 5,000 Other accruals 6,782 10,256 Customer credits 2,310 2,074 Professional fees 1,618 1,680 Inventory 1,927 1,168 $ 85,410 $ 109,195

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Summary of the results from discontinued operations	The results of operations of this discontinued operation are as follows: For the year ended December 31, 2015 Revenues $ 33 Operating expenses 1,648 Loss from discontinued operations (1,615 ) Loss on disposal, net of taxes (824 ) Net loss from discontinued operations (2,439 ) Plus: Net loss from discontinued operations attributable to noncontrolling interest 59 Net loss from discontinued operations attributable to Vonage $ (2,380 )

Industry Segment and Geograph44

Industry Segment and Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of results by segment	Information about our segment results for the years ended December 31, 2017 , 2016 , and 2015 were as follows: Year ended December 31, 2017 Business Consumer Total Revenues Service revenues $ 419,591 $ 454,340 $ 873,931 Product revenues (1) 52,498 525 53,023 Service and product revenues 472,089 454,865 926,954 USF revenues 26,833 48,499 75,332 Total revenues 498,922 503,364 1,002,286 Cost of revenues Service cost of revenues (2) 190,934 80,454 271,388 Product cost of revenues (1) 51,026 7,208 58,234 Service and product cost of revenues 241,960 87,662 329,622 USF cost of revenues 26,833 48,499 75,332 Total cost of revenues 268,793 136,161 404,954 Segment gross margin Service margin 228,657 373,886 602,543 Product margin 1,472 (6,683 ) (5,211 ) Gross margin ex-USF (Service and product margin) 230,129 367,203 597,332 USF margin — — — Total segment gross margin $ 230,129 $ 367,203 $ 597,332 Segment gross margin % Service margin % 54.5 % 82.3 % 68.9 % Gross margin ex-USF (Service and product margin %) 48.7 % 80.7 % 64.4 % Segment gross margin % 46.1 % 72.9 % 59.6 % (1) Includes customer premise equipment, access, professional services, and shipping and handling. (2) Excludes depreciation and amortization of $20,100 , $7,208 , and $27,308 , respectively. Year ended December 31, 2016 Business Consumer Total Revenues Service revenues $ 301,877 $ 522,515 $ 824,392 Product revenues (1) 52,450 702 53,152 Service and product revenues 354,327 523,217 877,544 USF revenues 22,025 56,052 78,077 Total revenues 376,352 579,269 955,621 Cost of revenues Service cost of revenues (2) 111,485 100,054 211,539 Product cost of revenues (1) 51,129 14,394 65,523 Service and product cost of revenues 162,614 114,448 277,062 USF cost of revenues 22,036 56,052 78,088 Total cost of revenues 184,650 170,500 355,150 Segment gross margin Service margin 190,392 422,461 612,853 Product margin 1,321 (13,692 ) (12,371 ) Gross margin ex-USF (Service and product margin) 191,713 408,769 600,482 USF gross margin (11 ) — (11 ) Total segment gross margin $ 191,702 $ 408,769 $ 600,471 Segment gross margin % Service margin % 63.1 % 80.9 % 74.3 % Gross margin ex-USF (Service and product margin %) 54.1 % 78.1 % 68.4 % Segment gross margin % 50.9 % 70.6 % 62.8 % (1) Includes customer premise equipment, access, professional services, and shipping and handling. (2) Excludes depreciation and amortization of $18,820 , $9,669 , and $28,489 , respectively. Year ended December 31, 2015 Business Consumer Total Revenues Service revenues $ 170,489 $ 612,822 $ 783,311 Product revenues (1) 35,545 645 36,190 Service and product revenues 206,034 613,467 819,501 USF revenues 12,993 62,578 75,571 Total revenues 219,027 676,045 895,072 Cost of revenues Service cost of revenues (2) 44,997 123,580 168,577 Product cost of revenues (1) 31,185 20,616 51,801 Service and product cost of revenues 76,182 144,196 220,378 USF cost of revenues 13,022 62,578 75,600 Total cost of revenues 89,204 206,774 295,978 Segment gross margin Service margin 125,492 489,242 614,734 Product margin 4,360 (19,971 ) (15,611 ) Gross margin ex-USF (Service and product margin) 129,852 469,271 599,123 USF margin (29 ) — (29 ) Total segment gross margin $ 129,823 $ 469,271 $ 599,094 Segment gross margin % Service margin % 73.6 % 79.8 % 78.5 % Gross margin ex-USF (Service and product margin %) 63.0 % 76.5 % 73.1 % Segment gross margin % 59.3 % 69.4 % 66.9 % (1) Includes customer premise equipment, access, professional services, and shipping and handling. (2) Excludes depreciation and amortization of $15,819 , $9,049 , and $24,868 , respectively. A reconciliation of the total of the reportable segments' gross margin to consolidated income before provision for income taxes is as follows: Years Ended December 31, 2017 2016 2015 Total reportable gross margin $ 597,332 $ 600,471 $ 599,094 Sales and marketing 313,251 330,969 347,896 Engineering and development 29,630 29,759 27,220 General and administrative 122,537 123,304 109,153 Depreciation and amortization 72,523 72,285 61,833 Income from operations 59,391 44,154 52,992 Interest income 17 79 89 Interest expense (14,868 ) (13,042 ) (8,786 ) Other income (expense), net 1,253 (346 ) (842 ) Income before income taxes $ 45,793 $ 30,845 $ 43,453 Information about our operations by geographic location is as follows: For the years ended December 31, 2017 2016 2015 Revenues: United States $ 851,413 $ 872,147 $ 854,706 Canada 30,252 27,417 25,935 United Kingdom 28,309 17,365 14,431 Other Countries (1) 92,312 38,692 — $ 1,002,286 $ 955,621 $ 895,072 (1) No individual other international country represented greater than 9% of total revenue during the periods presented.
Schedule of long lived assets by geographic area	December 31, 2017 December 31, 2016 Long-lived assets: United States $ 615,432 $ 629,269 United Kingdom 365 450 Israel 243 286 $ 616,040 $ 630,005

Cash Flow Information (Tables)

Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Detail of supplemental disclosures for cash flow and non-cash investing and financing information was For the years ended December 31, (In thousands) 2017 2016 2015 Supplemental disclosures of cash flow information: Cash paid during the periods for: Interest $ 13,323 $ 11,621 $ 7,834 Income taxes 6,760 5,335 2,516 Non-cash investing and financing activities: Capital expenditures included in accounts payable and accrued liabilities $ 2,345 $ 3,610 $ 8,741 Issuance of common stock in connection with acquisition of business — 31,591 5,578 Purchase of intangible assets — — 5,000 Contingent consideration in connection with acquisition of business — 16,472 — Assumption of options in connection with acquisition of business — 4,779 —

Quarterly Financial Informati46

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly financial information	: March 31, June 30, September 30, December 31, Year Ended 2017 Revenue 243,347 251,836 253,083 254,020 Income from operations 5,124 6,659 24,623 22,985 Net income attributable to Vonage 5,913 4,825 10,602 (55,273 ) Net income attributable to Vonage per common share: Basic net income per share Basic net income per share attributable to Vonage 0.03 0.02 0.05 (0.24 ) Diluted net income per share Diluted net income per share attributable to Vonage 0.02 0.02 0.04 (0.24 ) Year Ended 2016 (1) Revenue 226,824 233,675 248,359 246,763 Income from operations 18,524 5,387 15,029 5,214 Net income attributable to Vonage 7,931 218 7,040 (2,038 ) Net income attributable to Vonage per common share: Basic net income per share Basic net income per share attributable to Vonage 0.04 — 0.03 (0.01 ) Diluted net income per share Diluted net income per share attributable to Vonage 0.04 — 0.03 (0.01 )

Nature of Business (Details)

Nature of Business (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
United States
Concentration risk:
Customer Representation Of Revenue, Percentage	85.00%	91.00%	95.00%

Summary of Significant Accoun48

Summary of Significant Accounting Policies - Narrative (Details) number in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)billing_cycle	Dec. 31, 2016USD ($)		Dec. 31, 2015USD ($)		Dec. 31, 2014USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount		$ 11,000,000
Cost of services (excluding depreciation and amortization)		27,308,000	$ 28,489,000		$ 24,868,000
Sales and marketing		313,251,000	330,969,000		347,896,000
Engineering and development		$ 29,630,000	29,759,000		27,220,000
Maximum original maturity term of investments to be considered cash and cash equivalents		3 months
Number of unsuccessful billing cycles before account termination | billing_cycle		3
Restricted cash		$ 1,967,000	1,851,000		2,587,000		$ 3,405,000
Effective income tax rate reconciliation, change in enacted tax rate, amount		69,378,000
Foreign currency transaction gain (loss), before tax		620,000	346,000		860,000
Net cash used in investing activities		(30,737,000)	(191,449,000)	[1]	(153,509,000)	[1]
Effect of exchange rate changes on cash		1,319,000	555,000	[1]	(316,000)	[1]
Cash and cash equivalents		31,360,000	29,078,000		57,726,000		40,797,000
Cash, cash equivalents, restricted cash and restricted cash equivalents		33,327,000	30,929,000	[1]	60,313,000	[1]	$ 44,202,000	[1]
Net cash provided by operating activities		128,058,000	93,456,000	[1]	134,485,000	[1]
Employee Severance
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restructuring Costs		5,101,000
Restructuring reserve, current		1,090,000
Payments for restructuring		4,011,000
Alternative Minimum Tax
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective income tax rate reconciliation, change in enacted tax rate, amount		8,217,000
Other Assets | Alternative Minimum Tax
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other current assets		$ 4,108,000
Customer premise equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life of property and equipment		3 years
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Software, useful fife		2 years
Minimum | Network equipment and computer hardware
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life of property and equipment		3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Software, useful fife		5 years
Maximum | Network equipment and computer hardware
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Useful life of property and equipment		5 years
Purchased Intangible Assets | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible asset useful life		2 years
Purchased Intangible Assets | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible asset useful life		10 years
New product development
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Engineering and development		$ 23,730,000	22,447,000		18,350,000
Selling and Marketing Expense
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales and marketing		57,703,000	75,587,000		103,320,000
Letter of credit-lease deposits
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash		1,563,000	1,578,000
Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by operating activities			6,444,000		4,754,000
Accumulated Deficit | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement or change in accounting principle, effect of adoption, quantification	$ 5,668,000
State and local taxes, net of federal benefit	228500.00%
Deferred Tax Assets | Accounting Standards Update 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New accounting pronouncement or change in accounting principle, effect of adoption, quantification	$ 6,624,000
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities			716,000		813,000
Effect of exchange rate changes on cash			$ 20,000		$ 5,000
Adjustment | Accounting Standards Update 2014-09 | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		35,000,000
Adjustment | Accounting Standards Update 2014-09 | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 40,000,000
[1]	(1) See Note 2. Summary of Significant Accounting Policies for reclassification due to the adoptions of new Accounting Standard Updates and Note 3. Correction of Prior Period Financial Statements.

Correction of Prior Period Fi49

Correction of Prior Period Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2016		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015	Mar. 31, 2017	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Deferred tax assets	$ 184,210	[1]	$ 110,892	$ 184,210	[1]
Assets	935,666	[1]	858,681	935,666	[1]
Accumulated deficit	(641,869)	[1]	(672,561)	(641,869)	[1]
Stockholders' Equity Attributable to Parent	436,541	[1]	472,898	436,541	[1]	$ 388,741		$ 343,497
Liabilities and Equity	935,666	[1]	858,681	935,666	[1]
Income Tax Expense (Benefit)	(3,592)		(79,726)	(17,694)	[2]	(18,418)
Net (loss)/income attributable to Vonage	$ (2,038)		$ (33,933)	$ 13,151	[2]	$ 22,655
Basic net (loss)/income per share - attributable to Vonage	$ (0.01)		$ (0.15)	$ 0.06	[2]	$ 0.11
Diluted net (loss)/income per share - attributable to Vonage	$ (0.01)		$ (0.15)	$ 0.06	[2]	$ 0.10
Scenario, Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Deferred tax assets	$ 188,966			$ 188,966
Assets	940,422			940,422
Accumulated deficit	(637,113)			(637,113)
Stockholders' Equity Attributable to Parent	441,297			441,297
Liabilities and Equity	940,422			940,422
Income Tax Expense (Benefit)	(1,553)			(12,938)
Net (loss)/income attributable to Vonage	$ 1			$ 17,907
Basic net (loss)/income per share - attributable to Vonage	$ 0			$ 0.08
Diluted net (loss)/income per share - attributable to Vonage	$ 0			$ 0.08
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Deferred tax assets	$ 4,756			$ 4,756
Assets	4,756			4,756
Accumulated deficit	4,756			4,756			$ 4,756
Stockholders' Equity Attributable to Parent	4,756			4,756
Liabilities and Equity	4,756			4,756
Income Tax Expense (Benefit)	2,039			4,756
Net (loss)/income attributable to Vonage	$ 2,039			$ 4,756
Basic net (loss)/income per share - attributable to Vonage	$ 0.01			$ 0.02
Diluted net (loss)/income per share - attributable to Vonage	$ 0.01			$ 0.02
[1]	(1) see Note 3. Correction of Prior Period Financial Statements.
[2]	(1) see Note 3. Correction of Prior Period Financial Statements

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Vonage	$ (55,273)	$ 10,602	$ 4,825	$ 5,913	$ (2,038)	[1]	$ 7,040	[1]	$ 218	[1]	$ 7,931	[1]	$ (33,933)	$ 13,151	[2]	$ 25,035
Discontinued operations													0	0		(2,439)
Plus: Net loss from discontinued operations attributable to noncontrolling interest													0	0		(59)
Loss from discontinued operations attributable to Vonage													0	0		(2,380)
Net (loss)/income attributable to Vonage					$ (2,038)								$ (33,933)	$ 13,151	[2]	$ 22,655
Basic weighted average common shares outstanding													225,311	215,751		213,147
Diluted weighted average common shares outstanding													0	16,190		10,963
Diluted weighted average common shares outstanding													225,311	231,941		224,110
Basic net (loss)/income per share - from continuing operations	$ (0.24)	$ 0.05	$ 0.02	$ 0.03	$ (0.01)		$ 0.03		$ 0		$ 0.04		$ (0.15)	$ 0.06	[2]	$ 0.12
Basic net loss per share - from discontinued operations attributable to Vonage													0	0		(0.01)
Basic net (loss)/income per share - attributable to Vonage					(0.01)								(0.15)	0.06	[2]	0.11
Diluted net (loss)/income per share - from continuing operations	$ (0.24)	$ 0.04	$ 0.02	$ 0.02	(0.01)		$ 0.03		$ 0		$ 0.04		(0.15)	0.06	[2]	0.11
Diluted net loss per share - from discontinued operations attributable to Vonage													0	0		(0.01)
Diluted net (loss)/income per share - attributable to Vonage					$ (0.01)								$ (0.15)	$ 0.06	[2]	$ 0.10
[1]	(1) see Note 3. Correction of Prior Period Financial Statements
[2]	(1) see Note 3. Correction of Prior Period Financial Statements

Earnings Per Share Antidilutive

Earnings Per Share Antidilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings per share, antidilutive securities:
Antidilutive securities excluded from earnings per common share	22,376	17,312	19,427
Restricted stock units
Earnings per share, antidilutive securities:
Antidilutive securities excluded from earnings per common share	11,928	8,282	5,827
Employee stock options
Earnings per share, antidilutive securities:
Antidilutive securities excluded from earnings per common share	10,448	9,030	13,600

Goodwill and Intangible Asset52

Goodwill and Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 360,363	$ 222,106
Currency translation adjustments	18,883	7,146
Goodwill, end of period	373,764	360,363
Simple Signal
Goodwill [Roll Forward]
Increase for goodwill acquired		16
iCore
Goodwill [Roll Forward]
Increase for goodwill acquired		2,314
Nexmo
Goodwill [Roll Forward]
Goodwill, beginning of period	143,073
Increase for goodwill acquired		143,073
Goodwill, Subsequent Recognition of Deferred Tax Asset	(5,482)
Goodwill, end of period	$ 137,591	$ 143,073

Goodwill and Intangible Asset53

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Intangible assets:
Gross Carrying Value	$ 297,843	$ 287,675
Accumulated Amortization	(124,573)	(88,419)
Net Carrying Value	173,270	199,256
Customer relationships
Intangible assets:
Gross Carrying Value	184,465	173,187
Accumulated Amortization	(62,072)	(39,413)
Net Carrying Value	122,393	133,774
Developed technology
Intangible assets:
Gross Carrying Value	90,417	88,609
Accumulated Amortization	(44,413)	(31,364)
Net Carrying Value	46,004	57,245
Patents and patent licenses
Intangible assets:
Gross Carrying Value	20,214	20,214
Accumulated Amortization	(16,184)	(14,667)
Net Carrying Value	4,030	5,547
Trade names
Intangible assets:
Gross Carrying Value	1,708	1,820
Accumulated Amortization	(1,356)	(787)
Net Carrying Value	$ 352	1,033
Non-compete agreements
Intangible assets:
Intangible asset useful life	3 years
Gross Carrying Value	$ 1,039	3,845
Accumulated Amortization	(548)	(2,188)
Net Carrying Value	$ 491	$ 1,657
Minimum | Customer relationships
Intangible assets:
Intangible asset useful life	7 years
Minimum | Developed technology
Intangible assets:
Intangible asset useful life	3 years
Minimum | Patents and patent licenses
Intangible assets:
Intangible asset useful life	3 years
Minimum | Trade names
Intangible assets:
Intangible asset useful life	2 years
Maximum | Customer relationships
Intangible assets:
Intangible asset useful life	12 years
Maximum | Developed technology
Intangible assets:
Intangible asset useful life	10 years
Maximum | Patents and patent licenses
Intangible assets:
Intangible asset useful life	5 years
Maximum | Trade names
Intangible assets:
Intangible asset useful life	5 years

Goodwill and Intangible Asset54

Goodwill and Intangible Assets - Expected Future Annual Amortization (Details) $ in Thousands	Dec. 31, 2017USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,018	$ 35,747
2,019	32,384
2,020	27,934
2,021	21,985
2,022	$ 17,006

Goodwill and Intangible Asset55

Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible assets:
Amortization of intangibles	$ 38,056	$ 34,634	$ 26,404
Goodwill	$ 373,764	$ 360,363	$ 222,106
Non-compete agreements
Intangible assets:
Intangible asset useful life	3 years
Minimum | Customer relationships
Intangible assets:
Intangible asset useful life	7 years
Minimum | Developed technology
Intangible assets:
Intangible asset useful life	3 years
Minimum | Trade names
Intangible assets:
Intangible asset useful life	2 years
Maximum | Customer relationships
Intangible assets:
Intangible asset useful life	12 years
Maximum | Developed technology
Intangible assets:
Intangible asset useful life	10 years
Maximum | Trade names
Intangible assets:
Intangible asset useful life	5 years
Immaterial correction of acquisition accounting | Adjustment
Intangible assets:
Deferred tax liabilities, net, non-current	$ (2,298)
Goodwill	$ 2,298

Income Taxes - Components of In

Income Taxes - Components of Income Before Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
United States	$ 39,370	$ 31,076	$ 38,115
Foreign	6,423	(231)	5,338
Income from continuing operations before income tax expense	$ 45,793	$ 30,845	$ 43,453

Income Taxes - Components of I

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Current:
Federal		$ (1,101)	$ (621)		$ (1,846)
Foreign		(1,731)	(1,064)		(1,667)
State and local taxes		(2,317)	(3,951)		(956)
Current income tax expense (benefit)		(5,149)	(5,636)		(4,469)
Deferred:
Federal		(75,928)	(12,550)		(11,289)
Foreign		1,631	2		(1,088)
State and local taxes		(280)	490		(1,572)
Deferred income tax expense (benefit)		(74,577)	(12,058)		(13,949)
Income tax expense (benefit)	$ (3,592)	$ (79,726)	$ (17,694)	[1]	$ (18,418)
[1]	(1) see Note 3. Correction of Prior Period Financial Statements

Income Taxes - Income Tax Rate

Income Taxes - Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of income tax rate:
U.S. Federal statutory tax rate	35.00%	35.00%	35.00%
Permanent items	10.00%	10.00%	3.00%
Effect of the Tax Cuts and Jobs Act	152.00%	0.00%	0.00%
Equity-based compensation	(24.00%)	0.00%	0.00%
State and local taxes, net of federal benefit	5.00%	7.00%	2.00%
International tax (reflects effect of losses for which tax benefit not realized)	(4.00%)	0.00%	1.00%
Valuation reserve for income taxes and other	0.00%	5.00%	2.00%
Effective tax rate	174.00%	57.00%	43.00%

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets and liabilities:
Accounts receivable and inventory allowances	$ 553	$ 816
Deferred rent	862	630
Contingent consideration	0	1,482
Acquired intangible assets and property and equipment	(39,077)	(61,486)
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals	5,182	10,145
Research and development and alternative minimum tax credit	958	8,039
Stock option compensation	17,734	24,026
Capital leases	37	(7,762)
Cumulative translation adjustments	(714)	0
Deferred Tax Assets, Deferred Income	6,994	11,362
Deferred Tax Liabilities, Derivatives	(319)	0
Net operating loss carryforwards	141,072	215,504
Deferred Tax Assets, Gross, Noncurrent	133,282	202,756
Valuation allowance	(22,390)	(18,546)
Deferred tax assets	$ 110,892	$ 184,210	[1]
[1]	(1) see Note 3. Correction of Prior Period Financial Statements.

Income Taxes - Net Operating Lo

Income Taxes - Net Operating Loss Carryforwards (Details) $ in Thousands	Dec. 31, 2017USD ($)
Federal
Net operating loss carryforwards:
Net operating loss carryforwards	$ 556,368
State
Net operating loss carryforwards:
Net operating loss carryforwards	$ 146,254

Income Taxes - Uncertain Tax Be

Income Taxes - Uncertain Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Uncertain Tax Benefits [Abstract]
Unrecognized Tax Benefits	$ 1,086	$ 0	$ 0
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	$ 1,086	$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Net operating loss carryforwards:
Effective income tax rate reconciliation, change in enacted tax rate, amount	$ 69,378,000
Deferred tax assets	110,892,000	$ 184,210,000	[1]
Deferred Tax Assets, Valuation Allowance, Noncurrent	22,390,000	18,546,000
Unrecognized Tax Benefits	1,086,000	$ 0		$ 0
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount	11,000,000
Federal
Net operating loss carryforwards:
Net operating loss carryforwards	556,368,000
State
Net operating loss carryforwards:
Net operating loss carryforwards	146,254,000
Foreign Tax Authority | United Kingdom
Net operating loss carryforwards:
Net operating loss carryforwards	$ 50,142,000
[1]	(1) see Note 3. Correction of Prior Period Financial Statements.

Long-Term Debt and Revolving 63

Long-Term Debt and Revolving Credit Facility - Long-term Debt (Details)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
Interest Rate Derivative Assets, at Fair Value	$ 1,285,000
Derivative, Number of Instruments Held	3
Total long-term debt and revolving credit facility	$ 213,765,000	$ 300,124,000
Term Loan | Secured debt | 2016 Credit Facility
Debt Instrument [Line Items]
Total long-term debt and revolving credit facility	72,765,000	91,124,000
Revolving Credit Facility | Line of Credit | 2016 Credit Facility
Debt Instrument [Line Items]
Total long-term debt and revolving credit facility	$ 141,000,000	$ 209,000,000

Long-Term Debt and Revolving 64

Long-Term Debt and Revolving Credit Facility - Future Payments Under Long-term Debt Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt and revolving credit facility	$ 213,765	$ 300,124
Term Loan | Secured debt | 2016 Credit Facility
Debt Instrument [Line Items]
2,018	18,750
2,019	18,750
2,020	195,687
Less debt issuance costs	672
Less: current portion	18,750
Long-term debt and revolving credit facility	72,765	$ 91,124
Term Loan | Secured debt | Credit Facility and Revolver, 2016
Debt Instrument [Line Items]
Minimum future payments of principal	233,187
Long-term debt and revolving credit facility	$ 213,765

Long-Term Debt and Revolving 65

Long-Term Debt and Revolving Credit Facility - Interest Rate Swap (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated OCI beginning balance	$ 0
Unrealized gain on derivatives	965	$ 0	$ 0
Accumulated OCI ending balance	965	0
Gains expected to be realized from accumulated OCI during the next 12 months	0
Unrealized Gain on Derivatives, Tax	320	$ 0	$ 0
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Unrealized gain on derivatives	965
Unrealized Gain on Derivatives, Tax	$ 320

Long-Term Debt and Revolving 66

Long-Term Debt and Revolving Credit Facility - Narrative (Details) - USD ($)	Jun. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Interest Rate Derivative Assets, at Fair Value		$ 1,285,000
Proceeds received from draw down of revolving credit facility and issuance of notes payable		$ 15,000,000	$ 181,250,000	$ 102,000,000
Derivative, Number of Instruments Held		3
Derivative, Amount of Hedged Item		$ 150,000,000
Derivative, Fixed Interest Rate		4.70%
2016 Credit Facility
Debt Instrument [Line Items]
Debt related costs related to Revolving Credit Facility	$ 1,316,000
2016 Credit Facility | Nexmo
Debt Instrument [Line Items]
Proceeds used in acquisition	$ 179,000,000
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term One | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term One | Maximum | LIBOR
Debt Instrument [Line Items]
Consolidated leverage ratio	75.00%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Two | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Two | Minimum | LIBOR
Debt Instrument [Line Items]
Consolidated leverage ratio	75.00%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Two | Maximum | LIBOR
Debt Instrument [Line Items]
Consolidated leverage ratio	150.00%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Three | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	3.00%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Three | Minimum | LIBOR
Debt Instrument [Line Items]
Consolidated leverage ratio	150.00%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Three | Maximum | LIBOR
Debt Instrument [Line Items]
Consolidated leverage ratio	250.00%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Four | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	3.25%
2016 Credit Facility | LIBOR Rate Option | Leverage Ratio, Term Four | Minimum | LIBOR
Debt Instrument [Line Items]
Consolidated leverage ratio	250.00%
2016 Credit Facility | Base Rate Option | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
2016 Credit Facility | Base Rate Option | Federal Funds
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
2016 Credit Facility | Base Rate Option | Leverage Ratio, Term One | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
2016 Credit Facility | Base Rate Option | Leverage Ratio, Term Two | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%
2016 Credit Facility | Base Rate Option | Leverage Ratio, Term Three | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
2016 Credit Facility | Base Rate Option | Leverage Ratio, Term Four | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.25%
2015 Credit Facility
Debt Instrument [Line Items]
Repayments of debt	$ 197,750,000
Debt related costs related to Revolving Credit Facility	2,740,000
Revolving Credit Facility | Line of Credit | 2016 Credit Facility
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	325,000,000
Repayments of debt		$ 83,000,000
Debt related costs related to Revolving Credit Facility	$ 921,000
Unused capacity, commitment fee, percent	0.45%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term One
Debt Instrument [Line Items]
Unused capacity, commitment fee, percent	0.40%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term One | Minimum
Debt Instrument [Line Items]
Consolidated leverage ratio	150.00%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term One | Maximum
Debt Instrument [Line Items]
Consolidated leverage ratio	250.00%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term Two
Debt Instrument [Line Items]
Unused capacity, commitment fee, percent	0.375%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term Two | Minimum
Debt Instrument [Line Items]
Consolidated leverage ratio	75.00%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term Two | Maximum
Debt Instrument [Line Items]
Consolidated leverage ratio	150.00%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term Three
Debt Instrument [Line Items]
Unused capacity, commitment fee, percent	0.35%
Revolving Credit Facility | Line of Credit | 2016 Credit Facility | Leverage Ratio, Term Three | Maximum
Debt Instrument [Line Items]
Consolidated leverage ratio	75.00%
Revolving Credit Facility | Line of Credit | 2015 Credit Facility
Debt Instrument [Line Items]
Debt related costs related to Revolving Credit Facility	$ 1,810,000
Term Loan | Secured debt | 2016 Credit Facility
Debt Instrument [Line Items]
Debt instrument, face amount	125,000,000
Repayments of debt		$ 18,750,000
Debt related costs related to Revolving Credit Facility	395,000
Periodic payment	4,688,000
Term Loan | Secured debt | 2015 Credit Facility
Debt Instrument [Line Items]
Debt related costs related to Revolving Credit Facility	$ 930,000

Fair Value of Financial Instr67

Fair Value of Financial Instruments Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	$ 1,285
Fair Value, Measurements, Recurring | Level 1 Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market fund	0	$ 300
Fair Value, Measurements, Recurring | Level 2 Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	601
Interest Rate Derivative Assets, at Fair Value	$ 1,285	$ 0

Common Stock - Narrative (Detai

Common Stock - Narrative (Details) - USD ($)	Dec. 09, 2014	Dec. 31, 2017	Dec. 31, 2016
Common stock repurchases:
Common stock, shares authorized		596,950,000	596,950,000
$100,000 repurchase program
Common stock repurchases:
Authorized amount of stock repurchase	$ 100,000,000
Remaining authorized amount of stock repurchase program		$ 42,533,000
Repurchase period	4 years
Common Stock
Common stock repurchases:
Common stock, shares authorized		596,950,000

Common Stock - Repurchased Shar

Common Stock - Repurchased Shares of Common Stock (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common stock repurchases:
Value of common stock repurchased	$ 9,542	$ 32,902	$ 15,250
2014 Repurchase Program
Common stock repurchases:
Stock repurchased during period (in shares)	1,599	7,400
Value of common stock repurchased	$ 9,510	$ 32,762

Employee Benefit Plans - Share-

Employee Benefit Plans - Share-based Compensation, Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee stock options
Share-based compensation:
Risk-free interest rate, minimum	1.95%	1.17%	1.38%
Risk-free interest rate, maximum	2.18%	2.12%	1.80%
Expected stock price volatility, minimum	46.19%	47.52%	73.55%
Expected stock price volatility, maximum	47.59%	72.50%	83.14%
Dividend yield	0.00%	0.00%	0.00%
Expected life (in years)	6 years 3 months	6 years 3 months	6 years 3 months
Restricted stock and restricted stock units
Share-based compensation:
Risk-free interest rate	1.54%	1.12%	0.98%
Expected stock price volatility	35.99%	42.61%	40.21%
Dividend yield	0.00%	0.00%	0.00%
Expected life (in years)	2 years 9 months 15 days	2 years 9 months 15 days	2 years 9 months 15 days

Employee Benefit Plans - SBC, T

Employee Benefit Plans - SBC, Total Share Return (Details)	12 Months Ended
	Dec. 31, 2017
Share-based compensation:
% of Target Earned	100.00%
Restricted stock and restricted stock units
Share-based compensation:
% of Target Earned	200.00%
Restricted stock and restricted stock units | Tranche One
Share-based compensation:
Percentile Ranking	30.00%
% of Target Earned	0.00%
Restricted stock and restricted stock units | Tranche Four
Share-based compensation:
Percentile Ranking	80.00%
% of Target Earned	200.00%
Minimum | Restricted stock and restricted stock units | Tranche Two
Share-based compensation:
Percentile Ranking	30.00%
% of Target Earned	50.00%
Minimum | Restricted stock and restricted stock units | Tranche Three
Share-based compensation:
Percentile Ranking	50.00%
% of Target Earned	100.00%
Maximum | Restricted stock and restricted stock units | Tranche Two
Share-based compensation:
Percentile Ranking	50.00%
% of Target Earned	100.00%
Maximum | Restricted stock and restricted stock units | Tranche Three
Share-based compensation:
Percentile Ranking	80.00%
% of Target Earned	200.00%

Employee Benefit Plans - Shar72

Employee Benefit Plans - Share-based Compensation, by Incentive Plan (Details) - shares	Dec. 31, 2017	Dec. 31, 2016
Share-based compensation:
Shares Authorized	95,627,000
Shares Available for Grant	11,832,000
Stock Options Outstanding	10,448,000	17,580,000
Restricted stock and restricted stock units
Share-based compensation:
Stock Options Outstanding	11,928,000	15,923,000
Non-vested Restricted Stock and Restricted Stock Units	11,928,000
Options assumed from acquisition
Share-based compensation:
Shares Authorized	2,227,000
Shares Available for Grant	377,000
Stock Options Outstanding	594,000
Options assumed from acquisition | Restricted stock and restricted stock units
Share-based compensation:
Non-vested Restricted Stock and Restricted Stock Units	685,000
2006 Incentive Plan
Share-based compensation:
Shares Authorized	71,669,000
Shares Available for Grant	0
Stock Options Outstanding	8,576,000
2006 Incentive Plan | Restricted stock and restricted stock units
Share-based compensation:
Non-vested Restricted Stock and Restricted Stock Units	2,226,000
2015 Incentive Plan
Share-based compensation:
Shares Authorized	21,731,000
Shares Available for Grant	11,455,000
Stock Options Outstanding	1,278,000
2015 Incentive Plan | Restricted stock and restricted stock units
Share-based compensation:
Non-vested Restricted Stock and Restricted Stock Units	9,017,000

Employee Benefit Plans - Shar73

Employee Benefit Plans - Share-based Compensation, Award Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options Outstanding, Number of Shares:
Stock options granted (in shares)	1,022
Stock options exercised (in shares)	(7,734)
Stock options canceled (in shares)	(420)
Stock options, outstanding, balance at end of period (in shares)	10,448	17,580
Stock Options Outstanding, Weighted Average Exercise Price Per Share:
Stock options, outstanding, weighted average exercise price, beginning of period (USD per share)	$ 2.82
Stock options granted, weighted average exercise price (USD per share)	6.46	$ 5.91	$ 4.41
Stock options exercised, weighted average exercise price (USD per share)	2.81
Stock options canceled, weighted average exercise price (USD per share)	2.75
Stock options, outstanding, weighted average exercise price, end of period (USD per share)	$ 3.19	2.82
Stock options, exercisable (in shares)	7,875
Stock options, exercisable, weighted average exercise price (USD per share)	$ 2.78
Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Market Value Per Share:
Restricted stocks and restricted stock units, granted, weighted average exercise price (USD per share)		$ 4.93	$ 5.37
Restricted stock and restricted stock units
Stock Options Outstanding, Number of Shares:
Stock options, outstanding, balance at end of period (in shares)	11,928	15,923
Restricted Stock and Restricted Stock Units, Number of Shares:
Restricted stocks and restricted stock units, granted (in shares)	6,599
Restricted stocks and restricted stock units, exercised (in shares)	(8,145)
Restricted stocks and restricted stock units, canceled (in shares)	(2,449)
Restricted stocks and restricted stock units, outstanding, end of period (in shares)	11,928
Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Market Value Per Share:
Restricted stocks and restricted stock units, outstanding, weighted average exercise price, beginning of period (USD per share)	$ 5.04
Restricted stocks and restricted stock units, granted, weighted average exercise price (USD per share)	6.79
Restricted stocks and restricted stock units, exercised, weighted average exercise price (USD per share)	5.02
Restricted stocks and restricted stock units, canceled, weighted average exercise price (USD per share)	5.16
Restricted stocks and restricted stock units, outstanding, weighted average exercise price, end of period (USD per share)	$ 5.94	$ 5.04

Employee Benefit Plans - Range

Employee Benefit Plans - Range of Exercise Prices (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Share-based compensation by range of exercise prices:
Stock Options Outstanding (in shares) | shares	10,448
Stock Options Outstanding, Weighted Average Remaining Contractual Life	4 years 11 months 19 days
Stock Options Outstanding, Weighted Average Exercise Price (USD per share)	$ 3.19
Stock Options Outstanding, Aggregate Intrinsic Value | $	$ 72,950
Stock Options Exercisable, Stock Options Vested and Exercisable (in shares) | shares	7,875
Stock Options Exercisable, Weighted Average Remaining Contractual Life	3 years 11 months 15 days
Stock Options Exercisable, Weighted Average Exercise Price (USD per share)	$ 2.78
Stock Options Exercisable, Aggregate Intrinsic Value | $	$ 58,181
$0.33 to $1.43
Share-based compensation by range of exercise prices:
Stock Options Outstanding (in shares) | shares	2,734
Stock Options Outstanding, Weighted Average Exercise Price (USD per share)	$ 1.32
Stock Options Exercisable, Stock Options Vested and Exercisable (in shares) | shares	2,317
Stock Options Exercisable, Weighted Average Exercise Price (USD per share)	$ 1.34
Range of Exercise Prices, minimum	0.33
Range of Exercise Prices, maximum	$ 1.43
$1.44 to $1.99
Share-based compensation by range of exercise prices:
Stock Options Outstanding (in shares) | shares	12
Stock Options Outstanding, Weighted Average Exercise Price (USD per share)	$ 1.72
Stock Options Exercisable, Stock Options Vested and Exercisable (in shares) | shares	12
Stock Options Exercisable, Weighted Average Exercise Price (USD per share)	$ 1.72
Range of Exercise Prices, minimum	1.44
Range of Exercise Prices, maximum	$ 1.99
$2.00 to $4.00
Share-based compensation by range of exercise prices:
Stock Options Outstanding (in shares) | shares	5,779
Stock Options Outstanding, Weighted Average Exercise Price (USD per share)	$ 3.25
Stock Options Exercisable, Stock Options Vested and Exercisable (in shares) | shares	4,773
Stock Options Exercisable, Weighted Average Exercise Price (USD per share)	$ 3.18
Range of Exercise Prices, minimum	2
Range of Exercise Prices, maximum	$ 4
$4.01 to $7.34
Share-based compensation by range of exercise prices:
Stock Options Outstanding (in shares) | shares	1,923
Stock Options Outstanding, Weighted Average Exercise Price (USD per share)	$ 5.68
Stock Options Exercisable, Stock Options Vested and Exercisable (in shares) | shares	773
Stock Options Exercisable, Weighted Average Exercise Price (USD per share)	$ 4.68
Range of Exercise Prices, minimum	4.01
Range of Exercise Prices, maximum	$ 7.34

Employee Benefit Plans - Narra

Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based compensation:
Award expiration period	10 years
Vesting percentage	100.00%
Shares Authorized	95,627,000
Maximum awards paid annually	$ 5,000,000
Shares Available for Grant	11,832,000
Stock options granted, weighted average exercise price (USD per share)	$ 6.46	$ 5.91	$ 4.41
Restricted stocks and restricted stock units, granted, weighted average exercise price (USD per share)		$ 4.93	$ 5.37
Stock options, exercises in period, aggregate intrinsic value	$ 38,958,000	$ 12,142,000	$ 8,040,000
Stock options, grants in period, weighted average grant date fair value (USD per share)	$ 3.04	$ 3.01	$ 3.09
Total unamortized share-based compensation	$ 29,642,000
Total unamortized share-based compensation, period for recognition	48 months
Maximum employer contribution percentage	50.00%	50.00%	50.00%
Annual contribution limit per employee	$ 6,000	$ 6,000	$ 6,000
Retirement plan expense	$ 5,411,000	$ 5,015,000	$ 3,676,000
Restricted stock and restricted stock units
Share-based compensation:
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Vesting percentage	200.00%
Restricted stocks and restricted stock units, granted, weighted average exercise price (USD per share)	$ 6.79
Restricted stocks and restricted stock units, exercised, aggregate intrinsic value	$ 41,057,000	$ 12,248,000	$ 8,844,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	$ 121,306,000
Employee stock options
Share-based compensation:
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%
Selling, general and administrative expense
Share-based compensation:
Share-based compensation expense	$ 37,482,000	$ 40,682,000	$ 27,541,000
2006 Incentive Plan
Share-based compensation:
Shares Authorized	71,669,000
Shares Available for Grant	0
2015 Incentive Plan
Share-based compensation:
Shares Authorized	21,731,000
Shares Available for Grant	11,455,000
Minimum
Share-based compensation:
Award vesting period	3 years
Award expiration period	5 years
Maximum
Share-based compensation:
Award vesting period	4 years
Award expiration period	10 years
Maximum | Stock option and stock appreciation rights
Share-based compensation:
Shares Authorized	10,000,000
Director [Member] | Maximum | Stock option and stock appreciation rights
Share-based compensation:
Shares Authorized	10,000,000

Commitments and Contingencies -

Commitments and Contingencies - Leases (Details) $ in Thousands	Dec. 31, 2017USD ($)
Capital leases, future minimum payments due:
2,018	$ 140
2,019	0
2,020	0
2,021	0
2,022	0
Thereafter	0
Total minimum payments required	140
Operating Leases
2,018	12,094
2,019	11,662
2,020	10,576
2,021	7,019
2,022	6,648
Thereafter	13,403
Total minimum payments required	61,402
Committed Sub-lease Income
2,018	(613)
2,019	(613)
2,020	(613)
2,021	(613)
2,022	(613)
Thereafter	(409)
Total minimum payments required	(3,474)
Net Operating Leases
2,018	11,481
2,019	11,049
2,020	9,963
2,021	6,406
2,022	6,035
Thereafter	12,994
Total minimum payments required	$ 57,928

Commitments and Contingencies

Commitments and Contingencies - Narrative (Details) $ in Thousands	Feb. 11, 2013Defendant	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Mar. 24, 2005USD ($)
Loss Contingencies [Line Items]
Lessee Leasing Arrangement, Capital Leases, Term Of Contract		12 years 5 months
Operating lease term		74 months
Rent expense		$ 11,429	$ 7,495	$ 6,378
Vendor Commitments:
Total vendor commitments		53,650
2,018		38,956
2,019		11,592
2,020		2,106
2,021		498
2,022		498
Loss Contingency, Damages Sought, Value		162
RPost Holdings Inc. Litigation Case | Pending Litigation | Patent claims
Vendor Commitments:
Number of defendants | Defendant	27
Collection and remittance of state and municipal taxes | Threatened litigation
Vendor Commitments:
Reserve for potential tax liability pending new requirements from state or municipal agencies		1,147
Letter of credit-lease deposits | New Jersey
Loss Contingencies [Line Items]
Restricted cash		1,563			$ 7,350
Standby Letter of Credit
Loss Contingencies [Line Items]
Restricted cash		$ 1,563	$ 1,578

Acquisitions and Dispositiion78

Acquisitions and Dispositiions - Allocated Acquisition Costs (Details) - Nexmo - USD ($) $ in Thousands	Jun. 03, 2016	May 05, 2016
Business Acquisition, Contingent Consideration [Line Items]
Cash paid at closing (inclusive of cash acquired)	$ 179,186
Stock paid at closing	31,591	$ 31,591
Variable Payout Amount	16,472
Employee Payout Amount	4,779
Acquisition Cost	232,028	$ 231,122
Cash acquired in acquisition	$ 16,094

Acquisitions and Dispositiion79

Acquisitions and Dispositiions - Post Acquisition Liabilities To Be Expensed (Details) $ in Thousands	Jun. 03, 2016USD ($)
Nexmo
Business Acquisition [Line Items]
Total	$ 31,087

Acquisitions and Dispositiion80

Acquisitions and Dispositiions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	May 05, 2016	Dec. 31, 2015	Aug. 31, 2015	Apr. 01, 2015
Current liabilities:
Goodwill	$ 373,764	$ 360,363		$ 222,106
Nexmo
Current assets:
Cash and cash equivalents	16,094	16,094	$ 16,094
Accounts receivable	8,764	8,764
Prepaid expenses and other current assets	3,507	3,507
Total current assets	28,365	28,365
Software	242	242
Intangible assets	101,770	101,770
Restricted cash	51	51
Property and equipment	757	757
Total assets acquired	131,185	131,185
Current liabilities:
Accounts payable	1,841	1,841
Accrued expenses	9,299	9,299
Deferred revenue, current portion	1,735	1,735
Total current liabilities	12,875	12,875
Deferred tax liabilities, net, non-current	23,873	29,355
Business Combination Provisional Information, Initial Accounting Incomplete Adjustment, Deferred Tax Liabilities	(5,482)
Total liabilities assumed	36,748	42,230
Business Combination Provisional Information, Initial Accounting Incomplete Adjustment, Assets Acquired and Liabilities Assumed	(5,482)
Net identifiable assets acquired	94,437	88,955
Business Combination Provisional Information, Initial Accounting Incomplete Adjustment, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	5,482
Goodwill	137,591	143,073
Business Combination Provisional Information, Initial Accounting Incomplete Adjustment, Goodwill	(5,482)
Total purchase price	$ 232,028	$ 232,028
iCore
Current assets:
Cash and cash equivalents					$ 1,014
Accounts receivable					2,700
Total current assets					3,714
Intangible assets					38,064
Property and equipment					4,437
Other assets					659
Total assets acquired					46,874
Current liabilities:
Accounts payable					3,344
Accrued expenses					3,979
Deferred revenue, current portion					576
Current maturities of capital lease obligations					557
Total current liabilities					8,456
Deferred tax liabilities, net, non-current					8,487
Capital lease obligations, net of current maturities					552
Total liabilities assumed					17,495
Net identifiable assets acquired					29,379
Goodwill					63,310
Total purchase price					$ 92,689
Simple Signal
Current assets:
Cash and cash equivalents						$ 53
Prepaid expenses and other current assets						1,042
Total current assets						1,095
Software						401
Intangible assets						6,407
Property and equipment						979
Deferred tax assets, net, non-current						741
Total assets acquired						9,623
Current liabilities:
Accounts payable						785
Accrued expenses						593
Deferred revenue, current portion						370
Total current liabilities						1,748
Total liabilities assumed						1,748
Net identifiable assets acquired						7,875
Goodwill						17,703
Total purchase price						$ 25,578

Acquisitions and Dispositiion81

Acquisitions and Dispositiions - Intangible Assets Acquired (Details) - Nexmo $ in Thousands	Jun. 03, 2016USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 101,770
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	85,900
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	13,768
Non-compete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	972
Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets acquired	$ 1,130

Acquisitions and Dispositiion82

Acquisitions and Dispositiions - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Revenue	$ 989,846	$ 958,416
Net income attributable to Vonage	$ 8,403	$ 5,679
Net income attributable to Vonage per share - basic (USD per share)	$ 0.04	$ 0.03
Net income attributable to Vonage per share - diluted (USD per share)	$ 0.04	$ 0.02

Acquisitions and Dispositiion83

Acquisitions and Dispositiions - Narrative (Details) - USD ($) shares in Thousands	Jun. 03, 2016	May 05, 2016	Aug. 31, 2015	Apr. 01, 2015	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015		May 31, 2017
Business Acquisition [Line Items]
Payment for business, net of cash acquired													$ 0	$ 163,042,000	[1]	$ 116,744,000	[1]
Contingent consideration					$ 2,534,000				$ 6,608,000				2,534,000	6,608,000
Change in contingent consideration													0	(16,472,000)		0
Settlement Liabilities, Current					0				5,000,000				0	5,000,000
Net operating loss carryforwards					141,072,000				215,504,000				141,072,000	215,504,000
Amortization of intangibles													38,056,000	34,634,000		26,404,000
Income tax expense									3,592,000				79,726,000	17,694,000	[2]	18,418,000
Interest expense													14,868,000	13,042,000		8,786,000
Total revenues					254,020,000	$ 253,083,000	$ 251,836,000	$ 243,347,000	246,763,000	$ 248,359,000	$ 233,675,000	$ 226,824,000	1,002,286,000	955,621,000		895,072,000
Net loss													$ 33,933,000	(13,151,000)	[2]	$ (22,596,000)
Non-compete agreements
Business Acquisition [Line Items]
Intangible asset useful life													3 years
Nexmo
Business Acquisition [Line Items]
Acquisition Cost	$ 232,028,000	$ 231,122,000
Earn-out opportunity	20,000,000	20,000,000
Consideration transferred excluding restricted cash, restricted stock and stock options		194,684,000
Payment for business, net of cash acquired		163,093,000
Cash and cash equivalents		$ 16,094,000			16,094,000				16,094,000				$ 16,094,000	16,094,000
Acquisition shares issued (in shares)		6,823
Stock paid at closing	$ 31,591,000	$ 31,591,000
Contingent consideration		$ 36,438,000
Performance targets, term	12 months
Settlement Liabilities, Current					5,000,000								5,000,000
Employee Payout Amount	$ 4,779,000
Business Combination, Conditional Payout Terms, Restricted Stock And Assumed Options, Post-acquisition Expense	31,659,000
Allocated Share-based Compensation Expense	31,087,000
Deferred Compensation Share-based Arrangements, Liability To Be Recorded As Interest Expense	572,000
Acquisition related transaction costs													0	5,500,000
Acquisition cash paid	179,186,000
Intangible assets					101,770,000				101,770,000				101,770,000	101,770,000
Deferred tax liabilities, net, non-current					$ 23,873,000				$ 29,355,000				23,873,000	$ 29,355,000
Intangible assets acquired	101,770,000
Nexmo | Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired	85,900,000
Nexmo | Trade names
Business Acquisition [Line Items]
Intangible assets acquired	1,130,000
Nexmo | Developed technology
Business Acquisition [Line Items]
Intangible assets acquired	13,768,000
Nexmo | Non-compete agreements
Business Acquisition [Line Items]
Intangible assets acquired	972,000
Nexmo | 2016 Credit Facility
Business Acquisition [Line Items]
Proceeds used in acquisition	179,000,000
Nexmo | Reported Value Measurement
Business Acquisition [Line Items]
Contingent consideration	17,840,000
Nexmo | Estimate of Fair Value Measurement
Business Acquisition [Line Items]
Contingent consideration	$ 16,472,000
iCore
Business Acquisition [Line Items]
Cash and cash equivalents			$ 1,014,000
Acquisition cash paid			92,689,000
Intangible assets			38,064,000
Deferred tax liabilities, net, non-current			$ 8,487,000
iCore | Trade names
Business Acquisition [Line Items]
Intangible asset useful life			2 years
Simple Signal
Business Acquisition [Line Items]
Acquisition Cost				$ 25,578,000
Cash and cash equivalents				$ 53,000
Acquisition shares issued (in shares)				1,111
Stock paid at closing				$ 5,578,000
Acquisition cash paid				20,000,000
Intangible assets				$ 6,407,000
Simple Signal | Trade names
Business Acquisition [Line Items]
Intangible asset useful life				2 years
Hosted Infrastructure Product Line [Member] | Disposal Group, Not Discontinued Operations [Member]
Business Acquisition [Line Items]
Disposal Group, Including Discontinued Operation, Consideration																		$ 4,000,000
Disposal Group, Including Discontinued Operation, Consideration Received At Closing																		1,000,000
Disposal Group, Including Discontinued Operation, Consideration To Be Received Six Months From Closing																		500,000
Disposal Group, Discontinued Operation, Consideration To Be Received Based On Achievement Of Financial Objectives																		$ 2,500,000
Disposal Group, Including Discontinued Operation, Gain on Sale													$ 1,879,000
[1]	(1) See Note 2. Summary of Significant Accounting Policies for reclassification due to the adoptions of new Accounting Standard Updates and Note 3. Correction of Prior Period Financial Statements.
[2]	(1) see Note 3. Correction of Prior Period Financial Statements

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property and Equipment:
Property, Plant and Equipment, Gross	$ 134,546	$ 177,581
Less accumulated depreciation	(87,792)	(129,166)
Property, plant and equipment	46,754	48,415
Network equipment and computer hardware
Property and Equipment:
Property, Plant and Equipment, Gross	79,990	93,437
Building (under capital lease through August 31, 2017)
Property and Equipment:
Property, Plant and Equipment, Gross	0	25,709
Leasehold improvements
Property and Equipment:
Property, Plant and Equipment, Gross	36,987	44,293
Customer premise equipment
Property and Equipment:
Property, Plant and Equipment, Gross	12,884	9,700
Furniture
Property and Equipment:
Property, Plant and Equipment, Gross	4,668	4,239
Vehicles
Property and Equipment:
Property, Plant and Equipment, Gross	$ 17	$ 203

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Liabilities [Abstract]
Employee-related Liabilities, Current	$ 30,059	$ 35,525
Accrued Marketing Costs, Current	10,759	12,754
Taxes Payable, Current	13,353	19,234
Contingent consideration	2,534	6,608
Accrued Utilities, Current	16,068	14,896
Settlement Liabilities, Current	0	5,000
Other Accrued Liabilities, Current	6,782	10,256
Accrued Customer Credits, Current	2,310	2,074
Accrued Professional Fees, Current	1,618	1,680
Accrued Inventory	1,927	1,168
Accrued expenses	$ 85,410	$ 109,195

Discontinued Operations Results

Discontinued Operations Results of Operations From Discontinued Operation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, net of taxes	$ 0	$ 0	$ (824)
Discontinued operations	0	0	(2,439)
Plus: Net loss from discontinued operations attributable to noncontrolling interest	0	0	59
Loss from discontinued operations attributable to Vonage	$ 0	$ 0	(2,380)
Discontinued Operations | Brazilian Market, Telephony Services and Related Joint Ventures
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues			33
Operating expenses			1,648
Loss from discontinued operations			(1,615)
Loss on disposal, net of taxes			(824)
Discontinued operations			(2,439)
Plus: Net loss from discontinued operations attributable to noncontrolling interest			59
Loss from discontinued operations attributable to Vonage			$ (2,380)

Discontinued Operations Narrati

Discontinued Operations Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, net of taxes	$ 0	$ 0	$ 824
Brazilian Market, Telephony Services and Related Joint Ventures | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, net of taxes			824
Write-off of noncontrolling interest			907
Foreign currency loss on intercompany loan forgiveness			783
Residual cumulative translations			192
Partial offset by tax benefit			$ 1,058

Industry Segment and Geograph88

Industry Segment and Geographic Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment									2
Number of reportable segments | segment									2
Segment Reporting Information [Line Items]
Sales and marketing									$ 313,251	$ 330,969	$ 347,896
Engineering and development									29,630	29,759	27,220
General and administrative									122,537	123,304	109,153
Depreciation and amortization									72,523	72,285	61,833
Income from operations	$ 22,985	$ 24,623	$ 6,659	$ 5,124	$ 5,214	$ 15,029	$ 5,387	$ 18,524	59,391	44,154	52,992
Interest income									17	79	89
Interest expense									14,868	13,042	8,786
Revenue	254,020	$ 253,083	$ 251,836	$ 243,347	246,763	$ 248,359	$ 233,675	$ 226,824	1,002,286	955,621	895,072
Cost of Services									404,954	355,150	295,978
Gross Profit									597,332	600,471	599,094
Long-lived assets	616,040				630,005				616,040	630,005
Cost of services (excluding depreciation and amortization)									$ 27,308	$ 28,489	$ 24,868
Segment gross margin %									59.60%	62.80%	66.90%
Other income/(expense), net									$ 1,253	$ (346)	$ (842)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									45,793	30,845	43,453
United States
Segment Reporting Information [Line Items]
Revenue									851,413	872,147	854,706
Long-lived assets	615,432				629,269				615,432	629,269
Canada
Segment Reporting Information [Line Items]
Revenue									30,252	27,417	25,935
United Kingdom
Segment Reporting Information [Line Items]
Revenue									28,309	17,365	14,431
Long-lived assets	365				450				365	450
Other Countries
Segment Reporting Information [Line Items]
Revenue									92,312	38,692	0
ISRAEL
Segment Reporting Information [Line Items]
Long-lived assets	$ 243				$ 286				243	286
Business Services
Segment Reporting Information [Line Items]
Revenue									498,922	376,352	219,027
Cost of Services									268,793	184,650	89,204
Gross Profit									230,129	191,702	129,823
Cost of services (excluding depreciation and amortization)									$ 20,100	$ 18,820	$ 15,819
Segment gross margin %									46.10%	50.90%	59.30%
Consumer Services
Segment Reporting Information [Line Items]
Revenue									$ 503,364	$ 579,269	$ 676,045
Cost of Services									136,161	170,500	206,774
Gross Profit									367,203	408,769	469,271
Cost of services (excluding depreciation and amortization)									$ 7,208	$ 9,669	$ 9,049
Segment gross margin %									72.90%	70.60%	69.40%
Services
Segment Reporting Information [Line Items]
Revenue									$ 873,931	$ 824,392	$ 783,311
Cost of Services									271,388	211,539	168,577
Gross Profit									$ 602,543	$ 612,853	$ 614,734
Segment gross margin %									68.90%	74.30%	78.50%
Services | Business Services
Segment Reporting Information [Line Items]
Revenue									$ 419,591	$ 301,877	$ 170,489
Cost of Services									190,934	111,485	44,997
Gross Profit									$ 228,657	$ 190,392	$ 125,492
Segment gross margin %									54.50%	63.10%	73.60%
Services | Consumer Services
Segment Reporting Information [Line Items]
Revenue									$ 454,340	$ 522,515	$ 612,822
Cost of Services									80,454	100,054	123,580
Gross Profit									$ 373,886	$ 422,461	$ 489,242
Segment gross margin %									82.30%	80.90%	79.80%
New product development
Segment Reporting Information [Line Items]
Revenue									$ 53,023	$ 53,152	$ 36,190
Cost of Services									58,234	65,523	51,801
Gross Profit									(5,211)	(12,371)	(15,611)
New product development | Business Services
Segment Reporting Information [Line Items]
Revenue									52,498	52,450	35,545
Cost of Services									51,026	51,129	31,185
Gross Profit									1,472	1,321	4,360
New product development | Consumer Services
Segment Reporting Information [Line Items]
Revenue									525	702	645
Cost of Services									7,208	14,394	20,616
Gross Profit									(6,683)	(13,692)	(19,971)
Service and Product
Segment Reporting Information [Line Items]
Revenue									926,954	877,544	819,501
Cost of Services									329,622	277,062	220,378
Gross Profit									$ 597,332	$ 600,482	$ 599,123
Segment gross margin %									64.40%	68.40%	73.10%
Service and Product | Business Services
Segment Reporting Information [Line Items]
Revenue									$ 472,089	$ 354,327	$ 206,034
Cost of Services									241,960	162,614	76,182
Gross Profit									$ 230,129	$ 191,713	$ 129,852
Segment gross margin %									48.70%	54.10%	63.00%
Service and Product | Consumer Services
Segment Reporting Information [Line Items]
Revenue									$ 454,865	$ 523,217	$ 613,467
Cost of Services									87,662	114,448	144,196
Gross Profit									$ 367,203	$ 408,769	$ 469,271
Segment gross margin %									80.70%	78.10%	76.50%
USF
Segment Reporting Information [Line Items]
Revenue									$ 75,332	$ 78,077	$ 75,571
Cost of Services									75,332	78,088	75,600
Gross Profit									0	(11)	(29)
USF | Business Services
Segment Reporting Information [Line Items]
Revenue									26,833	22,025	12,993
Cost of Services									26,833	22,036	13,022
Gross Profit									0	(11)	(29)
USF | Consumer Services
Segment Reporting Information [Line Items]
Revenue									48,499	56,052	62,578
Cost of Services									48,499	56,052	62,578
Gross Profit									0	$ 0	$ 0
Maximum | Other Countries
Segment Reporting Information [Line Items]
Revenue									$ 0

Cash Flow Information (Details)

Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Elements [Abstract]
Interest	$ 13,323	$ 11,621	$ 7,834
Income taxes	6,760	5,335	2,516
Capital expenditures included in accounts payable and accrued liabilities	2,345	3,610	8,741
Issuance of common stock in connection with acquisition of business	0	31,591	5,578
Purchase of intangible assets	0	0	5,000
Contingent consideration in connection with acquisition of business	0	16,472	0
Assumption of options in connection with acquisition of business	$ 0	$ 4,779	$ 0

Quarterly Financial Informati90

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017	Dec. 31, 2016		Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 254,020	$ 253,083	$ 251,836	$ 243,347	$ 246,763		$ 248,359		$ 233,675		$ 226,824		$ 1,002,286	$ 955,621		$ 895,072
Income from operations	22,985	24,623	6,659	5,124	5,214		15,029		5,387		18,524		59,391	44,154		52,992
Net income attributable to Vonage	$ (55,273)	$ 10,602	$ 4,825	$ 5,913	$ (2,038)	[1]	$ 7,040	[1]	$ 218	[1]	$ 7,931	[1]	$ (33,933)	$ 13,151	[2]	$ 25,035
Basic net income per share
Basic net income per share-from continuing operations (USD per share)	$ (0.24)	$ 0.05	$ 0.02	$ 0.03	$ (0.01)		$ 0.03		$ 0		$ 0.04		$ (0.15)	$ 0.06	[2]	$ 0.12
Basic net income per share-from discontinued operations attributable to Vonage (USD per share)													0	0		(0.01)
Basic net (loss)/income per share - attributable to Vonage					(0.01)								(0.15)	0.06	[2]	0.11
Diluted net income per share
Diluted net (loss)/income per share - from continuing operations	$ (0.24)	$ 0.04	$ 0.02	$ 0.02	(0.01)		$ 0.03		$ 0		$ 0.04		(0.15)	0.06	[2]	0.11
Diluted net loss per share - from discontinued operations attributable to Vonage													0	0		(0.01)
Diluted net (loss)/income per share - attributable to Vonage					$ (0.01)								$ (0.15)	$ 0.06	[2]	$ 0.10
[1]	(1) see Note 3. Correction of Prior Period Financial Statements
[2]	(1) see Note 3. Correction of Prior Period Financial Statements