Ribbon Communications Inc - Ordinary Shares 10-K 25 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 13, 2015	Jun. 27, 2014
Document And Entity Information
Entity Registrant Name	SONUS NETWORKS INC
Entity Central Index Key	1105472
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		49,431,461
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$863,783

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$41,157	$72,423
Short-term investments	64,443	138,882
Accounts receivable, net	62,943	64,463
Inventory	22,114	21,793
Deferred income taxes	991	656
Other current assets	15,239	15,073
Total current assets	206,887	313,290
Property and equipment, net	17,845	19,102
Intangible assets, net	22,594	10,091
Goodwill	39,263	32,379
Investments	42,407	34,364
Deferred income taxes	1,043	2,121
Other assets	2,596	6,137
Total assets	332,635	417,484
Current liabilities:
Accounts payable	7,497	11,164
Accrued expenses	32,149	34,026
Current portion of deferred revenue	36,967	41,169
Convertible subordinated note	0	2,380
Current portion of long-term liabilities	794	672
Total current liabilities	77,407	89,411
Deferred revenue	8,009	10,528
Deferred income taxes	1,623	922
Other long-term liabilities	5,246	4,371
Total liabilities	92,285	105,232
Commitments and contingencies (Note 21)
Stockholders' equity:
Preferred stock, $0.01 par value; 1,000,000 shares authorized, none issued and outstanding	0	0
Common stock, $0.001 par value; 120,000,000 shares authorized; 49,357,033 shares issued and outstanding at December 31, 2014; 53,245,218 shares issued and outstanding at December 31, 2013	49	53
Additional paid-in capital	1,226,226	1,280,655
Accumulated deficit	-991,347	-974,492
Accumulated other comprehensive income	5,422	6,036
Total stockholders' equity	240,350	312,252
Total liabilities and stockholders' equity	$332,635	$417,484

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	49,357,033	53,245,218
Common stock, shares outstanding	49,357,033	53,245,218

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue:
Product	$182,455	$167,272	$153,326
Service	113,871	109,461	100,808
Total revenue	296,326	276,733	254,134
Cost of revenue:
Product	60,284	59,235	58,109
Service	42,637	45,038	53,431
Total cost of revenue	102,921	104,273	111,540
Gross profit	193,405	172,460	142,594
Operating expenses:
Research and development	79,396	69,559	67,341
Sales and marketing	80,141	78,365	76,341
General and administrative	43,937	40,107	34,283
Acquisition-related	1,558	93	5,496
Restructuring	5,625	5,411	7,675
Total operating expenses	210,657	193,535	191,136
Loss from operations	-17,252	-21,075	-48,542
Interest income, net	75	405	612
Other income, net	2,536	3	202
Loss before income taxes	-14,641	-20,667	-47,728
Income tax provision	-2,214	-1,452	-2,441
Net loss	($16,855)	($22,119)	($50,169)
Loss per share:
Basic (in dollars per share)	($0.34)	($0.40)	($0.90)
Diluted (in dollars per share)	($0.34)	($0.40)	($0.90)
Shares used to compute loss per share:
Basic (in shares)	50,245	55,686	56,018
Diluted (in shares)	50,245	55,686	56,018

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net loss	($16,855)	($22,119)	($50,169)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	-426	-672	-535
Unrealized loss on available-for-sale marketable securities	-142	-45	-19
Less: Reclassification adjustment for gains included in net loss	-46	0	0
Other comprehensive loss, net of tax	-614	-717	-554
Comprehensive loss, net of tax	($17,469)	($22,836)	($50,723)

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2011	$415,301	$56	$1,310,142	($902,204)	$7,307
Balance (in shares) at Dec. 31, 2011		55,863,679
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in connection with employee stock purchase plan	1,990		1,990
Issuance of common stock in connection with employee stock purchase plan (in shares)		165,381
Exercise of stock options	254		254
Exercise of stock options (in shares)		42,500
Vesting of restricted stock	1		1
Vesting of restricted stock (in shares)		153,505
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations	-342		-342
Shares Paid for Tax Withholding for Share Based Compensation		-32,406
Stock-based compensation expense	8,673		8,673
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.	892		892
Other comprehensive loss	-554				-554
Net loss	-50,169			-50,169
Balance at Dec. 31, 2012	376,046	56	1,321,610	-952,373	6,753
Balance (in shares) at Dec. 31, 2012		56,192,659
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in connection with employee stock purchase plan	2,210		2,210
Issuance of common stock in connection with employee stock purchase plan (in shares)		152,748
Exercise of stock options	2,669	1	2,668
Exercise of stock options (in shares)		260,913
Vesting of restricted stock	1		1
Vesting of restricted stock (in shares)		181,643
Issuance of vested performance-based stock awards	1		1
Issuance of vested performance-based stock awards (in shares)		241,172
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations	-1,300		-1,300
Shares Paid for Tax Withholding for Share Based Compensation		-80,939
Stock-based compensation expense	14,504		14,504
Repurchase of common stock	-59,674	-4	-59,670
Repurchase of common stock, shares		-3,702,978
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.	0
Reclassification of liability to equity for cash bonuses converted to equity awards	631		631
Other comprehensive loss	-717				-717
Net loss	-22,119			-22,119
Balance at Dec. 31, 2013	312,252	53	1,280,655	-974,492	6,036
Balance (in shares) at Dec. 31, 2013	53,245,218	53,245,218
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in connection with employee stock purchase plan	2,882		2,882
Issuance of common stock in connection with employee stock purchase plan (in shares)		180,502
Exercise of stock options	10,117	1	10,116
Exercise of stock options (in shares)		806,385
Vesting of restricted stock	0
Vesting of restricted stock (in shares)		428,674
Issuance of vested performance-based stock awards	0
Issuance of vested performance-based stock awards (in shares)		136,526
Shares of restricted stock returned to the Company under net share settlements to satisfy tax withholding obligations	-2,442		-2,442
Shares Paid for Tax Withholding for Share Based Compensation		-142,399
Stock-based compensation expense	23,914		23,914
Repurchase of common stock	-93,224	-5	-93,219
Repurchase of common stock, shares		-5,297,873
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.	1,671		1,671
Reclassification of liability to equity for cash bonuses converted to equity awards	2,649		2,649
Other comprehensive loss	-614				-614
Net loss	-16,855			-16,855
Balance at Dec. 31, 2014	$240,350	$49	$1,226,226	($991,347)	$5,422
Balance (in shares) at Dec. 31, 2014	49,357,033	49,357,033

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net loss	($16,855)	($22,119)	($50,169)
Adjustments to reconcile net loss to cash flows provided by (used in) operating activities:
Depreciation and amortization of property and equipment	11,488	12,329	12,891
Amortization of intangible assets	4,597	4,546	2,773
Stock-based compensation	23,914	17,873	9,003
Impairment of intangible assets	0	600	0
Write-off of prepaid royalties for software licenses	0	0	7,083
Loss on disposal of property and equipment	292	54	344
Deferred income taxes	885	-553	785
Changes in operating assets and liabilities:
Accounts receivable	4,771	3,536	-8,924
Inventory	5,414	4,150	-7,713
Other operating assets	5,077	6,200	1,669
Accounts payable	-3,759	-555	-4,949
Accrued expenses and other long-term liabilities	1,657	4,768	937
Deferred revenue	-7,439	3,278	-3,039
Net cash provided by (used in) operating activities	30,042	34,107	-39,309
Cash flows from investing activities:
Purchases of property and equipment	-9,541	-6,949	-10,540
Business acquisition, net of cash acquired	-35,022	0	-35,508
Divestiture of business	2,000	0	0
Purchases of marketable securities	-112,800	-182,491	-159,828
Sale/maturities of marketable securities	179,365	196,980	258,278
Proceeds from the sale of fixed assets	268	0	0
Net cash provided by investing activities	24,270	7,540	52,402
Cash flows from financing activities:
Proceeds from sale of common stock in connection with employee stock purchase plan	2,882	1,888	1,693
Proceeds from exercise of stock options	10,117	2,669	254
Payment of tax withholding obligations related to net share settlements of restricted stock awards	-2,442	-1,300	-342
Repurchase of common stock	-93,224	-59,674	0
Principal payments of capital lease obligations	-84	-117	-120
Payment of debt	-2,380	0	-31,824
Net cash used in financing activities	-85,131	-56,534	-30,339
Effect of exchange rate changes on cash and cash equivalents	-447	-694	-201
Net decrease in cash and cash equivalents	-31,266	-15,581	-17,447
Cash and cash equivalents, beginning of year	72,423	88,004	105,451
Cash and cash equivalents, end of period	41,157	72,423	88,004
Supplemental disclosure of cash flow information:
Interest paid	89	89	780
Income taxes paid	2,247	1,569	2,388
Income tax refunds received	94	164	67
Supplemental disclosure of non-cash investing activities:
Capital expenditures incurred, but not yet paid	411	1,446	305
Property and equipment acquired under capital lease	0	113	40
Business acquisition purchase consideration - assumed equity awards	1,671	0	892
Supplemental disclosure of non-cash financing activities:
Total fair value of restricted stock awards, restricted stock units and performance-based stock awards on date vested	$8,425	$6,816	$1,640

NATURE_OF_THE_BUSINESS

NATURE OF THE BUSINESS	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF THE BUSINESS	NATURE OF THE BUSINESS
	Sonus Networks, Inc. ("Sonus" or the "Company") is a leading provider of networked solutions for communications service providers (e.g., telecommunications, wireless and cable service providers) and enterprises to help them advance, protect and unify their communications and improve collaboration. Sonus helps many of the world's leading communications service providers and enterprises embrace the next generation of Session Initiation Protocol ("SIP") and 4G/LTE (Long Term Evolution)-based solutions, including Voice over Internet Protocol ("VoIP"), video and Unified Communications ("UC") through secure, reliable and scalable Internet Protocol ("IP") networks. Sonus' products include session border controllers ("SBCs"), diameter signaling controllers ("DSCs"), policy/routing servers, media and signaling gateways and network analytics tools.
	Sonus utilizes both direct and indirect sales channels to reach its target customers. Customers and prospective customers in the service provider space are traditional and emerging communications service providers, including long distance carriers, local exchange carriers, Internet service providers, wireless operators, cable operators, international telephone companies and carriers that provide services to other carriers. Enterprise customers and target enterprise customers include financial institutions, retailers, state and local governments, and other multinational corporations.

BASIS_OF_PRESENTATION_AND_SUMM

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	BASIS OF PRESENTATION
	The consolidated financial statements have been prepared in United States dollars, in accordance with accounting principles generally accepted in the United States ("GAAP").
	The Company reports its first, second and third quarters on a 4-4-5 basis, with the quarter ending on the Friday closest to the last day of each third month. In 2014, the Company's first quarter ended on March 28, 2014, the second quarter ended on June 27, 2014 and the third quarter ended on September 26, 2014. In 2013, the Company's first quarter ended on March 29, 2013, the second quarter ended on June 28, 2013 and the third quarter ended on September 27, 2013. In 2012, the Company's first quarter ended on March 30, 2012, the second quarter ended on June 29, 2012 and the third quarter ended on September 28, 2012. The Company's fiscal year ends on December 31.
	In December 2014, the Company's stockholders approved an amendment to Sonus' Fourth Amended and Restated Certificate of Incorporation, as amended, to effect a reverse stock split of its common stock, with the ratio, implementation and timing of such reverse stock split (within specified parameters) to be determined at the discretion of the Company's Board of Directors. In January 2015, the Reverse Stock Split Special Committee of the Board of Directors set the ratio for the reverse stock split at one-for-five and such reverse stock split was made effective on the NASDAQ Global Select Market as of the commencement of trading on January 30, 2015.  As a result of the reverse stock split, the number of the Company's issued and outstanding shares was adjusted such that every five shares of common stock were converted into one share of common stock, reducing the authorized number of shares of the Company's common stock from 600,000,000 to 120,000,000. Proportional adjustments were also made to the Company's equity incentive plans, as well as to any outstanding restricted stock awards and stock options granted under such equity incentive plans to maintain the economic value of the awards.  Following the effective date of the reverse stock split, the par value of the common stock remained at $0.001 per share. Unless otherwise indicated, all references herein to shares outstanding and share issuances have been adjusted to give effect to the aforementioned reverse stock split.
	On February 19, 2014 (the "PT Acquisition Date"), the Company completed the acquisition of Performance Technologies, Incorporated ("PT"). The financial results of PT are included in the Company's consolidated financial statements for the periods subsequent to the PT Acquisition Date.
	On August 24, 2012, the Company completed the acquisition of Network Equipment Technologies, Inc. (“NET”). The financial results of NET have been included in the Company's consolidated financial statements for the periods subsequent to its acquisition.
	SIGNIFICANT ACCOUNTING POLICIES
	Principles of Consolidation
	The accompanying consolidated financial statements include the accounts of Sonus and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
	Use of Estimates and Judgments
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and judgments relied upon in preparing these consolidated financial statements include accounting for business combinations, revenue recognition for multiple element arrangements, inventory valuations, assumptions used to determine the fair value of stock-based compensation, intangible assets and goodwill valuations, legal contingencies and recoverability of Sonus' net deferred tax assets and the related valuation allowances. Sonus regularly assesses these estimates and records changes in estimates in the period in which they become known. Sonus bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances. Actual results could differ from those estimates.
	Business Combinations
	The Company recognizes identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. 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, its 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 that it 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.
	Revenue Recognition
	The Company recognizes revenue from sales when persuasive evidence of an arrangement exists, delivery has occurred, the sale price is fixed or determinable, and collectability of the related receivable is probable. In instances where customer acceptance is required, revenue is deferred until the acceptance has been achieved. When fees for products or services are not fixed and determinable, the Company defers the recording of receivables, deferred revenue and revenue until such time as the fees become due or are collected.
	Revenue from maintenance and support services is recognized ratably over the service period. Maintenance revenue is deferred until the associated product is accepted by the customer and all other revenue recognition criteria have been met. Maintenance and support services include telephone support, return and repair support and unspecified rights to product upgrades and enhancements. Revenue from other professional services is typically recognized as the services are delivered if all other revenue recognition criteria have been met.
	The Company's products typically have both software and non-software components that function together to deliver the products' essential functionality. In addition, hardware sold generally cannot be used apart from the software. Therefore, the Company considers its principal products to be both software and hardware-related. Many of the Company's sales involve multiple element arrangements that include product, maintenance and various professional services.
	Our products typically have both software and non-software components that function together to deliver the products' essential functionality. Many of our sales involve multiple-element arrangements that include both software and hardware-related products, maintenance and various professional services. We recognize revenue in accordance with the provisions of Accounting Standards Codification ("ASC") 605-25, Revenue Recognition - Multiple-Element Arrangements ("ASC 605-25") transactions that include both hardware and software components. We recognize revenue from stand-alone software sales under the software revenue recognition guidance in ASC 985-605, Software - Revenue Recognition ("ASC 985-605"). The Company limits the amount of revenue recognized for delivered elements to the amount that is not contingent on the future delivery of products or services, future performance obligations, or subject to customer-specific return or refund privileges.
	For multiple-element arrangements that include both software-only products and non-software products, the Company allocates the total arrangement consideration to the software-only deliverables as a group and to the individual non-software deliverables based on their relative selling prices. If an undelivered element (such as maintenance and support services) relates to both the software-only and non-software deliverables, the Company bifurcates the consideration allocated to the undelivered element (such as maintenance and support services) into a non-software component and the software-only component using the relative selling price method. The consideration allocated to the non-software and software-only deliverables is recognized in accordance with the guidance as discussed in this note.
	Under ASC 985-605, revenue for any undelivered elements that are considered not essential to the functionality of the product and for which vendor-specific objective evidence of selling price (“VSOE”) has been established is deferred and recognized upon delivery utilizing the residual method. If the Company has undelivered product for which VSOE has not been established, it defers all revenue on the entire arrangement until VSOE is established or until such elements are delivered, provided that all other revenue recognition criteria are met. If the Company has undelivered services for which VSOE has not been established, the entire arrangement is recognized as revenue over the longest remaining service period from the point in time that all services have commenced and all products have been delivered, provided that all other revenue recognition criteria are met.
	For transactions that include multiple elements, arrangement consideration is allocated to each element based on the relative selling prices of all of the elements in the arrangement using the fair value hierarchy as required by ASC 605-25.
	The Company establishes VSOE based upon the price charged when the same element is sold separately or established by management having the relevant pricing authority. The Company has VSOE for its maintenance and support services and certain professional services. When VSOE exists it is used to determine the selling price of a deliverable. The Company has not been able to establish VSOE of any of its products and for certain of its services because the Company has not sold such products or services on a stand-alone basis, has not priced its products or services within a narrow range, or has limited sales history.
	When VSOE is not established, the Company attempts to establish the selling price of each element based on third-party evidence of selling price (“TPE”). The Company's solution typically differs from that of its peers as there are no similar or interchangeable competitor products or services. The Company's various product, service and maintenance offerings contain a significant level of unique features and functionality and therefore, comparable pricing of competitors' products and services with similar functionality cannot be obtained. Accordingly, the Company is not able to determine TPE for its products or services.
	When the Company is unable to establish selling price using VSOE or TPE, the Company uses estimated selling price (“ESP”) in its allocation of arrangement consideration for the relevant deliverables. The objective of ESP is to determine the price at which the Company would transact a sale if a product or service was sold on a stand-alone basis. The Company determines ESP for its products and certain services by considering multiple factors including, but not limited to, overall market conditions, including geographic or regional-specific market factors, profit objectives and historical pricing practices for such deliverables. The determination of ESP is a formal process within the Company that includes review and approval by the Company's management.
	Deferred revenue typically includes customer deposits and amounts associated with partial product shipments and maintenance or service contracts. Deferred revenue expected to be recognized as revenue more than one year subsequent to the balance sheet date is reported as a component of long-term liabilities in the condensed consolidated balance sheets. The Company defers recognition of incremental direct costs, such as cost of goods, third-party installations and commissions, until recognition of the related revenue. Such costs are classified as current assets if the deferred revenue is initially classified as current and noncurrent assets if the related deferred revenue is initially classified as long-term.
	The Company excludes any taxes assessed by a governmental authority that are directly imposed on a revenue-producing transaction (i.e., sales, use, value added) from its revenue and costs. Reimbursement received for out-of-pocket expenses and shipping costs is recorded as revenue.
	The Company sells the majority of its products directly to its end customers. For products sold to resellers and distributors, the Company recognizes revenue on a sell-through basis.
	Financial Instruments
	The carrying amounts of Sonus' financial instruments, which include cash equivalents, investments, accounts receivable, accounts payable and convertible subordinated debt approximate their fair values.
	All investments in marketable securities are classified as available-for-sale and are reported at fair value, with unrealized gains and losses excluded from earnings and reported, net of tax, in Accumulated other comprehensive loss, which is a component of stockholders' equity. Unrealized losses that are determined to be other-than-temporary, based on current and expected market conditions, are recognized in earnings. Declines in fair value determined to be credit-related are charged to earnings. The cost of marketable securities sold is determined by the specific identification method.
	Financial instruments with remaining maturities or that are due within one year from the balance sheet date are classified as current. Financial instruments with remaining maturities or that are payable more than one year from the balance sheet date are classified as noncurrent.
	Cash and Cash Equivalents
	Cash equivalents are stated at fair value, with unrealized gains and losses excluded from earnings and reported, net of tax, in Accumulated other comprehensive income (loss). Cash equivalents are liquid securities that have remaining maturities of three months or less at the date of purchase.
	Restricted Cash
	The Company classifies as restricted cash all cash pledged as collateral to secure long-term obligations and all cash whose use is otherwise limited by contractual provisions. Restricted cash is recorded within other assets on the consolidated balance sheet.
	Foreign Currency Translation
	For foreign subsidiaries where the functional currency is the local currency, assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Revenue and expenses are translated at average rates of exchange prevailing during each period. Translation adjustments for these subsidiaries are included in Accumulated other comprehensive loss.
	For foreign subsidiaries where the functional currency is the U.S. dollar, monetary assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Nonmonetary assets and liabilities are remeasured into U.S. dollars at historical exchange rates. Revenue and expense items are translated at average rates of exchange prevailing during each period.
	Realized and unrealized foreign currency gains and losses arising from transactions denominated in currencies other than the subsidiary's functional currency are reflected in earnings with the exception of intercompany transactions considered to be of a long-term investment nature.
	The components of foreign currency translation gains (losses), which are reported as a component of General and administrative expenses in the consolidated statements of operations, for the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
		Year ended December 31,
		2014			2013			2012
	Transaction losses	$	(420	)	$	(746	)	$	(1,365	)
	Remeasurement gains (losses)	1,980			(164		)	767
		$	1,560		$	(910	)	$	(598	)
	Inventory
	Inventory is recorded at the lower of cost or market value using the first-in, first-out convention. The Company reduces the carrying value of inventory for those items that are potentially excess, obsolete or slow-moving based on changes in customer demand, technology developments or other economic factors.
	Sonus writes down evaluation equipment at the time of shipment to its customers, as it is probable that the inventory value will not be realized.
	Deferred product costs represent deferred cost of revenue for product shipments to customers prior to satisfaction of Sonus' revenue recognition criteria. Such costs are classified as inventory if the related deferred revenue is initially classified as current. Deferred product costs are recorded in Other assets if the related deferred revenue is initially classified as long-term, and remain a component of noncurrent assets until such costs are recognized in the consolidated statement of operations.
	Property and Equipment
	Property and equipment are stated at cost, net of accumulated depreciation. Expenditures for maintenance and repairs are charged to expense as incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, which range from two to five years. Leasehold improvements are amortized over the lesser of the lease term or five years. When an asset is sold or retired, the cost and related accumulated depreciation or amortization are eliminated, and the resulting gain or loss, if any, is recognized in income (loss) from operations in the consolidated statement of operations. The Company reviews property and equipment for impairment in the same manner as intangible assets discussed below.
	Software development costs associated with internal use software are incurred in three stages of development: the preliminary project stage, the application development stage and the post-implementation stage. Costs incurred during the preliminary project and post-implementation stages are expensed as incurred. Certain qualifying costs incurred during the application development stage are capitalized as property and equipment. Internal use software is amortized on a straight-line basis over its estimated useful life of three years, beginning when the software is ready for its intended use.
	Intangible Assets and Goodwill
	Intangible assets are comprised of intellectual property purchased in 2010 which is amortized over its estimated useful life of five years; intangible assets arising from the August 24, 2012 acquisition of NET, comprised of developed technology, customer relationships, order backlog and internal use software, which are amortized over their estimated useful lives of four months to approximately six years; and intangible assets arising from the February 19, 2014 acquisition of PT, comprised of developed technology and customer relationships, which are amortized over their estimated useful lives of six to seven years. Intangible assets are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable based upon the estimated undiscounted cash flows. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by a comparison of the carrying amount of an asset or asset group to future net undiscounted cash flows expected to be generated by the asset or asset group. If these comparisons indicate that an asset is not recoverable, the Company will recognize an impairment loss for the amount by which the carrying value of the asset or asset group exceeds the related estimated fair value. Estimated fair value is based on either discounted future operating cash flows or appraised values, depending on the nature of the asset. In the second quarter of 2013, the Company recorded an impairment charge of $0.6 million to write down the carrying value of one of its intellectual property intangible assets to zero. See Note 9 for additional information regarding this expense.
	Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. Goodwill is not amortized, but instead is tested for impairment at least annually or if indicators of potential impairment exist by comparing the fair value of the Company's reporting unit to its carrying value.
	The Company adopted ASU 2011-08, Intangibles - Goodwill and Other (Topic 350): Testing Goodwill for Impairment ("ASU 2011-08") in fiscal year 2013. ASU 2011-08 permits an entity to first perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. This qualitative assessment included the review of macroeconomic conditions, industry and market considerations, cost factors, overall company financial performance and other related facts and circumstances that could indicate that a more detailed assessment would be required. If it is concluded that it is more likely than not that the fair value is less than the carrying value, then it is necessary to perform the currently prescribed two-step goodwill impairment test. Alternatively, if it is concluded that it is not more likely than not that the fair value exceeds carrying value, the currently prescribed two-step goodwill impairment test is not required.
	The Company's annual testing for impairment of goodwill is completed as of November 30 of each year. The Company operates as a single operating segment with one reporting unit and consequently evaluates goodwill for impairment based on an evaluation of the fair value of the Company as a whole. The Company performed its qualitative assessments for both 2014 and 2013 and concluded each year that it was not more likely than not that the fair value of our reporting unit was less than its carrying value. The Company's testing for 2012 also indicated that no impairment of goodwill existed.
	Other Assets
	Other assets are primarily comprised of the long-term portion of deferred cost of goods sold, prepaid expenses and deposits. In the fourth quarter of 2012, the Company wrote off $7.1 million of prepaid royalties related to products from which the Company does not expect to derive future sales. This amount is included as a component of Cost of revenue - product in the consolidated statement of operations for the year ended December 31, 2012.
	Stock-Based Compensation
	The Company's stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period, and includes an estimate of the awards that will be forfeited. The Company uses the Black-Scholes valuation model for estimating the fair value on the date of grant of stock options. The fair value of stock option awards is affected by the Company's stock price as well as valuation assumptions, including the volatility of Sonus' stock price, expected term of the option, risk-free interest rate and expected dividends.
	Research and Development Costs
	Research and development costs are expensed as incurred.
Software Development Costs
The costs for the development of new software and substantial enhancements to existing software are expensed as incurred until technological feasibility has been established, at which time any additional costs would be capitalized until the product is available for general release. The Company has determined that technological feasibility is established at the time a working model of the software is completed. The Company's process for developing software is essentially completed concurrently with the establishment of technological feasibility. Accordingly, no costs have been capitalized to date.
Concentrations of Credit Risk and Single Source Suppliers
The financial instruments that potentially subject Sonus to concentrations of credit risk are cash, cash equivalents, investments and accounts receivable. The Company's cash equivalents and investments were managed by three financial institutions at December 31, 2014 and two financial institutions at December 31, 2013.
Certain components and software licenses from third parties used in Sonus' products are procured from single sources of supply. The failure of a supplier, including a subcontractor, to deliver on schedule could delay or interrupt Sonus' delivery of products and thereby materially adversely affect Sonus' revenues and operating results.
Sonus had three contract manufacturers at December 31, 2014. Failure to manage the activities of these manufacturers or any disruption in these relationships could result in the disruption in the supply of its products and in delays in the fulfillment of the Company's customer orders.
Advertising Costs
Advertising costs are expensed as incurred. Advertising expenses were $1.5 million for the year ended December 31, 2014, $2.7 million for the year ended December 31, 2013 and $1.1 million for the year ended December 31, 2012.
Operating Segments
The Company operates in a single segment. Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker in making decisions regarding resource allocation and assessing performance. To date, the chief operating decision maker has made such decisions and assessed performance at the company level, as one segment. The Company's chief operating decision maker is its President and Chief Executive Officer.
Loss Contingencies and Reserves
Loss Contingencies. Sonus is subject to ongoing business risks arising in the ordinary course of business that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. Sonus regularly evaluates current information available to determine whether such amounts should be adjusted and records changes in estimates in the period they become known.
Allowance for Doubtful Accounts. Sonus establishes billing terms at the time it negotiates purchase agreements with its customers. Sonus monitors its outstanding receivables for timely payments and potential collection issues. An allowance for doubtful accounts is estimated based on Sonus' assessment of the collectability of specific customer accounts.
Accrual for Royalties. Sonus accrues for royalties for technology that it licenses from vendors based on established royalty rates and usage. In certain cases, Sonus has been contacted by third parties who claim that Sonus' products infringe on certain intellectual property of the third party. Sonus evaluates these claims and accrues amounts only when it is probable that the obligation has been incurred and the amounts are reasonably estimable.
Reserve for Litigation and Legal Fees. Sonus is subject to various legal claims. Sonus reserves for legal contingencies and legal fees when it is probable that a loss has been incurred and the amounts are reasonably estimable.
Accounting for Income Taxes
Deferred tax assets and liabilities are recognized for the expected future consequences of events that have been reflected in the consolidated financial statements. Deferred tax assets and liabilities are determined based on the differences between the book and tax bases of assets and liabilities and operating loss carryforwards, using tax rates expected to be in effect for the years in which the differences are expected to reverse. Such differences arise primarily from stock-based compensation, depreciation, accruals and reserves, acquired intangible assets, deferred revenue, tax credits, net operating loss carryforwards and allowances for accounts receivable. Sonus records valuation allowances to reduce deferred income tax assets to the amount that is more likely than not to be realized.
Sonus has not provided for U.S. income taxes on the undistributed earnings of non-U.S. subsidiaries, as the Company plans to permanently reinvest these amounts. Cumulative undistributed foreign earnings were approximately $28 million at December 31, 2014 and approximately $17 million at December 31, 2013. Generally, the undistributed foreign earnings become subject to U.S. taxation upon the remittance of dividends and under certain other circumstances. The Company has been taxed on certain earnings of its non-U.S. subsidiaries. Previously taxed earnings were approximately $15 million at December 31, 2014 and $11 million at December 31, 2013. Thus, $13 million of the undistributed earnings at December 31, 2014 and $6 million at December 31, 2013 are subject to U.S. income taxes on undistributed earnings. The Company does not believe it is practicable to estimate with reasonable accuracy the hypothetical amount of the unrecognized deferred tax liability on its undistributed foreign earnings given the large number of tax jurisdictions involved and the many factors and assumptions required to estimate the amount of the U.S. federal income tax on the undistributed earnings after reduction for the available foreign tax credits.
The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, no amount of the benefit attributable to the position is recognized. The tax benefit to be recognized of any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes.
In September 2013, the U.S. Department of the Treasury and the Internal Revenue Service released final regulations relating to guidance on applying tax rules to amounts paid to acquire, produce or improve tangible personal property as well as rules for materials and supplies effective for tax years beginning on or after January 1, 2014. The Company has reviewed the regulations and has determined that its current method of accounting is appropriate under the regulations with no change required.
Recent Accounting Pronouncements
In August 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern ("ASU 2014-15"). ASU 2014-15 provides guidelines determining when and how to disclose going concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity's ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity's ability to continue as a going concern. AS 2014-15 applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. The adoption of ASU 2014-15 is not expected to have a material impact on the Company's consolidated financial statements.
In June 2014, the FASB issued ASU 2014-12, Compensation - Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period (a consensus of the FASB Emerging Issues Task Force) (“ASU 2014-12”). ASU 2014-12 clarifies that entities should treat performance targets that can be met after the requisite service period of a share-based payment award as performance conditions that affect vesting. Therefore, an entity would not record compensation expense (measured as of the grant date without taking into account the effect of the performance target) related to an award for which transfer to the employee is contingent upon the entity’s satisfaction of a performance target until it becomes probable that the performance target will be met. ASU 2014-12 does not contain any new disclosure requirements. ASU 2014-12 is effective for the Company on January 1, 2015. The Company does not expect the adoption of ASU 2014-12 to have a material impact on its consolidated financial statements.
In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”) its final standard on revenue from contracts with customers. ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that an entity recognizes 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. In applying the revenue model to contracts within its scope, an entity identifies the contract(s) with a customer, identifies the performance obligations in the contract, determines the transaction price, allocates the transaction price to the performance obligations in the contract and recognizes revenue when (or as) the entity satisfies a performance obligation. ASU 2014-09 applies to all contracts with customers that are within the scope of other topics in the FASB Accounting Standards Codification ("ASC"). Certain of ASU 2014-09’s provisions also apply to transfers of nonfinancial assets, including in-substance nonfinancial assets that are not an output of an entity’s ordinary activities (i.e., property plant and equipment; real estate; or intangible assets). Existing accounting guidance applicable to these transfers has been amended or superseded. ASU 2014-09 also requires significantly expanded disclosures about revenue recognition. ASU 2014-09 is effective for the Company on January 1, 2017. The Company is currently assessing the potential impact of the adoption of ASU 2014-09 on its condensed consolidated financial statements.
In April 2014, the FASB issued ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (“ASU 2014-08”), which amends the definition of discontinued operations in ASC 205-20 and requires entities to provide additional disclosures about discontinued operations as well as disposal transactions that do not meet the discontinued operations criteria. The new guidance eliminates the previous criteria that the operations and cash flows of the component that have been (or will be) eliminated from the ongoing operations of the entity as a result of the disposal transaction. The new guidance also eliminates the previous criteria that the entity will not have any significant continuing involvement in the operations of the component after the disposal transaction. Instead, ASU 2014-08 requires discontinued operations treatment for disposals of a component or group of components that represents a strategic shift that has or will have a major impact on an entity’s operations or financial results. ASU 2014-08 requires entities to reclassify assets and liabilities of a discontinued operation for all comparative periods presented in the statement of financial position. In addition, ASU 2014-08 requires that an entity disclose in its statement of cash flows, for all periods presented, either: (1) operating and investing cash flows or (2) depreciation and amortization, capital expenditures and significant operating and investing non-cash items related to the discontinued operation. ASU 2014-08 is effective prospectively for all disposals (except disposals classified as held for sale before the adoption date) or components initially classified as held for sale in periods beginning on or after December 15, 2014. The Company does not expect the adoption of ASU 2014-08 to have a material impact on its consolidated financial statements.
In July 2013, the FASB issued ASU 2013-11, Presentation of a Liability for an Unrecognized Tax Benefit When a Net Operating Loss Carryforward or Tax Credit Carryforward Exists ("ASU 2013-11"), which provides guidance on financial statement presentation of an unrecognized tax benefit when a net operating loss ("NOL") carryforward, a similar tax loss or a tax credit carryforward exists. The FASB's objective in issuing ASU 2013-11 was to eliminate diversity in practice resulting from a lack of guidance on this topic in current GAAP. ASU 2013-11 requires that an entity present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, in the financial statements as a reduction to a deferred tax asset for an NOL carryforward, a similar tax loss or a tax credit unless certain conditions exist. ASU 2013-11 was effective for the Company beginning January 1, 2014. The adoption of ASU 2013-11 did not have an impact on the Company's consolidated financial statements, as the Company already applied the methodology prescribed by ASU 2013-11.
In March 2013, the FASB issued ASU 2013-05, Foreign Currency Matters (Topic 830) - Parent's Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity ("ASU 2013-05"), which indicates that the entire amount of a cumulative translation adjustment ("CTA") related to an entity's investment in a foreign entity should be released when there has been either: (a) a sale of a subsidiary or group of net assets within a foreign entity and the sale represents the substantially complete liquidation of the investment in a foreign entity; (b) the loss of a controlling financial interest in an investment in a foreign entity (i.e., the foreign entity is deconsolidated); or (c) the step acquisition of a foreign entity (i.e., when the accounting for an entity has changed from applying the equity method for an investment in a foreign entity to consolidating the foreign entity). ASU 2013-05 does not change the requirement to release a pro rata portion of the CTA of the foreign entity into earnings for a partial sale of an equity method investment in a foreign entity. ASU 2013-05 was effective for the Company beginning January 1, 2014. The adoption of ASU 2013-05 did not have a material impact on the Company's consolidated financial statements.

BUSINESS_ACQUISITONS

BUSINESS ACQUISITONS	12 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Business Acquisitions	BUSINESS ACQUISITIONS
	Performance Technologies, Incorporated
	On the PT Acquisition Date, the Company acquired all of the outstanding common stock of PT for cash consideration of $35.0 million, or $3.75 per share of PT common stock. This acquisition has enabled Sonus to expand its solutions portfolio with signaling technology and acquire expertise to enable mobile service providers to offer new real-time multimedia services through their mobile infrastructure. Delivering these services across the LTE next-generation mobile networks will require adoption of the next-generation signaling technology known in the industry as Diameter Signal. The acquisition of PT has allowed Sonus to diversify its product portfolio with an integrated, virtualized Diameter and SIP-based solution and deliver strategic value to service providers seeking to offer new multimedia services through mobile, cloud-based, real-time communications.
	The transaction has been accounted for as a business combination and the financial results of PT have been included in the Company's consolidated financial statements starting on the PT Acquisition Date.
	The Company finalized the valuation of acquired assets, identifiable intangible assets, uncertain tax liabilities and certain accrued liabilities in the fourth quarter of 2014. Based on new information gathered about facts and circumstances that existed as of the PT Acquisition Date related to the valuation of certain acquired assets and assumed liabilities, the Company recorded adjustments which resulted in an increase to goodwill of $0.6 million, a decrease to other current assets of $0.4 million and an increase to other long-term liabilities of $0.2 million in the period subsequent to the PT Acquisition Date. The Company recorded $8.8 million of goodwill, primarily due to expected synergies between the combined companies and expanded market opportunities. The goodwill is not deductible for tax purposes.
	A summary of the allocation of the purchase consideration for PT is as follows (in thousands):
	Fair value of consideration transferred:
	Cash, net of cash acquired	$	35,022
	Fair value of equity awards assumed (see Note 16)	1,671
	Fair value of total consideration	$	36,693
	Fair value of assets acquired and liabilities assumed:
	Marketable securities	$	2,315
	Other current assets	9,337
	Property and equipment	2,251
	Intangible assets	17,100
	Goodwill	8,781
	Current liabilities	(2,762		)
	Other long-term liabilities	(329		)
		$	36,693
	The valuation of the acquired intangible assets is inherently subjective and relies on significant unobservable inputs. The Company used an income approach to value the acquired developed technology and customer relationships intangible assets. The valuation for each of these intangible assets was based on estimated projections of expected cash flows to be generated by the assets, discounted to the present value at discount rates commensurate with perceived risk. The valuation assumptions take into consideration the Company's estimates of contract renewal, technology attrition and revenue growth projections. The Company is amortizing the identifiable intangible assets in relation to the expected cash flows from the individual intangible assets over their respective useful lives. These intangible assets have a weighted average useful life of 6.8 years (see Note 9).
	The identifiable intangible assets recorded in connection with the PT acquisition are as follows (in thousands):
	Developed technology	$	13,200
	Customer relationships	3,900
		$	17,100
	The Company recognized revenue aggregating $14.6 million in the period from the PT Acquisition Date through December 31, 2014. The Company has not disclosed the amount of earnings of PT since the PT Acquisition Date or pro forma financial information, as these amounts are not significant to the Company's consolidated financial statements.
	Sale of Multi-Protocol Server Business
	On June 20, 2014 (the "MPS Sale Date"), the Company sold its PT Multi-Protocol Server ("MPS") business for $2.0 million, comprised of $0.2 million of inventory, $0.1 million of fixed assets, $0.2 million of deferred revenue and $1.9 million of PT goodwill allocable to the MPS business. The Company had acquired the MPS business in connection with the acquisition of PT. The Company incurred $0.4 million of transaction costs, which are included as a component of General and administrative expenses. The results of operations of the MPS business are excluded from the Company's consolidated results for the period subsequent to the MPS Sale Date.
	Network Equipment Technologies, Inc.
	On August 24, 2012 (the “NET Acquisition Date”), the Company acquired all of the outstanding common stock of NET for cash consideration of $41.5 million, or $1.35 per share of NET common stock. The acquisition was effected through a merger of a wholly-owned subsidiary of the Company into NET with NET surviving the merger as a wholly-owned subsidiary of the Company. NET is a provider of networking equipment focused on secure real-time communications for UC, SIP trunking, enterprise mobility and IP-based multi-service networking. The Company acquired NET to enhance its position as an enabler of cloud-based UC. The acquisition of NET expanded the Company's portfolio of Session Border Controller (“SBC”) solutions for enterprise customers and brought engineering resources, broader channel capability and a broad U.S. federal government installed base to leverage into SIP-enabled platforms.
	The transaction has been accounted for as a business combination, and the financial results of NET have been included in the Company's consolidated financial statements for the period subsequent to its acquisition. The Company's financial results for year ended December 31, 2012 include $17.3 million of revenue and $9.5 million of net loss attributable to NET for the period subsequent to its acquisition.
	The Company finalized the valuation of acquired assets, identifiable intangible assets, uncertain tax liabilities and certain accrued liabilities in the third quarter of 2013. Based on new information gathered about facts and circumstances that existed as of the NET Acquisition Date, the Company recorded retrospective adjustments as of December 31, 2012, which resulted in a net decrease to goodwill of $1.4 million, a net increase to other current assets of $0.9 million and a net decrease to current liabilities of $0.5 million as set forth in the table below. The adjustments have been retrospectively applied to the December 31, 2012 balance sheet; however, these adjustments had no impact on the consolidated statements of operations, of comprehensive loss, of stockholders' equity or of cash flows.
	During the second quarter of 2013, the Company made an election under Section 338(g) of the Internal Revenue Code to have the NET transaction treated as an asset acquisition (i.e., a taxable transaction) with the goodwill being deductible for tax purposes over 15 years.
	A summary of the allocation of the purchase consideration for NET is as follows (in thousands):
	Fair value of consideration transferred:
	Cash, net of cash acquired	$	35,508
	Fair value of equity awards assumed (see Note 16)	892
	Fair value of total consideration	$	36,400
	Fair value of assets acquired and liabilities assumed:
	Marketable securities	$	5,359
	Deferred income taxes	681
	Other current assets	13,388
	Property and equipment	4,694
	Noncurrent investments	10,167
	Intangible assets	16,810
	Goodwill	27,317
	Other noncurrent assets	1,843
	Current liabilities	(9,350		)
	Debt	(34,208		)
	Other long-term liabilities	(301		)
		$	36,400
	The valuation of the acquired intangible assets is inherently subjective and relies on significant unobservable inputs. The Company used an income approach to value the acquired customer relationships and developed technology intangible assets. The valuation for each of these intangible assets was based on estimated projections of expected cash flows to be generated by the assets, discounted to the present value at discount rates commensurate with perceived risk. The valuation assumptions take into consideration the Company's estimates of contract renewal, technology attrition and revenue growth projections. The Company is amortizing the identifiable intangible assets in relation to the expected cash flows from the individual intangible assets over their respective useful lives (see Note 9).
	The identifiable intangible assets recorded in connection with the NET acquisition are as follows (in thousands):
	Developed technology	$	9,080
	Customer relationships	6,140
	Order backlog	860
	Internal use software	730
		$	16,810
	Pro Forma Results
	The following unaudited pro forma information presents the condensed combined results of operations of the Company and NET for the year ended December 31, 2012 as if the acquisition of NET had been completed on January 1, 2011 with adjustments to give effect to pro forma events that are directly attributable to the acquisition. These pro forma adjustments include a reduction of historical NET revenue for the fair value adjustment related to acquired deferred revenue, an increase in amortization expense for the acquired identifiable intangible assets, a decrease in historical NET interest expense reflecting the extinguishment of certain of NET's debt as a result of the acquisition and the elimination of transaction costs included in the Company's and NET's historical results, directly attributable to the acquisition from the year ended December 31, 2012.
	The unaudited pro forma results do not reflect any operating efficiencies or potential cost savings which may result from the consolidation of the operations of the Company and NET. Accordingly, these unaudited pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the combined company that would have been achieved had the acquisition occurred at the beginning of the period presented, nor are they intended to represent or be indicative of future results of operations (in thousands, except per share amounts):
		Year ended
		December 31,
		2012
	Revenue	$	284,970
Net loss	$	(62,148	)
Loss per share	$	(1.11	)
Acquisition-Related Expenses
Acquisition-related expenses include those expenses related to the acquisition that would otherwise not have been incurred by the Company. These expenses include professional and services fees, such as legal, audit, consulting, paying agent and other fees, and expenses related to cash payments to certain former executives of the acquired businesses under their respective change of control agreements. Of the amounts recorded in the year ended December 31, 2014, $1.3 million relates to the acquisition of PT and $0.3 million relates to professional fees in connection with the January 2, 2015 transaction with Treq Labs, Inc. (see Note 22). The amount recorded in the year ended December 31, 2013 relates to the acquisition of PT and the amount recorded in the year ended December 31, 2012 relates to the acquisition of NET.
The components of acquisition-related costs incurred in the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
	Year ended December 31,
	2014			2013		2012
Professional and services fees	$	1,309		$	93	$	3,571
Change of control agreements	249			—		1,925
	$	1,558		$	93	$	5,496

EARNINGS_LOSS_PER_SHARE

EARNINGS (LOSS) PER SHARE	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
EARNINGS (LOSS) PER SHARE	EARNINGS (LOSS) PER SHARE
	Basic earnings (loss) per share is computed by dividing net income (loss) by the weighted average number of shares outstanding during the period. For periods in which the Company reports net income, diluted net income per share is determined by using the weighted average number of common and dilutive common equivalent shares outstanding during the period unless the effect is antidilutive.
	The calculations of shares used to compute basic and diluted loss per share are as follows (in thousands):
		Year ended December 31,
		2014	2013	2012
	Weighted average shares outstanding—basic	50,245	55,686	56,018
	Potential dilutive common shares	—	—	—
	Weighted average shares outstanding—diluted	50,245	55,686	56,018
	Options to purchase the Company's common stock, unvested shares of restricted stock, unvested performance-based stock awards for which the performance conditions have been satisfied and shares in connection with future purchases under the Company's Amended and Restated 2000 Employee Stock Purchase Plan, as amended (the "ESPP") aggregating 8.0 million shares for the year ended December 31, 2014 have not been included in the computation of diluted loss per share because their effect would have been antidilutive. Options to purchase the Company's common stock, unvested shares of restricted stock and unvested performance-based stock awards for which the performance conditions have been satisfied aggregating 7.1 million shares for the year ended December 31, 2013 and 5.6 million shares for the year ended December 31, 2012 have not been included in the computation of diluted loss per share because their effect would have been antidilutive.

CASH_EQUIVALENTS_AND_INVESTMEN

CASH EQUIVALENTS AND INVESTMENTS	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS	CASH EQUIVALENTS AND INVESTMENTS
	The Company invests in debt and equity instruments, primarily U.S. government-backed, municipal and corporate obligations, which management believes to be high quality (investment grade) credit instruments.
	During the year ended December 31, 2014, the Company sold $45.9 million of its available-for-sale securities and realized gross gains aggregating $46,000, which are included as a component of Other income, net, in the Company's consolidated statement of operations for that period. The Company did not realize any gross losses on these sales. The Company did not sell any of its available-for-sale securities during the years ended December 31, 2013 or 2012, and accordingly, no gains or losses were realized.
	Investments with continuous unrealized losses for one year or greater at December 31, 2014 were nominal; however, since the Company does not intend to sell these securities and does not believe it will be required to sell any securities before they recover in value, it does not believe these declines are other-than-temporary.
	On a quarterly basis, the Company reviews its investments to determine if there have been any events that could create a credit impairment. Based on its reviews, the Company does not believe that any impairment existed with its current holdings at December 31, 2014.
	The amortized cost, gross unrealized gains and losses and fair value of the Company's cash equivalents and investments at December 31, 2014 and 2013 were comprised of the following (in thousands):
		31-Dec-14
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	11,653	$	—	$	—		$	11,653
	Short-term investments
	Municipal obligations	$	1,273	$	1	$	(1	)	$	1,273
	U.S. government agency notes	4,016		—		—			4,016
	Corporate debt securities	40,921		2		(59		)	40,864
	Commercial paper	9,340		—		—			9,340
	Certificates of deposit	8,950		—		—			8,950
		$	64,500	$	3	$	(60	)	$	64,443
	Investments
	Municipal obligations	$	2,702	$	1	$	(3	)	$	2,700
	U.S. government agency notes	2,300		—		(1		)	2,299
	Corporate debt securities	35,897		4		(86		)	35,815
	Commercial paper	1,093		—		—			1,093
	Certificates of deposit	500		—		—			500
		$	42,492	$	5	$	(90	)	$	42,407
		31-Dec-13
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	50,404	$	—	$	—		$	50,404
	Short-term investments
	U.S. government agency notes	$	47,895	$	15	$	—		$	47,910
	Corporate debt securities	81,993		35		(8		)	82,020
	Commercial paper	5,647		2		—			5,649
	Certificates of deposit	3,300		3		—			3,303
		$	138,835	$	55	$	(8	)	$	138,882
	Investments
	U.S. government agency notes	$	9,254	$	3	$	—		$	9,257
	Foreign government notes	1,250		—		—			1,250
	Corporate debt securities	23,848		17		(8		)	23,857
		$	34,352	$	20	$	(8	)	$	34,364
	The Company's available-for-sale debt securities that are classified as Investments in the consolidated balance sheet mature after one year but within two years or less from the balance sheet date.
	Fair Value Hierarchy
	Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The three-tier fair value hierarchy is based on the level of independent, objective evidence surrounding the inputs used to measure fair value. A financial instrument's categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The fair value hierarchy is as follows:
	Level 1. Level 1 applies to assets or liabilities for which there are quoted prices in active markets for identical assets or liabilities.
	Level 2. Level 2 applies to assets or liabilities for which there are inputs that are directly or indirectly observable in the marketplace, such as quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in markets with insufficient volume or infrequent transactions (less active markets).
	Level 3. Level 3 applies to assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of the assets or liabilities.
	The following table shows the fair value of the Company's financial assets at December 31, 2014 and 2013. These financial assets are comprised of the Company's available-for-sale debt securities and reported under the captions Cash and cash equivalents, Short-term investments and Investments in the consolidated balance sheets (in thousands):
				Fair value measurements at
				December 31, 2014 using:
		Total carrying		Quoted prices		Significant other			Significant
		value at		in active		observable			unobservable
		December 31,		markets		inputs			inputs
		2014		(Level 1)		(Level 2)			(Level 3)
	Cash equivalents	$	11,653	$	11,653	$	—		$	—
	Short-term investments
	Municipal obligations	$	1,273	$	—	$	1,273		$	—
	U.S. government agency notes	4,016		—		4,016			—
	Corporate debt securities	40,864		—		40,864			—
	Commercial paper	9,340		—		9,340			—
	Certificates of deposit	8,950		—		8,950			—
		$	64,443	$	—	$	64,443		$	—
	Investments
	Municipal obligations	$	2,700	$	—	$	2,700		$	—
	U.S. government agency notes	2,299		—		2,299			—
	Corporate debt securities	35,815		—		35,815			—
Commercial paper	1,093		—		1,093			—
Certificates of deposit	500		—		500			—
	$	42,407	$	—	$	42,407		$	—
			Fair value measurements at
			December 31, 2013 using:
	Total carrying		Quoted prices		Significant other			Significant
	value at		in active		observable			unobservable
	December 31,		markets		inputs			inputs
	2013		(Level 1)		(Level 2)			(Level 3)
Cash equivalents	$	50,404	$	50,404	$	—		$	—
Short-term investments
U.S. government agency notes	$	47,910	$	—	$	47,910		$	—
Corporate debt securities	82,020		—		82,020			—
Commercial paper	5,649		—		5,649			—
Certificates of deposit	3,303		—		3,303			—
	$	138,882	$	—	$	138,882		$	—
Investments
U.S. government agency notes	$	9,257	$	—	$	9,257		$	—
Foreign government notes	1,250		—		1,250			—
Corporate debt securities	23,857		—		23,857			—
	$	34,364	$	—	$	34,364		$	—
The Company's marketable securities and investments have been valued with the assistance of valuations provided by third-party pricing services, as derived from such services' pricing models. Inputs to the models may include, but are not limited to, reported trades, executable bid and asked prices, broker/dealer quotations, prices or yields of securities with similar characteristics, benchmark curves or information pertaining to the issuer, as well as industry and economic events. The pricing services may use a matrix approach, which considers information regarding securities with similar characteristics to determine the valuation for a security. The Company is ultimately responsible for the consolidated financial statements and underlying estimates. Accordingly, the Company assesses the reasonableness of the valuations provided by the third-party pricing services by reviewing actual trade data, broker/dealer quotes and other similar data, which are obtained from quoted market prices or other sources.

ACCOUNTS_RECEIVABLE_NET

ACCOUNTS RECEIVABLE, NET	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
ACCOUNTS RECEIVABLE, NET	ACCOUNTS RECEIVABLE, NET
	Accounts receivable, net, consist of the following (in thousands):
		December 31,
		2014			2013
	Accounts receivable, gross	$	63,001		$	64,620
	Allowance for doubtful accounts	(58		)	(157		)
	Accounts receivable, net	$	62,943		$	64,463
	The activity in the Company's allowance for doubtful accounts is as follows (in thousands):
	Year ended December 31,	Balance at			Charges			Write-offs			Balance at
		beginning			to expense						end of
		of year									year
	2014	$	157		$	92		$	(191	)	$	58
	2013	$	—		$	415		$	(258	)	$	157
	2012	$	—		$	—		$	—		$	—

INVENTORY

INVENTORY	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
INVENTORY	INVENTORY
	Inventory consists of the following (in thousands):
		December 31,
		2014			2013
	On-hand final assemblies and finished goods inventories	$	19,285		$	19,070
	Deferred cost of goods sold	2,829			4,387
		22,114			23,457
	Less current portion	(22,114		)	(21,793		)
	Noncurrent portion (included in Other assets)	$	—		$	1,664

PROPERTY_AND_EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT
	Property and equipment consists of the following (in thousands):
				December 31,
		Useful Life		2014				2013
	Equipment	3 years		$	65,703			$	80,710
	Software	2-3 years		17,342				15,410
	Furniture and fixtures	3-5 years		612				855
	Leasehold improvements	Shorter of the life of the lease or estimated useful life (1-5 years)		11,920				10,659
				95,577				107,634
	Less accumulated depreciation and amortization			(77,732		)		(88,532		)
	Property and equipment, net			$	17,845			$	19,102
	The Company recorded depreciation and amortization expense related to property and equipment of $11.5 million for the year ended December 31, 2014, $12.3 million for the year ended December 31, 2013 and $12.9 million for the year ended December 31, 2012. During the year ended December 31, 2014, the Company disposed of certain property and equipment that was fully depreciated at the time of disposal, which resulted in reductions in both Cost and Accumulated depreciation.
	Property and equipment under capital leases included in the amounts above are as follows (in thousands):
		December 31,
		2014				2013
	Cost	$	113			$	326
	Less accumulated depreciation	(71		)		(220		)
	Property and equipment under capital leases, net	$	42			$	106
	The net book values of the Company's property and equipment by geographic area are as follows (in thousands):
		December 31,
		2014				2013
	United States	$	12,652			$	13,960
	Asia/Pacific	3,574				4,665
	Europe	765				453
	Other	854				24
		$	17,845			$	19,102

INTANGIBLE_ASSETS_AND_GOODWILL

INTANGIBLE ASSETS AND GOODWILL	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS AND GOODWILL	INTANGIBLE ASSETS AND GOODWILL
	The Company's intangible assets at December 31, 2014 and 2013 consist of the following (in thousands):
	31-Dec-14	Weighted average amortization period		Cost				Accumulated				Net
		(years)						amortization				carrying value
	Intellectual property	5		$	999			$	999			$	—
	Developed technology	6.18		22,280				5,193				17,087
	Customer relationships	5.57		10,040				4,695				5,345
	Internal use software	3		730				568				162
		5.75		$	34,049			$	11,455			$	22,594
	31-Dec-13	Weighted average amortization period		Cost				Accumulated				Net
		(years)						amortization				carrying value
	Intellectual property	5		$	999			$	999			$	—
	Developed technology	5.03		9,080				2,729				6,351
	Customer relationships	5.3		6,140				2,806				3,334
	Internal use software	3		730				324				406
		4.35		$	16,949			$	6,858			$	10,091
	Amortization expense for intangible assets for the years ended December 31, 2014, 2013 and 2012 was as follows (in thousands):
		Year ended December 31,												Statement of operations classification
		2014				2013				2012
	Intellectual property	$	—			$	200			$	400			Research and development
	Developed technology	2,464				1,999				730				Cost of revenue - product
	Customer relationships	1,889				2,104				702				Sales and marketing
	Order backlog	—				—				860				Cost of revenue - product
	Internal use software	244				243				81				Cost of revenue - product
		$	4,597			$	4,546			$	2,773
	In connection with the preparation of its financial statements for the second quarter of 2013, the Company reviewed its intangible assets and other long-lived assets for impairment indicators. The Company determined that a triggering event had occurred relative to one of its intellectual property intangible assets that had been acquired during 2010. During 2013, the Company discontinued its development of this technology and determined that there were no alternative uses of the technology within either its existing or future product lines. Additionally, based on the age and resulting obsolescence of such technology, the Company concluded that the fair value was nominal based on a discounted cash flow model. As a result, the Company recorded an impairment charge of $0.6 million to write down the carrying value of the asset to zero. This expense is included as a component of research and development expense in the Company's consolidated statements of operations for the year ended December 31, 2013. The nonrecurring fair value measurement of the impairment of the intellectual property was categorized in Level 3 of the fair value hierarchy.
	Estimated future amortization expense for the Company's intangible assets at December 31, 2014 is as follows (in thousands):
	Years ending December 31,
	2015	$	5,646
	2016	5,290
	2017	5,259
	2018	2,953
	2019	2,263
	Thereafter	1,183
		$	22,594
	Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. The changes in the carrying value of the Company's goodwill in the years ended December 31, 2014 and 2013 are as follows (in thousands):
		Year ended December 31,
		2014				2013
	Balance at January 1
	Goodwill	$	35,485			$	35,485
	Accumulated impairment losses	(3,106		)		(3,106		)
		32,379				32,379
	Acquisition of PT	8,781				—
	Sale of MPS business	(1,897		)		—
	Balance at December 31	$	39,263			$	32,379
	The components of the Company's goodwill balances at December 31, 2014 and 2013 are as follows:
		December 31,
		2014				2013
	Balance
	Goodwill	$	42,369			$	35,485
	Accumulated impairment losses	(3,106		)		(3,106		)
		$	39,263			$	32,379

ACCRUED_EXPENSES

ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES
	Accrued expenses consist of the following (in thousands):
		December 31,
		2014		2013
	Employee compensation and related costs	$	20,042	$	20,683
	Other	12,107		13,343
		$	32,149	$	34,026

RESTRUCTURING_ACCRUAL

RESTRUCTURING ACCRUAL	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
RESTRUCTURING ACCRUAL	RESTRUCTURING ACCRUAL
	The Company is committed to streamlining operations and reducing operating costs by closing and consolidating certain facilities and reducing its worldwide workforce. The Company recorded $5.6 million of restructuring expense in the year ended December 31, 2014, comprised of $3.6 million for severance and related costs, $1.8 million related to the early termination of leases on three facilities and $0.2 million for the write-off of assets associated with these facilities. Of this amount, $2.3 million was recorded in connection with the PT acquisition, comprised of $1.7 million for severance and related costs, $0.5 million related to PT's former corporate headquarters in New York and $0.1 million for the write-off of assets in connection with the PT facility.
	The Company recorded $5.4 million of restructuring expense in the year ended December 31, 2013, comprised of $5.1 million for severance and related costs in connection with reducing the Company's workforce and $0.3 million related to facilities.
	The Company recorded $7.7 million of restructuring expense in the year ended December 31, 2012, comprised of $3.2 million for severance and related costs, $4.2 million related to space reductions in three facilities and $0.3 million for the write-off of assets associated with the aforementioned facility consolidations. The $4.2 million recorded in the year ended December 31, 2012 related to facilities is principally comprised of $4.0 million related to space reductions in NET's former corporate headquarters in California.
	Restructuring expense is reported separately in the Company's consolidated statements of operations. The Company expects to complete the payments related to severance in 2015 and the payments related to facilities in 2019.
	The portion of restructuring payments due more than one year from the balance sheet date is included in Other long-term liabilities in the Company's consolidated balance sheets. At December 31, 2014, the long-term portion of accrued restructuring was $1.9 million and represents future lease payments on restructured facilities.
	The tables below summarize the restructuring accrual activity for the years ended December 31, 2014 and 2013 (in thousands):
		Balance at		Initiatives		Cash			Balance at
		January 1,		charged to		payments			December 31,
		2014		expense					2014
	Severance	$	1,333	$	3,615	$	(3,266	)	$	1,682
	Facilities	3,012		1,820		(1,180		)	3,652
		$	4,345	5,435		$	(4,446	)	$	5,334
	Asset write-offs			190
				$	5,625
		Balance at		Initiatives		Cash			Balance at
		January 1,		charged to		payments			December 31,
		2013		expense					2013
	Severance	$	1,135	$	5,102	$	(4,904	)	$	1,333
	Facilities	4,100		309		(1,397		)	3,012
		$	5,235	$	5,411	$	(6,301	)	$	4,345

DEBT

DEBT	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
DEBT	DEBT
	Credit Agreement
	On June 27, 2014, the Company entered into a credit agreement (the "Credit Agreement") by and among the Company, as Borrower, Bank of America, N.A. ("Bank of America"), as Administrative Agent, Swing Line Lender and L/C Issuer, and the other lenders from time to time party thereto. The Credit Agreement provides for a revolving credit facility of up to $40 million and provides that the Company may select the interest rates under the credit facility equal to (1) the Eurodollar Rate (which is defined as the rate per annum equal to the London Interbank Offered Rate plus 1.5% per annum) for a Eurodollar Rate Loan; and (2) the highest of (a) the Federal Funds Rate plus 1/2 of 1%, (b) the rate of interest in effect on the borrowing date as publicly announced from time to time by Bank of America as its prime rate, and (c) the monthly Eurodollar Rate plus 1%. The Company will pay a 0.15% commitment fee on the unused commitments available for borrowing.
	Borrowings under the Credit Agreement may be used for the general corporate purposes of the Company and its subsidiaries, including working capital, acquisitions, dividends and stock repurchases, to the extent permitted under the Credit Agreement.
	The obligations of the Company under the Credit Agreement are guaranteed by Sonus International, Inc., Sonus Federal, Inc., NET and PT (collectively, together with the Company, the "Loan Parties") pursuant to a Master Continuing Guaranty and are secured by the assets of the Loan Parties pursuant to a Security and Pledge Agreement.
	The Credit Agreement contains affirmative, negative and financial covenants customary for financings of this type. The negative covenants include limitations on liens, indebtedness, fundamental changes, dispositions, restricted payments, investments, transactions with affiliates, certain restrictive agreements and compliance with sanctions laws and regulations. The amount of cash and cash equivalents of the Loan Parties, subject to certain exclusions, cannot be less than an aggregate amount of $100 million at any time. The credit facility will become due on June 27, 2015, subject to acceleration upon certain specified events of default, including, without limitation, payment defaults, defaults in the performance of affirmative and negative covenants, the inaccuracy of representations or warranties, bankruptcy and insolvency-related defaults, defaults relating to judgments, an ERISA Event (as defined in the Credit Agreement), the failure to pay specified indebtedness and a change of control default.
	The Company did not have any amounts outstanding under the Credit Agreement at December 31, 2014.
	Assumed Debt - NET Acquisition
	2007 Notes
	In December 2007, NET issued $85.0 million of 3 3/4% Convertible Senior Notes due December 15, 2014 (the "2007 Notes") in a private placement, of which $10.5 million in principal remained outstanding at the NET Acquisition Date, and under which NET remained obligated after the acquisition. The 2007 Notes bore interest at a rate of 3 3/4 % per annum and matured on December 15, 2014. The 2007 Notes were unsecured senior obligations of NET, ranking equal in right of payment to all existing and future senior indebtedness of NET, and senior in right of payment to any existing and future subordinated indebtedness of NET.
	On August 24, 2012, in connection with the consummation of the acquisition and as provided in the merger agreement, NET entered into a supplemental indenture for the 2007 Notes, which provided, among other things, that, in lieu of being convertible into shares of NET common stock, the 2007 Notes will be convertible into the kind and amount of merger consideration that would have been receivable upon the consummation of the acquisition by a holder of the number of shares of NET common stock issuable upon conversion of such 2007 Notes immediately preceding the effective time of the acquisition. The merger consideration was $1.35 in cash per share of NET common stock.
	The acquisition of NET by the Company constituted a "fundamental change" under the indenture governing the 2007 Notes, which triggered the distribution of a fundamental change notice to each holder of 2007 Notes, indicating that each such holder had the right to have all or a portion of its 2007 Notes purchased at a price in cash equal to 100% of the principal amount of the 2007 Notes (or portion thereof), plus any accrued and unpaid interest to, but excluding the fundamental change purchase date of October 12, 2012. In response to the fundamental change notice, $8.1 million in aggregate principal amount of 2007 Notes were tendered for purchase. The remaining $2.4 million in aggregate principal amount was paid in full on December 4, 2014 and accordingly, at December 31, 2014, NET's obligations under the 2007 Notes were discharged.
	The Company determined that the estimated fair value of its outstanding debt at December 31, 2013 equaled its carrying value. Although the debt could have been publicly traded, there were no trading transactions since 2010 and accordingly, the Company categorized it as a Level 2 within the fair value hierarchy.
	1989 Debentures
	In May 1989, NET issued $75.0 million of 7 1/4% Redeemable Convertible Subordinated Debentures due May 15, 2014 (the "1989 Debentures"), of which $23.7 million in aggregate principal amount remained outstanding as of the NET Acquisition Date, and under which NET remained obligated after the acquisition. The 1989 Debentures bore interest at a rate of 7 1/4 % per annum and matured according to their terms on May 15, 2014.
	On August 24, 2012, in connection with the consummation of the acquisition and as provided in the merger agreement, NET entered into a supplemental indenture for the 1989 Debentures, which provided, among other things, that, in lieu of being convertible into shares of NET common stock, the 1989 Debentures would be convertible into the kind and amount of merger consideration that would have been received upon the consummation of the acquisition by a holder of the number of shares of NET common stock issuable upon conversion of such 1989 Debenture immediately preceding the effective time of the acquisition. The merger consideration was $1.35 per share.
	On August 24, 2012, NET sent a notice to the holders of the 1989 Debentures, notifying them that NET had elected to redeem on September 26, 2012 the entire outstanding aggregate principal amount of the 1989 Debentures. On the redemption date, the entire outstanding principal amount of the 1989 Debentures became due and payable at a redemption price equal to 100% of the principal amount of the 1989 Debentures plus accrued and unpaid interest to the redemption date. NET paid the aggregate principal amount of $23.7 million plus $0.6 million in accrued interest to the holders of the 1989 Debentures on September 26, 2012 and accordingly, at December 31, 2012, no obligation remained in connection with the Debentures.

LONGTERM_LIABILITIES

LONG-TERM LIABILITIES	12 Months Ended
	Dec. 31, 2014
Other Liabilities [Abstract]
LONG-TERM LIABILITIES	LONG-TERM LIABILITIES
	Long-term liabilities consist of the following (in thousands):
		December 31,
		2014			2013
	Capital lease obligations	$	70		$	154
	Deferred rent	3,160			3,057
	Restructuring	5,334			4,345
	Other	1,125			—
		9,689			7,556
	Current portion *	(4,443		)	(3,185		)
	Long-term liabilities, net of current portion	$	5,246		$	4,371
	* Includes $3.4 million at December 31, 2014 and $2.5 million at December 31, 2013 of current accrued restructuring reported as a component of Accrued expenses in the consolidated balance sheets.

STOCKHOLDER_RIGHTS_PLAN

STOCKHOLDER RIGHTS PLAN	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity Note [Abstract]
STOCKHOLDER RIGHTS PLAN	STOCKHOLDER RIGHTS PLAN
	On September 17, 2014, the Company entered into an amendment to its stockholder rights agreement adopted on June 26, 2008, as amended (the "Rights Plan"), to advance the final expiration date from June 26, 2015 to September 17, 2014. As a result of this amendment, effective as of the close of business on September 17, 2014, the Rights (as defined in the Rights Plan) expired and are no longer outstanding and the Rights Plan terminated by its terms.

COMMON_STOCK_REPURCHASES_AND_U

COMMON STOCK REPURCHASES AND UNDERWRITTEN OFFERING (Notes)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
COMMON STOCK REPURCHASES AND UNDERWRITTEN OFFERING	COMMON STOCK REPURCHASES AND UNDERWRITTEN OFFERING
	Stock Buyback Program
	On July 29, 2013, the Company announced that its Board of Directors had authorized a stock buyback program to repurchase up to $100 million of the Company's common stock from time to time on the open market or in privately negotiated transactions. The timing and amount of any shares repurchased will be determined by the Company's management based on its evaluation of market conditions and other factors. The Company may elect to implement a 10b5-1 repurchase program, which would permit shares to be repurchased when the Company might otherwise be precluded from doing so under insider trading laws. The buyback program does not have a fixed expiration date but may be suspended or discontinued at any time. The buyback program is being funded using the Company's working capital.
	During the year ended December 31, 2014, the Company spent $18.0 million, including transaction fees, to repurchase and retire 1.0 million shares of its common stock under the buyback program. During the year ended December 31, 2013, the Company spent $59.7 million, including transaction fees, to repurchase and retire 3.7 million shares of its common stock under the buyback program.
	At December 31, 2014, the Company had $22.8 million remaining under the stock buyback program for future purposes.
	Underwritten Offering
	On March 20, 2014, the Company announced the commencement of an underwritten public offering of 7.5 million shares of its common stock on behalf of Galahad Securities Limited and its affiliated entities (collectively, the "Legatum Group"). The underwriter of the offering was granted a 30-day option to purchase up to 1.125 million additional shares from the Legatum Group. The Legatum Group received all the proceeds from the underwritten offering; no shares in the underwritten offering were sold by Sonus or any of its officers or directors. Sonus purchased 4.3 million shares of its common stock from the underwriter for $17.4410 per share, the price equal to the price paid by the underwriter to the Legatum Group in the underwritten offering, for a total of $75.3 million, including transaction fees of $0.3 million. This repurchase was not completed under the Company's stock buyback program. Sonus funded the share repurchase with cash on hand. The repurchased shares were retired upon completion of the transaction.

STOCKBASED_COMPENSATION_PLANS

STOCK-BASED COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION PLANS	STOCK-BASED COMPENSATION PLANS
	Reverse Stock Split
	At its December 2, 2014 special meeting of stockholders, the Company's stockholders approved an amendment to the Company's Fourth Amended and Restated Certificate of Incorporation, as amended, to effect a reverse stock split of the Company's common stock, with the ratio, implementation and timing of such reverse stock split (within specified parameters) to be determined in the discretion of the Company's Board of Directors. In January 2015, the Reverse Stock Split Special Committee of the Company's Board of Directors set the ratio for the reverse stock split at one-for-five and such reverse stock split was made effective on the NASDAQ Global Select Market as of the commencement of trading on January 30, 2015.  As a result of the reverse stock split, the number of the Company's issued and outstanding shares was adjusted such that every five shares of common stock were converted into one share of common stock, reducing the authorized number of shares of the Company's common stock from 600,000,000 to 120,000,000. Proportional adjustments were also made to the Company's equity incentive plans, as well as to any outstanding restricted stock awards and stock options granted under such equity incentive plans to maintain the economic value of the awards.  Following the effective date of the reverse stock split, the par value of the common stock remained at $0.001 per share.
	2007 Stock Incentive Plan
	The Company's 2007 Stock Incentive Plan (the "2007 Plan") was approved at the Company's Annual Meeting of Stockholders held on November 12, 2007, and became effective on that date. The 2007 Plan provides for the award of options to purchase the Company's common stock ("stock options"), stock appreciation rights ("SARs"), restricted common stock ("restricted stock"), performance-based awards, restricted stock units ("RSUs") and other stock-based awards to employees, officers, directors (including those directors who are not employees or officers of the Company), consultants and advisors of the Company and its subsidiaries.
	At its December 2, 2014 special meeting of stockholders, the Company's stockholders approved amendments to the 2007 Plan (the "Amended 2007 Plan") to:
	•	Increase the number of shares available for future grant by 2 million shares;
	•	Increase the aggregate number of shares of the Company's common stock authorized for issuance under the 2007 Plan to include: (i) the number of shares of the Company's common stock that are reserved for future issuance under the Company's 2008 Stock Incentive Plan (the "2008 Plan") and the 2012 Amended Performance Technologies, Incorporated Omnibus Incentive Plan (the "2012 Plan," together with the 2008 Plan, the "Acquired Plans") immediately prior to the time this proposal was approved by stockholders (which number was 313,747 shares) and (ii) any shares of the Company's common stock subject to awards that are outstanding under the Acquired Plans immediately prior to the time this proposal was approved by stockholders (which number was 810,064 shares subject to outstanding options and 2,000 restricted shares, for an aggregate of 812,064 shares) that expire, are terminated, canceled, surrendered or forfeited, or are repurchased by the Company at their original issuance price pursuant to a contractual repurchase right under the Acquired Plans. Any shares granted under the 2008 Plan that are returned to the Company will be returned at the fungible rate of 1.25. The Acquired Plans will no longer be used for new grants;
	•	Increase the maximum number of shares that may be granted to any non-employee director under the 2007 Plan, from 20,000 shares to 40,000 shares per calendar year; and
	•	Revise the rate at which restricted stock, restricted stock units, performance awards and other stock unit awards are counted against the shares of common stock available for issuance under the 2007 Plan from 1.5 shares for every one share issued in connection with such award to 1.57 shares for every one share issued in connection with such award. Shares of common stock subject to awards that were granted under the 1.5 times ratio will return to the 2007 Plan upon forfeiture of such awards at the previous ratio of 1.5.
	At its June 12, 2013 annual meeting of stockholders, the Company's stockholders approved an amendment to the 2007 Plan, which increased the number of shares available for future grant by 4.2 million shares.
	At December 31, 2014, there were 3.4 million shares available for future issuance under the Amended 2007 Plan. Under the fungible share pool formula, the number of total shares available for future awards under the Amended 2007 Plan would be reduced by the fungible share pool multiple of 1.5 for each share of common stock included in an award other than a stock option or SAR award granted prior to December 2, 2014 and 1.57 for each share of common stock included in an award other than a stock option or SAR award granted on or after December 2, 2014. Accordingly, the total number of shares awarded in the future under the Amended 2007 Plan could be less than the number of shares currently available for issuance.
	2008 Stock Incentive Plan
	In connection with the acquisition of NET, the Company assumed NET's 2008 Equity Incentive Plan (the "NET 2008 Plan"), which provides for the award of stock options, SARs, restricted stock, performance-based awards and RSUs), and the number of shares available for grant under the 2008 Plan were converted to like Sonus equity awards (the "converted awards") using a conversion factor of 0.75, which was calculated based on the acquisition consideration of $1.35 per share of NET common stock divided by the average of the closing price of Sonus common stock for the ten consecutive days ending with the third trading day that preceded the closing date. This conversion factor was also used to convert the exercise prices of NET stock options to Sonus stock option exercise prices. The converted awards will vest under the same schedules as the respective NET stock options and NET RSUs.
	The fair values of the NET stock options assumed were estimated using a Black-Scholes option pricing model. The Company recorded $0.9 million as additional purchase consideration for the fair value of the assumed equity awards. The fair value of the assumed awards attributable to future stock-based compensation expense totaled $0.4 million, which was recorded over a weighted average period of approximately eight months.
	In December 2012, the Company's Board of Directors approved the re-naming of the NET 2008 Plan to the 2008 Stock Incentive Plan (the "2008 Plan"). At December 31, 2014, there were no shares available for future issuance under the 2008 Plan. Under the fungible pool formula, the number of total shares available for future awards under the 2008 Plan would be reduced by the fungible share pool multiple of 1.25 for each share of common stock included in an award other than a stock option or SAR award.
	At its December 2, 2014 special meeting of stockholders, the Company's stockholders approved moving all shares available for grant under the 2008 Plan to the Amended 2007 Plan and also voted that any outstanding awards under the 2008 Plan that in the future expired, terminated, canceled, surrendered or forfeited, or are repurchased by the Company at their original issuance price pursuant to a contractual repurchase right under the 2008 Plan shall be returned to the Amended 2007 Plan.
	2012 Stock Incentive Plan
	In connection with the acquisition of PT, the Company assumed PT's 2012 Amended Performance Technologies, Incorporated Omnibus Incentive Plan, which provides for the award of stock options, SARs, restricted stock, performance-based awards and RSUs to former employees of PT who subsequently became employees of Sonus and Sonus employees hired subsequent to the PT Acquisition Date. The Company also assumed all of the outstanding options to purchase common stock under the Performance Technologies, Incorporated 2003 Omnibus Incentive Plan (the "2003 Plan") and the Performance Technologies, Incorporated 2001 Stock Option Plan (the "2001 Plan"); however, no future equity awards may be granted under either the PT 2003 Plan or the PT 2001 Plan.
	The options to purchase PT common stock under the 2012 Plan, the 2003 Plan and the 2001 Plan were converted into options to purchase Sonus common stock (the "converted awards"), and the shares of PT common stock available for future grant under the 2012 Plan were converted into shares of Sonus common stock available for future grant, using a conversion factor of 1.23, which was calculated based on the acquisition consideration of $3.75 per share of PT's common stock divided by the average of the closing price of Sonus' common stock for the ten consecutive days ending with the third trading day that preceded the closing date. This conversion factor was also used to convert the exercise prices of PT stock options to Sonus stock option exercise prices. The converted awards will vest under the same schedules as the respective PT stock options.
	The fair values of the PT stock options assumed were estimated using a Black-Scholes option pricing model. The Company recorded $1.7 million as additional purchase consideration for the fair value of the assumed equity awards. The fair value of the assumed awards attributable to future stock-based compensation expense totaled $0.9 million, which is being recorded over a weighted average period of approximately one year.
	At its December 2, 2014 special meeting of stockholders, the Company's stockholders approved moving all shares available for grant under the 2012 Plan to the Amended 2007 Plan and also voted that any outstanding awards under the 2008 Plan that in the future expired, terminated, canceled, surrendered or forfeited, or are repurchased by the Company at their original issuance price pursuant to a contractual repurchase right under the 2012 Plan shall be returned to the Amended 2007 Plan.
	Executive and Board of Directors Equity Arrangements
	On June 11, 2014, the Company modified the stock options outstanding as of that date that had been granted to its non-employee members of the Board of Directors (the "Board Members") to extend the exercise period to the lesser of three years from the date that a Board Member stepped down from his or her position on the Board of Directors or the remaining contractual life of the respective stock options. In connection with this modification, the Company recorded $0.7 million of incremental stock-based compensation expense in 2014, and this expense is included as a component of General and administrative expense in the Company's consolidated statement of operations for the year ended December 31, 2014.
	On January 2, 2014, Raymond P. Dolan, the Company's President and Chief Executive Officer ("Mr. Dolan") elected to accept shares of restricted stock in lieu of base salary for the period from January 1, 2014 through December 31, 2014. Accordingly, the Company granted Mr. Dolan restricted stock (the "2014 Dolan Salary Shares") on January 2, 2014, with the number granted calculated by dividing an amount equal to 1.5 times Mr. Dolan's base salary for the period from January 1, 2014 through December 31, 2014 by the closing price of the Company's common stock on the date of grant. The 2014 Dolan Salary Shares vested on December 31, 2014. Effective September 16, 2014, Mr. Dolan's annual base salary was increased from $500,000 to $600,000. For the remainder of 2014, such increase was prorated and paid in cash and was not subject to any stock-for-cash election. The Company recorded stock-based compensation expense related to the 2014 Dolan Salary Shares ratably for the period of January 1, 2014 through December 31, 2014.
	On January 22, 2014, 21 of the Company's executives, including Mr. Dolan, were given the choice to receive all or half of their fiscal year 2014 bonuses (the "2014 Bonus"), if any were earned, in the form of shares of the Company's common stock (the "2014 Bonus Shares"). Each executive could also elect not to participate in this program and to earn his or her 2014 Bonus in the form of cash. The amount of the 2014 Bonus was determined by the Compensation Committee of the Company's Board of Directors (the "Compensation Committee") on February 19, 2015. The number of 2014 Bonus Shares that was granted to those executives who elected to receive their 2014 Bonus entirely in the form of shares of common stock was calculated by dividing an amount equal to 1.5 times each executive's 2014 Bonus earned by the closing price of the Company's common stock on January 2, 2014. The number of 2014 Bonus Shares that was granted to those executives who elected to receive one-half of their 2014 Bonus in the form of shares of common stock was calculated by dividing an amount equal to 1.5 times one-half of each executive's 2014 Bonus earned by the closing price of the Company's common stock on January 2, 2014, with the cash portion equal 50% of their respective 2014 Bonus earned. The 2014 Bonus Shares were granted on February 20, 2015 and vested immediately. Of the eligible executives, 17 elected to receive their entire 2014 Bonus in shares of common stock and 4 elected to receive 50% of their 2014 Bonus in shares of common stock and 50% in cash. The Company determined that the grant date criteria for accounting purposes for the 2014 Bonus Shares was met on July 9, 2014, and accordingly, has determined that the grant date fair value of the 2014 Bonus Shares is $19.25 per share, the closing price of the Company's common stock on that date, as adjusted to reflect the reverse stock split of the Company's common stock. The Company recorded expense through the grant date of February 20, 2015.
	In March 2013, 21 executives of the Company, including Mr. Dolan, elected to receive bonuses with respect to 2013 (collectively, the "2013 Bonus"), if any were earned, in the form of shares of the Company's common stock (collectively, the "2013 Bonus Shares"). The 2013 Bonus Shares, if any were granted, would be granted on a date concurrent with the timing of normal 2013 bonus payouts and would be fully vested as of the date of grant, with the number of 2013 Bonus Shares calculated by dividing amounts equal to 1.5 times the respective 2013 Bonus amounts earned, as determined by the Compensation Committee, by the closing price of the Company's common stock on the date of grant. The Company recorded stock-based compensation expense for the 2013 Bonus Shares commensurate with the expected achievement level represented by the Company's accrual for its company-wide incentive bonus program, as the performance metrics for each were consistent. On February 11, 2014, the Compensation Committee determined the achievement level for the 2013 Bonus Shares and also that such shares would be granted and vest on effective February 18, 2014. Accordingly, the Company granted 0.2 million 2013 Bonus Shares on February 18, 2014, based on the closing price of the Company's common stock on the date of grant. These shares are included in the amounts reported both as "Granted" and "Vested" in the restricted stock grant table below.
	On February 14, 2013, the Compensation Committee determined that eight executives of the Company, excluding Mr. Dolan, would receive their bonuses with respect to 2012 in the form of restricted shares of the Company's common stock equal to 100% of their respective target bonus amounts for 2012 (collectively, the "Executive Bonus Shares"). The number of shares granted to each executive was calculated by dividing his/her target bonus amount by the closing price of the Company's common stock on February 15, 2013, the date of grant. The Executive Bonus Shares vested 50% on August 15, 2013 and the remaining 50% vested on February 15, 2014. The Company accrued for the cash payment of bonuses at the expected company-wide cash payout percentage amount at December 31, 2012, which amounts were less than the target bonus amounts for each individual. The Company recorded the expense related to the Executive Bonus Shares as stock-based compensation expense through February 15, 2014.
	On August 7, 2012, Mr. Dolan elected to receive his year 2012 target bonus, if earned, in the form of restricted shares (the “Dolan Bonus Shares”). On August 10, 2012, the Company granted Mr. Dolan shares of restricted stock which equaled Mr. Dolan's potential 2012 bonus at the maximum level of achievement (150% of Mr. Dolan's annual base salary), divided by the closing price of the Company's common stock on the date of grant. During 2012, the Company recorded stock-based compensation expense for the Dolan Bonus Shares commensurate with the expected achievement level represented by the Company's accrual for its company-wide incentive bonus program, as the performance metrics for each were consistent. 50% of the Dolan Bonus Shares vested on August 15, 2013 and the remaining 50% vested on February 15, 2014. The Company recorded the unamortized expense related to the Dolan Bonus Shares through February 15, 2014.
	Stock Options
	Options are issued to purchase shares of common stock of the Company at prices that are equal to the fair market value of the shares on the date the option is granted. Options generally vest over a period of four years, with 25% of the shares subject to the option vesting on the first anniversary of the grant date and the remaining 75% vesting in equal monthly increments thereafter through the fourth anniversary of the grant date. Options granted under the Amended 2007 Plan generally expire ten years from the date of grant. Options granted under the 2008 Plan generally expire seven years from the date of grant. Options granted under the 2012 Plan generally expire five years from the date of grant. The grant date fair value of options, adjusted for estimated forfeitures, is recognized as expense on a straight-line basis over the requisite service period, which is generally the vesting period. Forfeitures are estimated based on historical experience.
	The activity related to the Company's outstanding stock options during the year ended December 31, 2014 is as follows:
		Number of			Weighted			Weighted		Aggregate
		Shares			Average			Average		Intrinsic Value
					Exercise Price			Remaining		(in thousands)
								Contractual Term
								(years)
	Outstanding at January 1, 2014	6,627,137			$	16.11
	Granted	2,331,174			$	17.97
	PT outstanding options converted to Sonus options	256,548			$	8.65
	Exercised	(806,385	)		$	12.64
	Forfeited	(548,826	)		$	14.66
	Expired	(338,216	)		$	25.89
	Outstanding at December 31, 2014	7,521,432			$	16.47		6.91		$	31,319
	Vested or expected to vest at December 31, 2014	6,985,686			$	16.47		6.77		$	29,528
	Exercisable at December 31, 2014	3,651,057			$	16.86		5.14		$	16,809
	The grant date fair values of options to purchase common stock granted in the years ended December 31, 2014, 2013 and 2012 were estimated using the Black-Scholes valuation model with the following assumptions:
		Year ended December 31,
		2014		2013		2012
	Risk-free interest rate	1.53%-2.70%		0.82%-1.71%		0.67%-0.89%
	Expected dividends	—		—		—
	Weighted average volatility	60.80%		63.20%		67.40%
	Expected life (years)	4.5-6.0		4.5-6.0		4.5
	The risk-free interest rate used is the average U.S. Treasury Constant Maturities Rate for the expected life of the award. The expected dividend yield of zero is based on the fact that the Company has never paid dividends and has no present intention to pay cash dividends. The expected life for stock options is based on a combination of the Company's historical option patterns and expectations of future employee actions.
	The weighted average grant-date fair values of options granted during the year were $8.32 for the year ended December 31, 2014, $7.71 for the year ended December 31, 2013 and $6.44 for the year ended December 31, 2012.
	The total intrinsic values of options exercised during the year were $5.1 million for the year ended December 31, 2014, $1.3 million for the year ended December 31, 2013 and $0.2 million for the year ended December 31, 2012.
	The Company received cash from option exercises of $10.1 million in the year ended December 31, 2014, $2.7 million in the year ended December 31, 2013 and $0.3 million in the year ended December 31, 2012.
	Restricted Stock Grants - Restricted Stock Awards and Restricted Stock Units
	The Company's outstanding restricted stock grants consist of both restricted stock awards ("RSAs") and RSUs. During the years ended December 31, 2014, 2013 and 2012, the Company had no unvested RSUs other than those converted in connection with the NET acquisition; all of which were fully vested by December 31, 2013. Recipients of RSAs have voting rights and rights to receive dividends, if declared. RSAs generally vest 25% on the first anniversary of the grant date, with the remaining 75% vesting in equal increments semi-annually thereafter. The grant date fair value of restricted stock grants, adjusted for estimated forfeitures, is recognized as expense on a straight-line basis over the requisite service period. The fair value of restricted stock grants is determined based on the market value of the Company's shares on the date of grant.
	The activity related to the Company's unvested restricted stock grants for the year ended December 31, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
Unvested balance at January 1, 2014	247,747			$	14.08
Granted	553,609			$	17.03
Vested	(428,674	)		$	15.63
Forfeited	(2,500	)		$	7
Unvested balance at December 31, 2014	370,182			$	16.74
The total fair value of restricted stock grant shares vested was $6.7 million in the year ended December 31, 2014, $2.4 million in the year ended December 31, 2013 and $1.8 million in the year ended December 31, 2012.
Performance-Based Stock Awards
Similar to recipients of RSAs, recipients of performance-based stock awards have voting rights and rights to dividends, if declared. The Company begins to record stock-based compensation expense for performance-based stock awards at the time that it becomes probable that the respective performance conditions will be achieved. The Company continues to recognize the grant date fair value of performance-based stock awards through the vest date of the respective awards so long as it remains probable that the related performance conditions will be satisfied.
The activity related to the Company's performance-based stock awards for the year ended December 31, 2014 is as follows:
	Shares			Weighted
				Average
				Grant Date
				Fair Value
Unvested balance at January 1, 2014	211,906			$	12.98
Granted	—			$	—
Vested	(136,526	)		$	12.63
Forfeited	(41,145	)		$	13.6
Unvested balance at December 31, 2014	34,235			$	13.6
On February 14, 2013, the Compensation Committee took certain actions regarding performance-based stock awards that had been awarded in previous years but for which the grant date criteria had not been met as of December 31, 2012. These actions included determining that a certain number of these performance-based shares would vest as of February 15, 2013 (the “Vested Performance Shares”) and subjecting the remaining performance-based shares (the “Future Performance Shares”) to further performance and service conditions. On July 26, 2013, the Compensation Committee determined that the performance conditions related to the Future Performance Shares had been satisfied based on the Company's performance for the six months ended June 28, 2013 and, accordingly, all of the Future Performance Shares will vest contingent upon continued employment with the Company on the vesting dates. The Company is recording the unamortized expense related to the Future Performance Shares based on the vesting dates of the respective awards. The unvested Future Performance Shares will vest fully in 2015.
ESPP
The ESPP is designed to provide eligible employees of the Company and its participating subsidiaries an opportunity to purchase common stock of the Company through accumulated payroll deductions.
The ESPP provides for six-month consecutive offering periods. Prior to March 1, 2014, the purchase price of the stock was equal to 85% of the market price on the last day of the offering period. At the February 2014 meeting of the Board of Directors, the ESPP was amended, effective March 1, 2014, to provide for six-month consecutive offering periods with the purchase price of the stock equal to 85% of the lesser of the market price on the first or last day of the offering period. The maximum number of shares of common stock an employee may purchase during each offering period is 500, subject to certain adjustments pursuant to the ESPP.
At December 31, 2014, 5.0 million shares, the maximum number of shares that may be issued under the ESPP, were authorized and 2.1 million shares were available under the ESPP for future issuance.
Stock-Based Compensation
The consolidated statements of operations include stock-based compensation for the years ended December 31, 2014, 2013 and 2012 as follows (in thousands):
	Year ended December 31,
	2014				2013			2012
Product cost of revenue	$	337			$	181		$	162
Service cost of revenue	1,449				1,050			813
Research and development	5,759				3,616			2,297
Sales and marketing	5,437				4,780			2,006
General and administrative	10,932				8,246			3,725
	$	23,914			$	17,873		$	9,003
There is no income tax benefit for employee stock-based compensation expense for the years ended December 31, 2014, 2013 and 2012 due to the valuation allowance recorded.
At December 31, 2014, there was $28.0 million, net of expected forfeitures, of unrecognized stock-based compensation expense related to unvested stock options, RSAs and performance-based stock awards. This expense is expected to be recognized over a weighted average period of approximately three years.
Common Stock Reserved
Common stock reserved for future issuance at December 31, 2014 consists of the following:
Amended 2007 Plan	3,446,366
ESPP	2,139,824
	5,586,190
The Company's policy is to issue authorized but unissued shares upon the exercise of stock options, grant restricted common stock and performance-based stock awards, and authorize the purchase of shares of the Company's common stock under the ESPP.

EMPLOYEE_DEFINED_CONTRIBUTION_

EMPLOYEE DEFINED CONTRIBUTION PLAN	12 Months Ended
	Dec. 31, 2014
Compensation and Retirement Disclosure [Abstract]
EMPLOYEE DEFINED CONTRIBUTION PLAN	EMPLOYEE DEFINED CONTRIBUTION PLAN
	In the year ended December 31, 2012, the Company provided a matching contribution of 50% of employee contributions to its 401(k) savings plan, up to a maximum match of $3,500 per employee per year. The Company elected not to make a matching contribution in 2014 and 2013 and, accordingly, the Company did not record expense related to its 401(k) savings plan in the years ended December 31, 2014 or 2013. The Company recorded expense related to its 401(k) savings plan of $1.7 million in the year ended December 31, 2012.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES
	The components of income (loss) from continuing operations before income taxes consist of the following (in thousands):
		Year ended December 31,
		2014				2013				2012
	Loss before income taxes:
	United States	$	(16,582	)		$	(21,076	)		$	(49,337	)
	Foreign	1,941				409				1,609
		$	(14,641	)		$	(20,667	)		$	(47,728	)
	The provision (benefit) for income taxes from continuing operations consists of the following (in thousands):
		Year ended December 31,
		2014				2013				2012
	Provision (benefit) for income taxes:
	Current:
	Federal	$	23			$	14			$	14
	State	150				150				105
	Foreign	926				1,696				1,465
	Total current	1,099				1,860				1,584
	Deferred:
	Federal	(3,885		)		(1,911		)		(12,441		)
	State	(1,656		)		(103		)		(1,680		)
	Foreign	414				(1,081		)		607
	Change in valuation allowance	6,242				2,687				14,371
	Total deferred	1,115				(408		)		857
	Total	$	2,214			$	1,452			$	2,441
	A reconciliation of the Company's effective tax rate for continuing operations to the statutory federal rate is as follows:
		Year ended December 31,
		2014			2013			2012
	U.S. statutory income tax rate	(35.0	)%		(35.0	)%		(35.0	)%
	State income taxes, net of federal benefit	(4.9	)		0.4			(3.6	)
	Foreign income taxes	5.1			1.3			3.2
	Capital loss expiration	—			24			—
	Foreign deemed dividends	11.5			1.8			2.1
	Stock-based compensation	12			7.6			3.4
	Tax credits	(14.6	)		(6.1	)		(0.7	)
	Deferred cost of goods sold elimination	—			—			(1.2	)
	Valuation allowance	29.8			9.9			35.5
	Goodwill amortization	4.8			3.3			0.5
	Meals and entertainment	2.5			1.3			0.7
	Tax gain on sale of acquired assets	4.2			—			—
	Other, net	(0.3	)		(1.5	)		0.2
	Effective income tax rate	15.1	%		7	%		5.1	%
	The following is a summary of the significant components of deferred income tax assets and liabilities (in thousands):
		December 31,
		2014				2013
	Assets:
	Net operating loss carryforwards	$	74,717			$	64,811
	Research and development tax credits	24,978				21,401
	Other tax credits	91				160
	Intangible assets	4,808				2,530
	Deferred revenue	1,911				4,143
	Accrued expenses	10,619				10,519
	Inventory	5,713				6,498
	Stock-based compensation	12,913				9,263
	Other temporary differences	3,924				3,642
		139,674				122,967
	Valuation allowance	(137,640		)		(119,616		)
	Total deferred tax assets	2,034				3,351
	Liabilities:
	Purchased intangible assets	(1,623		)		(922		)
	Unrealized gain on available-for-sale securities	—				(574		)
	Total deferred tax liabilities	(1,623		)		(1,496		)
	Total net deferred tax assets	$	411			$	1,855
	Reported as:
	Deferred income taxes - current assets	$	991			$	656
Deferred income taxes - noncurrent assets	1,043				—
Deferred income taxes - noncurrent liabilities	(1,623		)		1,199
	$	411			$	1,855
At December 31, 2014, the Company had cumulative net operating losses ("NOL") of $215.0 million for federal income tax purposes and $109.0 million for state income tax purposes. The federal NOL carryforwards expire at various dates from 2020 through 2034. The state NOL expires at various dates from 2015 through 2034. Of the federal NOL, $138.0 million is attributable to stock option deductions. The Company's federal NOL carryforwards for tax return purposes are $22.4 million greater than its recognized federal NOL for financial reporting purposes, primarily due to excess tax benefits (stock compensation deductions in excess of book compensation costs) not recognized for financial statement purposes until realized. The tax benefit of this loss would be recognized for financial statement purposes in the period in which the tax benefit reduces income taxes payable, which will not be recognized until the Company recognizes a reduction in taxes payable from all other NOL carryforwards. In addition, the Company has $12.9 million of deferred tax assets as of December 31, 2014 related to compensation expenses recognized for financial reporting purposes that are not deductible for tax purposes until options are exercised or shares vest. The ultimate realization of the benefit related to stock options is directly associated with the price of the Company's common stock. Employees will not exercise the underlying options unless the current market price exceeds the option exercise price.
With respect to non-U.S. NOL carryovers, the Company's United Kingdom subsidiary has a current year estimated NOL of approximately $0.1 million and its Japan subsidiary has a current year estimated NOL of approximately $0.9 million.
The Company also has available federal and state research and development credit carryforwards of approximately $25 million that expire at various dates from 2015 through 2034.
During 2013, $14.1 million of capital loss carryover resulting from the Company's sale of its Zynetix subsidiary on November 26, 2008 expired. The capital loss was only available to offset capital gains. Because it was not more likely than not that the Company would realize a benefit prior to the expiration of the capital loss carryforward, a full valuation allowance had been established against the $5.5 million tax benefit associated with this capital loss.
During 2014 and 2013, the Company performed an analysis to determine if, based on all available evidence, it considered it more likely than not that some portion or all of the recorded deferred tax assets will not be realized in a future period. As a result of the Company's evaluation, the Company concluded that there was insufficient positive evidence to overcome the more objective negative evidence related to its cumulative losses and other factors. Accordingly, the Company has maintained a valuation allowance against its domestic deferred tax asset amounting to $137.6 million at December 31, 2014 and $119.6 million at December 31, 2013.
A reconciliation of the Company's unrecognized tax benefits is as follows (in thousands):
	2014				2013				2012
Unrecognized tax benefits at January 1	$	8,861			$	8,847			$	10,004
Increases related to current year tax positions	14				14				14
Decreases related to prior period tax positions	—				—				(1,171		)
Unrecognized tax benefits at December 31	$	8,875			$	8,861			$	8,847
The Company recorded liabilities for potential penalties and interest of $14,000 for each of the years ended December 31, 2014, 2013 and 2012. The Company does not expect its unrecognized tax benefits to change materially over the next 12 months. Due to the Company's valuation allowance at December 31, 2014, none of the Company's unrecognized tax benefits, if recognized, would affect the effective tax rate.
The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction, as well as various state and foreign jurisdictions. Generally, the tax years 2012 through 2014 remain open to examination by the major taxing jurisdictions to which the Company is subject. The Company's federal NOLs generated prior to 2003 could be adjusted on examination even though the year in which the loss was generated is otherwise closed by the statute of limitations. The Company's primary state jurisdiction, Massachusetts, has open periods from 2011 through 2013.
The acquisition of NET was accounted for as a nontaxable business combination and the Company carried over the existing tax basis of the acquired assets and liabilities. Deferred taxes were recorded as part of the business combination based on the differences between the tax basis of the acquired assets or liabilities and their reported amounts for financial reporting purposes. The Company concluded that there was insufficient positive evidence to overcome the more objective negative evidence related to cumulative losses and other factors. Accordingly, the Company recorded a valuation allowance against the majority of the acquired deferred tax assets.
With respect to the acquisition of NET, during the second quarter of 2013, the Company made an election under Section 338(g) of the Internal Revenue Code to have the acquisition transaction treated as an asset acquisition (i.e., a taxable transaction). The election is not considered part of the business combination and resulted in a step-up in the acquired assets and liabilities to fair market value for tax purposes. During the third quarter of 2013, as a result of the election, the Company reversed all of the deferred taxes related to NET's assets, liabilities and net operating loss carryovers and the related valuation allowance that were recorded in the business combination. The resulting taxable gain from the election was fully offset by NET's operating loss carryovers and no taxes were paid by the Company as a result of the election.
The acquisition of PT was accounted for as a taxable business combination and the Company carried over the existing tax basis of the acquired assets and liabilities as the Company did not make the election under Section 338(g) of the Internal Revenue Code to have the transaction treated as an asset acquisition election to step up the basis in the acquired assets and liabilities to fair market value for tax purposes. Deferred taxes were recorded as part of the business combination based on the differences between the tax basis of the acquired assets or liabilities and their reported amounts for financial reporting purposes. The Company concluded that there was insufficient positive evidence to overcome the more objective negative evidence related to cumulative losses and other factors. Accordingly, the Company recorded a valuation allowance against the acquired deferred tax assets. As a result of the change in control of PT, the NOL and credit carryforwards are limited under Internal Revenue Code Section 382.
The Company acquired approximately $26 million of federal and state net operating loss carryforwards and federal and state research and development credit carryforwards as a result of the PT acquisition. Under the provisions of the Internal Revenue Code, the net operating losses and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating losses and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has not performed a comprehensive Section 382 study to determine any potential loss limitation with regard to the net operating loss carryforwards and tax credits acquired as a result of the PT acquisition.

MAJOR_CUSTOMERS

MAJOR CUSTOMERS	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
MAJOR CUSTOMERS	MAJOR CUSTOMERS
	The following customer contributed 10% or more of the Company's revenue in each of the years ended December 31, 2014, 2013 and 2012:
		Year ended December 31,
		2014	2013	2012
	AT&T	19%	15%	20%
	There were no other customers that contributed 10% or more of the Company's revenue in any of the years ended December 31, 2014, 2013 or 2012.
	At December 31, 2014, no customer accounted for 10% or more of the Company's accounts receivable balance. At December 31, 2013, one customer accounted for 10% or more of the Company's accounts receivable balance, representing approximately 13% of the Company's accounts receivable balance. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable. The Company maintains an allowance for doubtful accounts and such losses have been within management's expectations.

GEOGRAPHIC_AND_OPERATING_SEGME

GEOGRAPHIC AND OPERATING SEGMENT INFORMATION GEOGRAPHIC AND OPERATING SEGMENT INFORMATION	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
GEOGRAPHIC INFORMATION	GEOGRAPHIC AND SEGMENT INFORMATION
	The Company's classification of revenue by geographic area is determined by the location of the Company's customers. The following table summarizes revenue by geographic area as a percentage of total revenue:
		Year ended December 31,
		2014		2013			2012
	United States	71	%	69	%		68	%
	Europe, Middle East and Africa	13		12			13
	Japan	9		12			14
	Other Asia Pacific	5		5			4
	Other	2		2			1
		100	%	100	%		100	%
	The Company's service revenue is comprised of the following (in thousands):
		Year ended December 31,
		2014			2013				2012
	Maintenance	$	90,003		$	84,698			$	76,423
	Professional services	23,868			24,763				24,385
		$	113,871		$	109,461			$	100,808

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES
	Leases
	The Company leases its facilities under operating leases, which expire at various times through 2019. The Company is responsible for certain real estate taxes, utilities and maintenance costs under these leases. The Company's corporate headquarters is located in a leased facility in Westford, Massachusetts, consisting of 97,500 square feet under a lease that expires in August 2018.
	Escalation clauses, free rent and other lease concessions are recognized on a straight-line basis over the minimum lease term. Rent expense was $6.1 million for the year ended December 31, 2014, $5.5 million for the year ended December 31, 2013 and $5.0 million for the year ended December 31, 2012.
	Future minimum payments under operating lease arrangements as of December 31, 2014 are as follows (in thousands):
	Years ending December 31,
	2015	$	6,330
	2016	5,506
	2017	3,855
	2018	2,929
	2019	1,351
	Thereafter	38
		$	20,009
	Litigation and Contingencies
	The Company is often a party to disputes and legal proceedings that it considers routine and incidental to its business. In the normal course of business, the Company enters into contractual commitments to purchase services, materials, components, and finished goods from suppliers. Under agreements with certain contract manufacturers, the Company may be liable for purchased raw materials procured for the Company by the contract manufacturer. Management does not expect the results of any of these actions to have a material effect on the Company's business or consolidated financial statements.

SUBSEQUENT_EVENT_Notes

SUBSEQUENT EVENT (Notes)	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT
	On January 2, 2015, the Company acquired from Treq Labs, Inc. (the "Treq") certain assets related to Treq's business of designing, developing, marketing, selling, servicing and maintaining software defined networking ("SDN") technology, SDN controller software and SDN management software (the "SDN Business"). Treq's SDN technology provides solutions that optimize networks for voice, video and UC for both enterprise and service provider customers. The Company believes that the acquisition of the SDN Business will accelerate Sonus' delivery of its SDN strategy. In consideration for the acquisition of the SDN Business, the Company paid $10.1 million in cash and entered into an Earn-Out Agreement, dated as of January 2, 2015, with Treq and Karl F. May, the seller representative in the transaction (the "Earn-Out Agreement"), under which the Company has agreed to issue up to an aggregate of 1.3 million shares of common stock over a three-year period subsequent to the closing if aggregate revenue thresholds of at least $60 million are achieved by the SDN Business during that period, and up to an aggregate of an additional 2.2 million shares (3.5 million shares in total) if aggregate revenue thresholds of at least $150 million are achieved by the SDN Business during that period. If the initial revenue thresholds are not met, no shares will be issued. Any shares issued pursuant to the Earn-Out Agreement will be issued in reliance on the exemption from registration available under Section 4(a)(2) of the Securities Act of 1933, as amended (the "Securities Act") and will be subsequently registered for resale under the Securities Act by the Company. The Company is in the process of determining the fair values of assets acquired and liabilities assumed and accordingly, has not disclosed this information herein.

QUARTERLY_RESULTS_UNAUDITED

QUARTERLY RESULTS (UNAUDITED)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY RESULTS (UNAUDITED)	QUARTERLY RESULTS (UNAUDITED)
	The following tables present the Company's quarterly operating results for the years ended December 31, 2014 and 2013. The information for each of these quarters is unaudited and has been prepared on the same basis as the audited consolidated financial statements. In the opinion of management, all necessary adjustments, consisting only of normal recurring adjustments, have been included to present fairly the unaudited consolidated quarterly results when read in conjunction with the Company's audited consolidated financial statements and related notes.
		First			Second			Third			Fourth
		Quarter (1)			Quarter			Quarter			Quarter
		(In thousands, except per share data)
	Fiscal 2014
	Revenue	$	70,742		$	75,570		$	73,216		$	76,798
	Cost of revenue	24,319			28,282			25,314			25,006
	Gross profit	$	46,423		$	47,288		$	47,902		$	51,792
	Loss from operations	$	(5,791	)	$	(4,801	)	$	(4,715	)	$	(1,945	)
	Net loss	$	(3,953	)	$	(5,497	)	$	(5,213	)	$	(2,192	)
	Loss per share (2):
	Basic	$	(0.07	)	$	(0.11	)	$	(0.11	)	$	(0.04	)
	Diluted	$	(0.07	)	$	(0.11	)	$	(0.11	)	$	(0.04	)
	Shares used in computing loss per share:
	Basic	53,080			49,424			49,291			49,361
	Diluted	53,080			49,424			49,291			49,361
		First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter
		(In thousands, except per share data)
	Fiscal 2013
	Revenue	$	63,288		$	69,193		$	68,099		$	76,153
	Cost of revenue	25,486			25,185			25,835			27,767
	Gross profit	$	37,802		$	44,008		$	42,264		$	48,386
	Loss from operations	$	(13,472	)	$	(4,633	)	$	(2,911	)	$	(59	)
	Net income (loss)	$	(13,748	)	$	(4,870	)	$	(3,773	)	$	272
	Income (loss) per share (2):
	Basic	$	(0.24	)	$	(0.09	)	$	(0.07	)	$	0.01
	Diluted	$	(0.24	)	$	(0.09	)	$	(0.07	)	$	—
	Shares used in computing income (loss) per share:
	Basic	56,308			56,478			55,855			54,188
	Diluted	56,308			56,478			55,855			54,699
	__________________________________
	-1	Includes the results of PT for the period subsequent to February 19, 2014.
	-2	Earnings (loss) per share is calculated independently for each of the quarters presented; accordingly, the sum of the quarterly earnings (loss) per share amounts may not equal the total calculated for the year.

BASIS_OF_PRESENTATION_AND_SUMM1

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Basis of Presentation	BASIS OF PRESENTATION
	The consolidated financial statements have been prepared in United States dollars, in accordance with accounting principles generally accepted in the United States ("GAAP").
	The Company reports its first, second and third quarters on a 4-4-5 basis, with the quarter ending on the Friday closest to the last day of each third month. In 2014, the Company's first quarter ended on March 28, 2014, the second quarter ended on June 27, 2014 and the third quarter ended on September 26, 2014. In 2013, the Company's first quarter ended on March 29, 2013, the second quarter ended on June 28, 2013 and the third quarter ended on September 27, 2013. In 2012, the Company's first quarter ended on March 30, 2012, the second quarter ended on June 29, 2012 and the third quarter ended on September 28, 2012. The Company's fiscal year ends on December 31.
	In December 2014, the Company's stockholders approved an amendment to Sonus' Fourth Amended and Restated Certificate of Incorporation, as amended, to effect a reverse stock split of its common stock, with the ratio, implementation and timing of such reverse stock split (within specified parameters) to be determined at the discretion of the Company's Board of Directors. In January 2015, the Reverse Stock Split Special Committee of the Board of Directors set the ratio for the reverse stock split at one-for-five and such reverse stock split was made effective on the NASDAQ Global Select Market as of the commencement of trading on January 30, 2015.  As a result of the reverse stock split, the number of the Company's issued and outstanding shares was adjusted such that every five shares of common stock were converted into one share of common stock, reducing the authorized number of shares of the Company's common stock from 600,000,000 to 120,000,000. Proportional adjustments were also made to the Company's equity incentive plans, as well as to any outstanding restricted stock awards and stock options granted under such equity incentive plans to maintain the economic value of the awards.  Following the effective date of the reverse stock split, the par value of the common stock remained at $0.001 per share. Unless otherwise indicated, all references herein to shares outstanding and share issuances have been adjusted to give effect to the aforementioned reverse stock split.
	On February 19, 2014 (the "PT Acquisition Date"), the Company completed the acquisition of Performance Technologies, Incorporated ("PT"). The financial results of PT are included in the Company's consolidated financial statements for the periods subsequent to the PT Acquisition Date.
	On August 24, 2012, the Company completed the acquisition of Network Equipment Technologies, Inc. (“NET”). The financial results of NET have been included in the Company's consolidated financial statements for the periods subsequent to its acquisition.
Principles of Consolidation	Principles of Consolidation
	The accompanying consolidated financial statements include the accounts of Sonus and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates and Judgments	Use of Estimates and Judgments
	The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and judgments relied upon in preparing these consolidated financial statements include accounting for business combinations, revenue recognition for multiple element arrangements, inventory valuations, assumptions used to determine the fair value of stock-based compensation, intangible assets and goodwill valuations, legal contingencies and recoverability of Sonus' net deferred tax assets and the related valuation allowances. Sonus regularly assesses these estimates and records changes in estimates in the period in which they become known. Sonus bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Business Combinations	Business Combinations
	The Company recognizes identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed and represents the expected future economic benefits arising from other assets acquired in the business combination that are not individually identified and separately recognized. 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, its 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 that it 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.
Revenue Recognition	Revenue Recognition
	The Company recognizes revenue from sales when persuasive evidence of an arrangement exists, delivery has occurred, the sale price is fixed or determinable, and collectability of the related receivable is probable. In instances where customer acceptance is required, revenue is deferred until the acceptance has been achieved. When fees for products or services are not fixed and determinable, the Company defers the recording of receivables, deferred revenue and revenue until such time as the fees become due or are collected.
	Revenue from maintenance and support services is recognized ratably over the service period. Maintenance revenue is deferred until the associated product is accepted by the customer and all other revenue recognition criteria have been met. Maintenance and support services include telephone support, return and repair support and unspecified rights to product upgrades and enhancements. Revenue from other professional services is typically recognized as the services are delivered if all other revenue recognition criteria have been met.
	The Company's products typically have both software and non-software components that function together to deliver the products' essential functionality. In addition, hardware sold generally cannot be used apart from the software. Therefore, the Company considers its principal products to be both software and hardware-related. Many of the Company's sales involve multiple element arrangements that include product, maintenance and various professional services.
	Our products typically have both software and non-software components that function together to deliver the products' essential functionality. Many of our sales involve multiple-element arrangements that include both software and hardware-related products, maintenance and various professional services. We recognize revenue in accordance with the provisions of Accounting Standards Codification ("ASC") 605-25, Revenue Recognition - Multiple-Element Arrangements ("ASC 605-25") transactions that include both hardware and software components. We recognize revenue from stand-alone software sales under the software revenue recognition guidance in ASC 985-605, Software - Revenue Recognition ("ASC 985-605"). The Company limits the amount of revenue recognized for delivered elements to the amount that is not contingent on the future delivery of products or services, future performance obligations, or subject to customer-specific return or refund privileges.
	For multiple-element arrangements that include both software-only products and non-software products, the Company allocates the total arrangement consideration to the software-only deliverables as a group and to the individual non-software deliverables based on their relative selling prices. If an undelivered element (such as maintenance and support services) relates to both the software-only and non-software deliverables, the Company bifurcates the consideration allocated to the undelivered element (such as maintenance and support services) into a non-software component and the software-only component using the relative selling price method. The consideration allocated to the non-software and software-only deliverables is recognized in accordance with the guidance as discussed in this note.
	Under ASC 985-605, revenue for any undelivered elements that are considered not essential to the functionality of the product and for which vendor-specific objective evidence of selling price (“VSOE”) has been established is deferred and recognized upon delivery utilizing the residual method. If the Company has undelivered product for which VSOE has not been established, it defers all revenue on the entire arrangement until VSOE is established or until such elements are delivered, provided that all other revenue recognition criteria are met. If the Company has undelivered services for which VSOE has not been established, the entire arrangement is recognized as revenue over the longest remaining service period from the point in time that all services have commenced and all products have been delivered, provided that all other revenue recognition criteria are met.
	For transactions that include multiple elements, arrangement consideration is allocated to each element based on the relative selling prices of all of the elements in the arrangement using the fair value hierarchy as required by ASC 605-25.
	The Company establishes VSOE based upon the price charged when the same element is sold separately or established by management having the relevant pricing authority. The Company has VSOE for its maintenance and support services and certain professional services. When VSOE exists it is used to determine the selling price of a deliverable. The Company has not been able to establish VSOE of any of its products and for certain of its services because the Company has not sold such products or services on a stand-alone basis, has not priced its products or services within a narrow range, or has limited sales history.
	When VSOE is not established, the Company attempts to establish the selling price of each element based on third-party evidence of selling price (“TPE”). The Company's solution typically differs from that of its peers as there are no similar or interchangeable competitor products or services. The Company's various product, service and maintenance offerings contain a significant level of unique features and functionality and therefore, comparable pricing of competitors' products and services with similar functionality cannot be obtained. Accordingly, the Company is not able to determine TPE for its products or services.
	When the Company is unable to establish selling price using VSOE or TPE, the Company uses estimated selling price (“ESP”) in its allocation of arrangement consideration for the relevant deliverables. The objective of ESP is to determine the price at which the Company would transact a sale if a product or service was sold on a stand-alone basis. The Company determines ESP for its products and certain services by considering multiple factors including, but not limited to, overall market conditions, including geographic or regional-specific market factors, profit objectives and historical pricing practices for such deliverables. The determination of ESP is a formal process within the Company that includes review and approval by the Company's management.
	Deferred revenue typically includes customer deposits and amounts associated with partial product shipments and maintenance or service contracts. Deferred revenue expected to be recognized as revenue more than one year subsequent to the balance sheet date is reported as a component of long-term liabilities in the condensed consolidated balance sheets. The Company defers recognition of incremental direct costs, such as cost of goods, third-party installations and commissions, until recognition of the related revenue. Such costs are classified as current assets if the deferred revenue is initially classified as current and noncurrent assets if the related deferred revenue is initially classified as long-term.
	The Company excludes any taxes assessed by a governmental authority that are directly imposed on a revenue-producing transaction (i.e., sales, use, value added) from its revenue and costs. Reimbursement received for out-of-pocket expenses and shipping costs is recorded as revenue.
	The Company sells the majority of its products directly to its end customers. For products sold to resellers and distributors, the Company recognizes revenue on a sell-through basis.
Financial Instruments	Financial Instruments
	The carrying amounts of Sonus' financial instruments, which include cash equivalents, investments, accounts receivable, accounts payable and convertible subordinated debt approximate their fair values.
	All investments in marketable securities are classified as available-for-sale and are reported at fair value, with unrealized gains and losses excluded from earnings and reported, net of tax, in Accumulated other comprehensive loss, which is a component of stockholders' equity. Unrealized losses that are determined to be other-than-temporary, based on current and expected market conditions, are recognized in earnings. Declines in fair value determined to be credit-related are charged to earnings. The cost of marketable securities sold is determined by the specific identification method.
	Financial instruments with remaining maturities or that are due within one year from the balance sheet date are classified as current. Financial instruments with remaining maturities or that are payable more than one year from the balance sheet date are classified as noncurrent.
Cash and Cash Equivalents	Cash and Cash Equivalents
	Cash equivalents are stated at fair value, with unrealized gains and losses excluded from earnings and reported, net of tax, in Accumulated other comprehensive income (loss). Cash equivalents are liquid securities that have remaining maturities of three months or less at the date of purchase.
Restricted Cash	Restricted Cash
	The Company classifies as restricted cash all cash pledged as collateral to secure long-term obligations and all cash whose use is otherwise limited by contractual provisions. Restricted cash is recorded within other assets on the consolidated balance sheet.
Foreign Currency Translation	Foreign Currency Translation
	For foreign subsidiaries where the functional currency is the local currency, assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Revenue and expenses are translated at average rates of exchange prevailing during each period. Translation adjustments for these subsidiaries are included in Accumulated other comprehensive loss.
	For foreign subsidiaries where the functional currency is the U.S. dollar, monetary assets and liabilities are translated into U.S. dollars at the current exchange rate on the balance sheet date. Nonmonetary assets and liabilities are remeasured into U.S. dollars at historical exchange rates. Revenue and expense items are translated at average rates of exchange prevailing during each period.
	Realized and unrealized foreign currency gains and losses arising from transactions denominated in currencies other than the subsidiary's functional currency are reflected in earnings with the exception of intercompany transactions considered to be of a long-term investment nature.
Inventory	Inventory
	Inventory is recorded at the lower of cost or market value using the first-in, first-out convention. The Company reduces the carrying value of inventory for those items that are potentially excess, obsolete or slow-moving based on changes in customer demand, technology developments or other economic factors.
	Sonus writes down evaluation equipment at the time of shipment to its customers, as it is probable that the inventory value will not be realized.
	Deferred product costs represent deferred cost of revenue for product shipments to customers prior to satisfaction of Sonus' revenue recognition criteria. Such costs are classified as inventory if the related deferred revenue is initially classified as current. Deferred product costs are recorded in Other assets if the related deferred revenue is initially classified as long-term, and remain a component of noncurrent assets until such costs are recognized in the consolidated statement of operations.
Property and Equipment	Property and Equipment
	Property and equipment are stated at cost, net of accumulated depreciation. Expenditures for maintenance and repairs are charged to expense as incurred. Depreciation is computed using the straight-line method over the estimated useful lives of the related assets, which range from two to five years. Leasehold improvements are amortized over the lesser of the lease term or five years. When an asset is sold or retired, the cost and related accumulated depreciation or amortization are eliminated, and the resulting gain or loss, if any, is recognized in income (loss) from operations in the consolidated statement of operations. The Company reviews property and equipment for impairment in the same manner as intangible assets discussed below.
	Software development costs associated with internal use software are incurred in three stages of development: the preliminary project stage, the application development stage and the post-implementation stage. Costs incurred during the preliminary project and post-implementation stages are expensed as incurred. Certain qualifying costs incurred during the application development stage are capitalized as property and equipment. Internal use software is amortized on a straight-line basis over its estimated useful life of three years, beginning when the software is ready for its intended use.
Intangible Assets and Goodwill	Intangible Assets and Goodwill
	Intangible assets are comprised of intellectual property purchased in 2010 which is amortized over its estimated useful life of five years; intangible assets arising from the August 24, 2012 acquisition of NET, comprised of developed technology, customer relationships, order backlog and internal use software, which are amortized over their estimated useful lives of four months to approximately six years; and intangible assets arising from the February 19, 2014 acquisition of PT, comprised of developed technology and customer relationships, which are amortized over their estimated useful lives of six to seven years. Intangible assets are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable based upon the estimated undiscounted cash flows. Recoverability of intangible assets with estimated lives and other long-lived assets is measured by a comparison of the carrying amount of an asset or asset group to future net undiscounted cash flows expected to be generated by the asset or asset group. If these comparisons indicate that an asset is not recoverable, the Company will recognize an impairment loss for the amount by which the carrying value of the asset or asset group exceeds the related estimated fair value. Estimated fair value is based on either discounted future operating cash flows or appraised values, depending on the nature of the asset. In the second quarter of 2013, the Company recorded an impairment charge of $0.6 million to write down the carrying value of one of its intellectual property intangible assets to zero. See Note 9 for additional information regarding this expense.
	Goodwill is recorded when the consideration for an acquisition exceeds the fair value of net tangible and identifiable intangible assets acquired. Goodwill is not amortized, but instead is tested for impairment at least annually or if indicators of potential impairment exist by comparing the fair value of the Company's reporting unit to its carrying value.
	The Company adopted ASU 2011-08, Intangibles - Goodwill and Other (Topic 350): Testing Goodwill for Impairment ("ASU 2011-08") in fiscal year 2013. ASU 2011-08 permits an entity to first perform a qualitative assessment to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying value. This qualitative assessment included the review of macroeconomic conditions, industry and market considerations, cost factors, overall company financial performance and other related facts and circumstances that could indicate that a more detailed assessment would be required. If it is concluded that it is more likely than not that the fair value is less than the carrying value, then it is necessary to perform the currently prescribed two-step goodwill impairment test. Alternatively, if it is concluded that it is not more likely than not that the fair value exceeds carrying value, the currently prescribed two-step goodwill impairment test is not required.
	The Company's annual testing for impairment of goodwill is completed as of November 30 of each year. The Company operates as a single operating segment with one reporting unit and consequently evaluates goodwill for impairment based on an evaluation of the fair value of the Company as a whole. The Company performed its qualitative assessments for both 2014 and 2013 and concluded each year that it was not more likely than not that the fair value of our reporting unit was less than its carrying value. The Company's testing for 2012 also indicated that no impairment of goodwill existed.
Share-Based Compensation	Stock-Based Compensation
	The Company's stock-based compensation cost is measured at the grant date based on the fair value of the award and is recognized as expense over the requisite service period, which generally represents the vesting period, and includes an estimate of the awards that will be forfeited. The Company uses the Black-Scholes valuation model for estimating the fair value on the date of grant of stock options. The fair value of stock option awards is affected by the Company's stock price as well as valuation assumptions, including the volatility of Sonus' stock price, expected term of the option, risk-free interest rate and expected dividends.
Research and Development Costs	Research and Development Costs
	Research and development costs are expensed as incurred.
Software Development Costs	Software Development Costs
	The costs for the development of new software and substantial enhancements to existing software are expensed as incurred until technological feasibility has been established, at which time any additional costs would be capitalized until the product is available for general release. The Company has determined that technological feasibility is established at the time a working model of the software is completed. The Company's process for developing software is essentially completed concurrently with the establishment of technological feasibility. Accordingly, no costs have been capitalized to date.
Advertising Costs	Advertising Costs
	Advertising costs are expensed as incurred.
Operating Segments	Operating Segments
	The Company operates in a single segment. Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker in making decisions regarding resource allocation and assessing performance. To date, the chief operating decision maker has made such decisions and assessed performance at the company level, as one segment. The Company's chief operating decision maker is its President and Chief Executive Officer.
Loss Contingencies and Reserves	Loss Contingencies and Reserves
	Loss Contingencies. Sonus is subject to ongoing business risks arising in the ordinary course of business that affect the estimation process of the carrying value of assets, the recording of liabilities and the possibility of various loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred or an asset has been impaired and the amount of loss can be reasonably estimated. Sonus regularly evaluates current information available to determine whether such amounts should be adjusted and records changes in estimates in the period they become known.
	Allowance for Doubtful Accounts. Sonus establishes billing terms at the time it negotiates purchase agreements with its customers. Sonus monitors its outstanding receivables for timely payments and potential collection issues. An allowance for doubtful accounts is estimated based on Sonus' assessment of the collectability of specific customer accounts.
	Accrual for Royalties. Sonus accrues for royalties for technology that it licenses from vendors based on established royalty rates and usage. In certain cases, Sonus has been contacted by third parties who claim that Sonus' products infringe on certain intellectual property of the third party. Sonus evaluates these claims and accrues amounts only when it is probable that the obligation has been incurred and the amounts are reasonably estimable.
	Reserve for Litigation and Legal Fees. Sonus is subject to various legal claims. Sonus reserves for legal contingencies and legal fees when it is probable that a loss has been incurred and the amounts are reasonably estimable.
Accounting for Income Taxes	Accounting for Income Taxes
	Deferred tax assets and liabilities are recognized for the expected future consequences of events that have been reflected in the consolidated financial statements. Deferred tax assets and liabilities are determined based on the differences between the book and tax bases of assets and liabilities and operating loss carryforwards, using tax rates expected to be in effect for the years in which the differences are expected to reverse. Such differences arise primarily from stock-based compensation, depreciation, accruals and reserves, acquired intangible assets, deferred revenue, tax credits, net operating loss carryforwards and allowances for accounts receivable. Sonus records valuation allowances to reduce deferred income tax assets to the amount that is more likely than not to be realized.
	Sonus has not provided for U.S. income taxes on the undistributed earnings of non-U.S. subsidiaries, as the Company plans to permanently reinvest these amounts. Cumulative undistributed foreign earnings were approximately $28 million at December 31, 2014 and approximately $17 million at December 31, 2013. Generally, the undistributed foreign earnings become subject to U.S. taxation upon the remittance of dividends and under certain other circumstances. The Company has been taxed on certain earnings of its non-U.S. subsidiaries. Previously taxed earnings were approximately $15 million at December 31, 2014 and $11 million at December 31, 2013. Thus, $13 million of the undistributed earnings at December 31, 2014 and $6 million at December 31, 2013 are subject to U.S. income taxes on undistributed earnings. The Company does not believe it is practicable to estimate with reasonable accuracy the hypothetical amount of the unrecognized deferred tax liability on its undistributed foreign earnings given the large number of tax jurisdictions involved and the many factors and assumptions required to estimate the amount of the U.S. federal income tax on the undistributed earnings after reduction for the available foreign tax credits.
	The Company determines whether it is more likely than not that a tax position will be sustained upon examination. If it is not more likely than not that a position will be sustained, no amount of the benefit attributable to the position is recognized. The tax benefit to be recognized of any tax position that meets the more likely than not recognition threshold is calculated as the largest amount that is more than 50% likely of being realized upon resolution of the contingency. The Company accounts for interest and penalties related to uncertain tax positions as part of its provision for income taxes.
	In September 2013, the U.S. Department of the Treasury and the Internal Revenue Service released final regulations relating to guidance on applying tax rules to amounts paid to acquire, produce or improve tangible personal property as well as rules for materials and supplies effective for tax years beginning on or after January 1, 2014. The Company has reviewed the regulations and has determined that its current method of accounting is appropriate under the regulations with no change required.
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern ("ASU 2014-15"). ASU 2014-15 provides guidelines determining when and how to disclose going concern uncertainties in the financial statements. The new standard requires management to perform interim and annual assessments of an entity's ability to continue as a going concern within one year of the date the financial statements are issued. An entity must provide certain disclosures if conditions or events raise substantial doubt about the entity's ability to continue as a going concern. AS 2014-15 applies to all entities and is effective for annual periods ending after December 15, 2016, and interim periods thereafter, with early adoption permitted. The adoption of ASU 2014-15 is not expected to have a material impact on the Company's consolidated financial statements.
	In June 2014, the FASB issued ASU 2014-12, Compensation - Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period (a consensus of the FASB Emerging Issues Task Force) (“ASU 2014-12”). ASU 2014-12 clarifies that entities should treat performance targets that can be met after the requisite service period of a share-based payment award as performance conditions that affect vesting. Therefore, an entity would not record compensation expense (measured as of the grant date without taking into account the effect of the performance target) related to an award for which transfer to the employee is contingent upon the entity’s satisfaction of a performance target until it becomes probable that the performance target will be met. ASU 2014-12 does not contain any new disclosure requirements. ASU 2014-12 is effective for the Company on January 1, 2015. The Company does not expect the adoption of ASU 2014-12 to have a material impact on its consolidated financial statements.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”) its final standard on revenue from contracts with customers. ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. The core principle of the revenue model is that an entity recognizes 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. In applying the revenue model to contracts within its scope, an entity identifies the contract(s) with a customer, identifies the performance obligations in the contract, determines the transaction price, allocates the transaction price to the performance obligations in the contract and recognizes revenue when (or as) the entity satisfies a performance obligation. ASU 2014-09 applies to all contracts with customers that are within the scope of other topics in the FASB Accounting Standards Codification ("ASC"). Certain of ASU 2014-09’s provisions also apply to transfers of nonfinancial assets, including in-substance nonfinancial assets that are not an output of an entity’s ordinary activities (i.e., property plant and equipment; real estate; or intangible assets). Existing accounting guidance applicable to these transfers has been amended or superseded. ASU 2014-09 also requires significantly expanded disclosures about revenue recognition. ASU 2014-09 is effective for the Company on January 1, 2017. The Company is currently assessing the potential impact of the adoption of ASU 2014-09 on its condensed consolidated financial statements.
	In April 2014, the FASB issued ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (“ASU 2014-08”), which amends the definition of discontinued operations in ASC 205-20 and requires entities to provide additional disclosures about discontinued operations as well as disposal transactions that do not meet the discontinued operations criteria. The new guidance eliminates the previous criteria that the operations and cash flows of the component that have been (or will be) eliminated from the ongoing operations of the entity as a result of the disposal transaction. The new guidance also eliminates the previous criteria that the entity will not have any significant continuing involvement in the operations of the component after the disposal transaction. Instead, ASU 2014-08 requires discontinued operations treatment for disposals of a component or group of components that represents a strategic shift that has or will have a major impact on an entity’s operations or financial results. ASU 2014-08 requires entities to reclassify assets and liabilities of a discontinued operation for all comparative periods presented in the statement of financial position. In addition, ASU 2014-08 requires that an entity disclose in its statement of cash flows, for all periods presented, either: (1) operating and investing cash flows or (2) depreciation and amortization, capital expenditures and significant operating and investing non-cash items related to the discontinued operation. ASU 2014-08 is effective prospectively for all disposals (except disposals classified as held for sale before the adoption date) or components initially classified as held for sale in periods beginning on or after December 15, 2014. The Company does not expect the adoption of ASU 2014-08 to have a material impact on its consolidated financial statements.
	In July 2013, the FASB issued ASU 2013-11, Presentation of a Liability for an Unrecognized Tax Benefit When a Net Operating Loss Carryforward or Tax Credit Carryforward Exists ("ASU 2013-11"), which provides guidance on financial statement presentation of an unrecognized tax benefit when a net operating loss ("NOL") carryforward, a similar tax loss or a tax credit carryforward exists. The FASB's objective in issuing ASU 2013-11 was to eliminate diversity in practice resulting from a lack of guidance on this topic in current GAAP. ASU 2013-11 requires that an entity present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, in the financial statements as a reduction to a deferred tax asset for an NOL carryforward, a similar tax loss or a tax credit unless certain conditions exist. ASU 2013-11 was effective for the Company beginning January 1, 2014. The adoption of ASU 2013-11 did not have an impact on the Company's consolidated financial statements, as the Company already applied the methodology prescribed by ASU 2013-11.
	In March 2013, the FASB issued ASU 2013-05, Foreign Currency Matters (Topic 830) - Parent's Accounting for the Cumulative Translation Adjustment upon Derecognition of Certain Subsidiaries or Groups of Assets within a Foreign Entity or of an Investment in a Foreign Entity ("ASU 2013-05"), which indicates that the entire amount of a cumulative translation adjustment ("CTA") related to an entity's investment in a foreign entity should be released when there has been either: (a) a sale of a subsidiary or group of net assets within a foreign entity and the sale represents the substantially complete liquidation of the investment in a foreign entity; (b) the loss of a controlling financial interest in an investment in a foreign entity (i.e., the foreign entity is deconsolidated); or (c) the step acquisition of a foreign entity (i.e., when the accounting for an entity has changed from applying the equity method for an investment in a foreign entity to consolidating the foreign entity). ASU 2013-05 does not change the requirement to release a pro rata portion of the CTA of the foreign entity into earnings for a partial sale of an equity method investment in a foreign entity. ASU 2013-05 was effective for the Company beginning January 1, 2014. The adoption of ASU 2013-05 did not have a material impact on the Company's consolidated financial statements.

BASIS_OF_PRESENTATION_AND_SUMM2

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Foreign currency translation	The components of foreign currency translation gains (losses), which are reported as a component of General and administrative expenses in the consolidated statements of operations, for the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
		Year ended December 31,
		2014			2013			2012
	Transaction losses	$	(420	)	$	(746	)	$	(1,365	)
	Remeasurement gains (losses)	1,980			(164		)	767
		$	1,560		$	(910	)	$	(598	)

BUSINESS_ACQUISITONS_Tables

BUSINESS ACQUISITONS (Tables)	12 Months Ended
	Dec. 31, 2014
Business Acquisition [Line Items]
Schedule of identifiable intangible assets as of the NET Acquisition Date	The identifiable intangible assets recorded in connection with the NET acquisition are as follows (in thousands):
	Developed technology	$	9,080
	Customer relationships	6,140
	Order backlog	860
	Internal use software	730
		$	16,810
Schedule of components of acquisition-related costs included in results of operations	The components of acquisition-related costs incurred in the years ended December 31, 2014, 2013 and 2012 are as follows (in thousands):
		Year ended December 31,
		2014			2013		2012
	Professional and services fees	$	1,309		$	93	$	3,571
	Change of control agreements	249			—		1,925
		$	1,558		$	93	$	5,496
PT [Member]
Business Acquisition [Line Items]
Summary of preliminary allocation of the purchase consideration	A summary of the allocation of the purchase consideration for PT is as follows (in thousands):
	Fair value of consideration transferred:
	Cash, net of cash acquired	$	35,022
	Fair value of equity awards assumed (see Note 16)	1,671
	Fair value of total consideration	$	36,693
	Fair value of assets acquired and liabilities assumed:
	Marketable securities	$	2,315
	Other current assets	9,337
	Property and equipment	2,251
	Intangible assets	17,100
	Goodwill	8,781
	Current liabilities	(2,762		)
	Other long-term liabilities	(329		)
		$	36,693
Schedule of identifiable intangible assets as of the NET Acquisition Date	The identifiable intangible assets recorded in connection with the PT acquisition are as follows (in thousands):
	Developed technology	$	13,200
	Customer relationships	3,900
		$	17,100
NET [Member]
Business Acquisition [Line Items]
Summary of preliminary allocation of the purchase consideration	A summary of the allocation of the purchase consideration for NET is as follows (in thousands):
	Fair value of consideration transferred:
	Cash, net of cash acquired	$	35,508
	Fair value of equity awards assumed (see Note 16)	892
	Fair value of total consideration	$	36,400
	Fair value of assets acquired and liabilities assumed:
	Marketable securities	$	5,359
	Deferred income taxes	681
	Other current assets	13,388
	Property and equipment	4,694
	Noncurrent investments	10,167
	Intangible assets	16,810
	Goodwill	27,317
	Other noncurrent assets	1,843
	Current liabilities	(9,350		)
	Debt	(34,208		)
	Other long-term liabilities	(301		)
		$	36,400
Schedule of unaudited pro forma results of operations	Accordingly, these unaudited pro forma results are presented for illustrative purposes and are not intended to represent or be indicative of the actual results of operations of the combined company that would have been achieved had the acquisition occurred at the beginning of the period presented, nor are they intended to represent or be indicative of future results of operations (in thousands, except per share amounts):
		Year ended
		December 31,
		2012
	Revenue	$	284,970
	Net loss	$	(62,148	)
	Loss per share	$	(1.11	)

EARNINGS_LOSS_PER_SHARE_Tables

EARNINGS (LOSS) PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Schedule of calculations of shares used to compute basic and diluted earnings (loss) per share	The calculations of shares used to compute basic and diluted loss per share are as follows (in thousands):
		Year ended December 31,
		2014	2013	2012
	Weighted average shares outstanding—basic	50,245	55,686	56,018
	Potential dilutive common shares	—	—	—
	Weighted average shares outstanding—diluted	50,245	55,686	56,018

CASH_EQUIVALENTS_AND_INVESTMEN1

CASH EQUIVALENTS AND INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2014
Investments, All Other Investments [Abstract]
Schedule of amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments	The amortized cost, gross unrealized gains and losses and fair value of the Company's cash equivalents and investments at December 31, 2014 and 2013 were comprised of the following (in thousands):
		31-Dec-14
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	11,653	$	—	$	—		$	11,653
	Short-term investments
	Municipal obligations	$	1,273	$	1	$	(1	)	$	1,273
	U.S. government agency notes	4,016		—		—			4,016
	Corporate debt securities	40,921		2		(59		)	40,864
	Commercial paper	9,340		—		—			9,340
	Certificates of deposit	8,950		—		—			8,950
		$	64,500	$	3	$	(60	)	$	64,443
	Investments
	Municipal obligations	$	2,702	$	1	$	(3	)	$	2,700
	U.S. government agency notes	2,300		—		(1		)	2,299
	Corporate debt securities	35,897		4		(86		)	35,815
	Commercial paper	1,093		—		—			1,093
	Certificates of deposit	500		—		—			500
		$	42,492	$	5	$	(90	)	$	42,407
		31-Dec-13
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	50,404	$	—	$	—		$	50,404
	Short-term investments
	U.S. government agency notes	$	47,895	$	15	$	—		$	47,910
	Corporate debt securities	81,993		35		(8		)	82,020
	Commercial paper	5,647		2		—			5,649
	Certificates of deposit	3,300		3		—			3,303
		$	138,835	$	55	$	(8	)	$	138,882
	Investments
	U.S. government agency notes	$	9,254	$	3	$	—		$	9,257
	Foreign government notes	1,250		—		—			1,250
	Corporate debt securities	23,848		17		(8		)	23,857
		$	34,352	$	20	$	(8	)	$	34,364
Schedule of fair value of financial assets	The following table shows the fair value of the Company's financial assets at December 31, 2014 and 2013. These financial assets are comprised of the Company's available-for-sale debt securities and reported under the captions Cash and cash equivalents, Short-term investments and Investments in the consolidated balance sheets (in thousands):
				Fair value measurements at
				December 31, 2014 using:
		Total carrying		Quoted prices		Significant other			Significant
		value at		in active		observable			unobservable
		December 31,		markets		inputs			inputs
		2014		(Level 1)		(Level 2)			(Level 3)
	Cash equivalents	$	11,653	$	11,653	$	—		$	—
	Short-term investments
	Municipal obligations	$	1,273	$	—	$	1,273		$	—
	U.S. government agency notes	4,016		—		4,016			—
	Corporate debt securities	40,864		—		40,864			—
	Commercial paper	9,340		—		9,340			—
	Certificates of deposit	8,950		—		8,950			—
		$	64,443	$	—	$	64,443		$	—
	Investments
	Municipal obligations	$	2,700	$	—	$	2,700		$	—
	U.S. government agency notes	2,299		—		2,299			—
	Corporate debt securities	35,815		—		35,815			—
	Commercial paper	1,093		—		1,093			—
	Certificates of deposit	500		—		500			—
		$	42,407	$	—	$	42,407		$	—
				Fair value measurements at
				December 31, 2013 using:
		Total carrying		Quoted prices		Significant other			Significant
		value at		in active		observable			unobservable
		December 31,		markets		inputs			inputs
		2013		(Level 1)		(Level 2)			(Level 3)
	Cash equivalents	$	50,404	$	50,404	$	—		$	—
	Short-term investments
	U.S. government agency notes	$	47,910	$	—	$	47,910		$	—
	Corporate debt securities	82,020		—		82,020			—
	Commercial paper	5,649		—		5,649			—
	Certificates of deposit	3,303		—		3,303			—
		$	138,882	$	—	$	138,882		$	—
	Investments
	U.S. government agency notes	$	9,257	$	—	$	9,257		$	—
	Foreign government notes	1,250		—		1,250			—
	Corporate debt securities	23,857		—		23,857			—
		$	34,364	$	—	$	34,364		$	—

ACCOUNTS_RECEIVABLE_NET_Tables

ACCOUNTS RECEIVABLE, NET (Tables)	12 Months Ended
	Dec. 31, 2014
Receivables [Abstract]
Schedule of accounts receivable, net	Accounts receivable, net, consist of the following (in thousands):
		December 31,
		2014			2013
	Accounts receivable, gross	$	63,001		$	64,620
	Allowance for doubtful accounts	(58		)	(157		)
	Accounts receivable, net	$	62,943		$	64,463
Schedule of allowance for doubtful accounts	The activity in the Company's allowance for doubtful accounts is as follows (in thousands):
	Year ended December 31,	Balance at			Charges			Write-offs			Balance at
		beginning			to expense						end of
		of year									year
	2014	$	157		$	92		$	(191	)	$	58
	2013	$	—		$	415		$	(258	)	$	157
	2012	$	—		$	—		$	—		$	—

INVENTORY_Tables

INVENTORY (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Schedule of inventory	Inventory consists of the following (in thousands):
		December 31,
		2014			2013
	On-hand final assemblies and finished goods inventories	$	19,285		$	19,070
	Deferred cost of goods sold	2,829			4,387
		22,114			23,457
	Less current portion	(22,114		)	(21,793		)
	Noncurrent portion (included in Other assets)	$	—		$	1,664

PROPERTY_AND_EQUIPMENT_Tables

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	Property and equipment under capital leases included in the amounts above are as follows (in thousands):
		December 31,
		2014				2013
	Cost	$	113			$	326
	Less accumulated depreciation	(71		)		(220		)
	Property and equipment under capital leases, net	$	42			$	106
	The net book values of the Company's property and equipment by geographic area are as follows (in thousands):
		December 31,
		2014				2013
	United States	$	12,652			$	13,960
	Asia/Pacific	3,574				4,665
	Europe	765				453
	Other	854				24
		$	17,845			$	19,102
	Property and equipment consists of the following (in thousands):
				December 31,
		Useful Life		2014				2013
	Equipment	3 years		$	65,703			$	80,710
	Software	2-3 years		17,342				15,410
	Furniture and fixtures	3-5 years		612				855
	Leasehold improvements	Shorter of the life of the lease or estimated useful life (1-5 years)		11,920				10,659
				95,577				107,634
	Less accumulated depreciation and amortization			(77,732		)		(88,532		)
	Property and equipment, net			$	17,845			$	19,102

INTANGIBLE_ASSETS_AND_GOODWILL1

INTANGIBLE ASSETS AND GOODWILL (Tables)	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of intangible assets	The Company's intangible assets at December 31, 2014 and 2013 consist of the following (in thousands):
	31-Dec-14	Weighted average amortization period		Cost				Accumulated				Net
		(years)						amortization				carrying value
	Intellectual property	5		$	999			$	999			$	—
	Developed technology	6.18		22,280				5,193				17,087
	Customer relationships	5.57		10,040				4,695				5,345
	Internal use software	3		730				568				162
		5.75		$	34,049			$	11,455			$	22,594
	31-Dec-13	Weighted average amortization period		Cost				Accumulated				Net
		(years)						amortization				carrying value
	Intellectual property	5		$	999			$	999			$	—
	Developed technology	5.03		9,080				2,729				6,351
	Customer relationships	5.3		6,140				2,806				3,334
	Internal use software	3		730				324				406
		4.35		$	16,949			$	6,858			$	10,091
Schedule of amortization expense related to intangible assets	Amortization expense for intangible assets for the years ended December 31, 2014, 2013 and 2012 was as follows (in thousands):
		Year ended December 31,												Statement of operations classification
		2014				2013				2012
	Intellectual property	$	—			$	200			$	400			Research and development
	Developed technology	2,464				1,999				730				Cost of revenue - product
	Customer relationships	1,889				2,104				702				Sales and marketing
	Order backlog	—				—				860				Cost of revenue - product
	Internal use software	244				243				81				Cost of revenue - product
		$	4,597			$	4,546			$	2,773
Schedule of estimated future amortization expense for intangible assets	Estimated future amortization expense for the Company's intangible assets at December 31, 2014 is as follows (in thousands):
	Years ending December 31,
	2015	$	5,646
	2016	5,290
	2017	5,259
	2018	2,953
	2019	2,263
	Thereafter	1,183
		$	22,594
Schedule of goodwill	The changes in the carrying value of the Company's goodwill in the years ended December 31, 2014 and 2013 are as follows (in thousands):
		Year ended December 31,
		2014				2013
	Balance at January 1
	Goodwill	$	35,485			$	35,485
	Accumulated impairment losses	(3,106		)		(3,106		)
		32,379				32,379
	Acquisition of PT	8,781				—
	Sale of MPS business	(1,897		)		—
	Balance at December 31	$	39,263			$	32,379
	The components of the Company's goodwill balances at December 31, 2014 and 2013 are as follows:
		December 31,
		2014				2013
	Balance
	Goodwill	$	42,369			$	35,485
	Accumulated impairment losses	(3,106		)		(3,106		)
		$	39,263			$	32,379

ACCRUED_EXPENSES_Tables

ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2014
Payables and Accruals [Abstract]
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands):
		December 31,
		2014		2013
	Employee compensation and related costs	$	20,042	$	20,683
	Other	12,107		13,343
		$	32,149	$	34,026

RESTRUCTURING_ACCRUAL_Tables

RESTRUCTURING ACCRUAL (Tables)	12 Months Ended
	Dec. 31, 2014
Restructuring and Related Activities [Abstract]
Summary of restructuring accrual activity	The tables below summarize the restructuring accrual activity for the years ended December 31, 2014 and 2013 (in thousands):
		Balance at		Initiatives		Cash			Balance at
		January 1,		charged to		payments			December 31,
		2014		expense					2014
	Severance	$	1,333	$	3,615	$	(3,266	)	$	1,682
	Facilities	3,012		1,820		(1,180		)	3,652
		$	4,345	5,435		$	(4,446	)	$	5,334
	Asset write-offs			190
				$	5,625
		Balance at		Initiatives		Cash			Balance at
		January 1,		charged to		payments			December 31,
		2013		expense					2013
	Severance	$	1,135	$	5,102	$	(4,904	)	$	1,333
	Facilities	4,100		309		(1,397		)	3,012
		$	5,235	$	5,411	$	(6,301	)	$	4,345

LONGTERM_LIABILITIES_Tables

LONG-TERM LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2014
Other Liabilities [Abstract]
Schedule of long-term liabilities	Long-term liabilities consist of the following (in thousands):
		December 31,
		2014			2013
	Capital lease obligations	$	70		$	154
	Deferred rent	3,160			3,057
	Restructuring	5,334			4,345
	Other	1,125			—
		9,689			7,556
	Current portion *	(4,443		)	(3,185		)
	Long-term liabilities, net of current portion	$	5,246		$	4,371
	* Includes $3.4 million at December 31, 2014 and $2.5 million at December 31, 2013 of current accrued restructuring reported as a component of Accrued expenses in the consolidated balance sheets.

STOCKBASED_COMPENSATION_PLANS_

STOCK-BASED COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of activity related to outstanding stock options	The activity related to the Company's outstanding stock options during the year ended December 31, 2014 is as follows:
		Number of			Weighted			Weighted		Aggregate
		Shares			Average			Average		Intrinsic Value
					Exercise Price			Remaining		(in thousands)
								Contractual Term
								(years)
	Outstanding at January 1, 2014	6,627,137			$	16.11
	Granted	2,331,174			$	17.97
	PT outstanding options converted to Sonus options	256,548			$	8.65
	Exercised	(806,385	)		$	12.64
	Forfeited	(548,826	)		$	14.66
	Expired	(338,216	)		$	25.89
	Outstanding at December 31, 2014	7,521,432			$	16.47		6.91		$	31,319
	Vested or expected to vest at December 31, 2014	6,985,686			$	16.47		6.77		$	29,528
	Exercisable at December 31, 2014	3,651,057			$	16.86		5.14		$	16,809
Schedule of assumptions used to estimate the fair value of options at the date of grant using the Black-Scholes option pricing model	The grant date fair values of options to purchase common stock granted in the years ended December 31, 2014, 2013 and 2012 were estimated using the Black-Scholes valuation model with the following assumptions:
		Year ended December 31,
		2014		2013		2012
	Risk-free interest rate	1.53%-2.70%		0.82%-1.71%		0.67%-0.89%
	Expected dividends	—		—		—
	Weighted average volatility	60.80%		63.20%		67.40%
	Expected life (years)	4.5-6.0		4.5-6.0		4.5
Schedule of activity related to unvested restricted stock grants	The activity related to the Company's unvested restricted stock grants for the year ended December 31, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
	Unvested balance at January 1, 2014	247,747			$	14.08
	Granted	553,609			$	17.03
	Vested	(428,674	)		$	15.63
	Forfeited	(2,500	)		$	7
	Unvested balance at December 31, 2014	370,182			$	16.74
Schedule of activity related to performance stock awards	The activity related to the Company's performance-based stock awards for the year ended December 31, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
	Unvested balance at January 1, 2014	211,906			$	12.98
	Granted	—			$	—
	Vested	(136,526	)		$	12.63
	Forfeited	(41,145	)		$	13.6
	Unvested balance at December 31, 2014	34,235			$	13.6
Schedule of stock-based compensation expenses which are included in condensed consolidated statement of operations	The consolidated statements of operations include stock-based compensation for the years ended December 31, 2014, 2013 and 2012 as follows (in thousands):
		Year ended December 31,
		2014				2013			2012
	Product cost of revenue	$	337			$	181		$	162
	Service cost of revenue	1,449				1,050			813
	Research and development	5,759				3,616			2,297
	Sales and marketing	5,437				4,780			2,006
	General and administrative	10,932				8,246			3,725
		$	23,914			$	17,873		$	9,003
Schedule of common stock reserved for future issuance	Common stock reserved for future issuance at December 31, 2014 consists of the following:
	Amended 2007 Plan	3,446,366
	ESPP	2,139,824
		5,586,190

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Income (Loss) Before Taxes	The components of income (loss) from continuing operations before income taxes consist of the following (in thousands):
		Year ended December 31,
		2014				2013				2012
	Loss before income taxes:
	United States	$	(16,582	)		$	(21,076	)		$	(49,337	)
	Foreign	1,941				409				1,609
		$	(14,641	)		$	(20,667	)		$	(47,728	)
Schedule of Income Tax Expense (Benefit)	The provision (benefit) for income taxes from continuing operations consists of the following (in thousands):
		Year ended December 31,
		2014				2013				2012
	Provision (benefit) for income taxes:
	Current:
	Federal	$	23			$	14			$	14
	State	150				150				105
	Foreign	926				1,696				1,465
	Total current	1,099				1,860				1,584
	Deferred:
	Federal	(3,885		)		(1,911		)		(12,441		)
	State	(1,656		)		(103		)		(1,680		)
	Foreign	414				(1,081		)		607
	Change in valuation allowance	6,242				2,687				14,371
	Total deferred	1,115				(408		)		857
	Total	$	2,214			$	1,452			$	2,441
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the Company's effective tax rate for continuing operations to the statutory federal rate is as follows:
		Year ended December 31,
		2014			2013			2012
	U.S. statutory income tax rate	(35.0	)%		(35.0	)%		(35.0	)%
	State income taxes, net of federal benefit	(4.9	)		0.4			(3.6	)
	Foreign income taxes	5.1			1.3			3.2
	Capital loss expiration	—			24			—
	Foreign deemed dividends	11.5			1.8			2.1
	Stock-based compensation	12			7.6			3.4
	Tax credits	(14.6	)		(6.1	)		(0.7	)
	Deferred cost of goods sold elimination	—			—			(1.2	)
	Valuation allowance	29.8			9.9			35.5
	Goodwill amortization	4.8			3.3			0.5
	Meals and entertainment	2.5			1.3			0.7
	Tax gain on sale of acquired assets	4.2			—			—
	Other, net	(0.3	)		(1.5	)		0.2
	Effective income tax rate	15.1	%		7	%		5.1	%
Summary of Deferred Tax Assets and Liabilities	The following is a summary of the significant components of deferred income tax assets and liabilities (in thousands):
		December 31,
		2014				2013
	Assets:
	Net operating loss carryforwards	$	74,717			$	64,811
	Research and development tax credits	24,978				21,401
	Other tax credits	91				160
	Intangible assets	4,808				2,530
	Deferred revenue	1,911				4,143
	Accrued expenses	10,619				10,519
	Inventory	5,713				6,498
	Stock-based compensation	12,913				9,263
	Other temporary differences	3,924				3,642
		139,674				122,967
	Valuation allowance	(137,640		)		(119,616		)
	Total deferred tax assets	2,034				3,351
	Liabilities:
	Purchased intangible assets	(1,623		)		(922		)
	Unrealized gain on available-for-sale securities	—				(574		)
	Total deferred tax liabilities	(1,623		)		(1,496		)
	Total net deferred tax assets	$	411			$	1,855
	Reported as:
	Deferred income taxes - current assets	$	991			$	656
	Deferred income taxes - noncurrent assets	1,043				—
	Deferred income taxes - noncurrent liabilities	(1,623		)		1,199
		$	411			$	1,855
Schedule of Unrecognized Tax Benefits	A reconciliation of the Company's unrecognized tax benefits is as follows (in thousands):
		2014				2013				2012
	Unrecognized tax benefits at January 1	$	8,861			$	8,847			$	10,004
	Increases related to current year tax positions	14				14				14
	Decreases related to prior period tax positions	—				—				(1,171		)
	Unrecognized tax benefits at December 31	$	8,875			$	8,861			$	8,847

MAJOR_CUSTOMERS_Tables

MAJOR CUSTOMERS (Tables)	12 Months Ended
	Dec. 31, 2014
Risks and Uncertainties [Abstract]
Schedule of customers contributing 10% or more of the revenue	The following customer contributed 10% or more of the Company's revenue in each of the years ended December 31, 2014, 2013 and 2012:
		Year ended December 31,
		2014	2013	2012
	AT&T	19%	15%	20%

GEOGRAPHIC_AND_OPERATING_SEGME1

GEOGRAPHIC AND OPERATING SEGMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Summary of revenue by geographic area as a percentage of total revenue	The Company's classification of revenue by geographic area is determined by the location of the Company's customers. The following table summarizes revenue by geographic area as a percentage of total revenue:
		Year ended December 31,
		2014		2013			2012
	United States	71	%	69	%		68	%
	Europe, Middle East and Africa	13		12			13
	Japan	9		12			14
	Other Asia Pacific	5		5			4
	Other	2		2			1
		100	%	100	%		100	%
Schedule of revenue by type	The Company's service revenue is comprised of the following (in thousands):
		Year ended December 31,
		2014			2013				2012
	Maintenance	$	90,003		$	84,698			$	76,423
	Professional services	23,868			24,763				24,385
		$	113,871		$	109,461			$	100,808

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	Future minimum payments under operating lease arrangements as of December 31, 2014 are as follows (in thousands):
	Years ending December 31,
	2015	$	6,330
	2016	5,506
	2017	3,855
	2018	2,929
	2019	1,351
	Thereafter	38
		$	20,009

QUARTERLY_RESULTS_UNAUDITED_Ta

QUARTERLY RESULTS (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	The following tables present the Company's quarterly operating results for the years ended December 31, 2014 and 2013. The information for each of these quarters is unaudited and has been prepared on the same basis as the audited consolidated financial statements. In the opinion of management, all necessary adjustments, consisting only of normal recurring adjustments, have been included to present fairly the unaudited consolidated quarterly results when read in conjunction with the Company's audited consolidated financial statements and related notes.
		First			Second			Third			Fourth
		Quarter (1)			Quarter			Quarter			Quarter
		(In thousands, except per share data)
	Fiscal 2014
	Revenue	$	70,742		$	75,570		$	73,216		$	76,798
	Cost of revenue	24,319			28,282			25,314			25,006
	Gross profit	$	46,423		$	47,288		$	47,902		$	51,792
	Loss from operations	$	(5,791	)	$	(4,801	)	$	(4,715	)	$	(1,945	)
	Net loss	$	(3,953	)	$	(5,497	)	$	(5,213	)	$	(2,192	)
	Loss per share (2):
	Basic	$	(0.07	)	$	(0.11	)	$	(0.11	)	$	(0.04	)
	Diluted	$	(0.07	)	$	(0.11	)	$	(0.11	)	$	(0.04	)
	Shares used in computing loss per share:
	Basic	53,080			49,424			49,291			49,361
	Diluted	53,080			49,424			49,291			49,361
		First			Second			Third			Fourth
		Quarter			Quarter			Quarter			Quarter
		(In thousands, except per share data)
	Fiscal 2013
	Revenue	$	63,288		$	69,193		$	68,099		$	76,153
	Cost of revenue	25,486			25,185			25,835			27,767
	Gross profit	$	37,802		$	44,008		$	42,264		$	48,386
	Loss from operations	$	(13,472	)	$	(4,633	)	$	(2,911	)	$	(59	)
	Net income (loss)	$	(13,748	)	$	(4,870	)	$	(3,773	)	$	272
	Income (loss) per share (2):
	Basic	$	(0.24	)	$	(0.09	)	$	(0.07	)	$	0.01
	Diluted	$	(0.24	)	$	(0.09	)	$	(0.07	)	$	—
	Shares used in computing income (loss) per share:
	Basic	56,308			56,478			55,855			54,188
	Diluted	56,308			56,478			55,855			54,699
	__________________________________
	-1	Includes the results of PT for the period subsequent to February 19, 2014.
	-2	Earnings (loss) per share is calculated independently for each of the quarters presented; accordingly, the sum of the quarterly earnings (loss) per share amounts may not equal the total calculated for the year.

BASIS_OF_PRESENTATION_AND_SUMM3

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) (USD $)	3 Months Ended	12 Months Ended			0 Months Ended
	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 30, 2015	Dec. 01, 2014
		segment	financial_institution
		financial_institution
Property, Plant and Equipment [Line Items]
Common stock, shares authorized		120,000,000	120,000,000			600,000,000
Common stock, par value (in dollars per share)		$0.00	$0.00
Maximum measurement period from the acquisition date within which company records adjustments to the assets acquired and liabilities assumed		1 year
Write-off of prepaid royalties for software licenses	$7,100,000	$0	$0	$7,083,000
Number of financial institutions		3	2
Advertising expense		1,500,000	2,700,000	1,100,000
Number of reportable operating segments		1
Undistributed earnings of foreign subsidiaries		28,000,000	17,000,000
Undistributed earnings of foreign subsidiaries previously taxed		15,000,000	11,000,000
Undistributed earnings of foreign subsidiaries subject to U.S. income taxes		$13,000,000	$6,000,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		5 years
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		3 years
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		2 years
Minimum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		1 year
Minimum [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		2 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		5 years
Maximum [Member] | Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		5 years
Maximum [Member] | Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		3 years
Subsequent Event [Member]
Property, Plant and Equipment [Line Items]
Stock split ratio					0.2

BASIS_OF_PRESENTATION_AND_SUMM4

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets and Goodwill (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	5 years 9 months 0 days	4 years 4 months 6 days
Impairment of intangible assets	$0	$600	$0
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	5 years	5 years
Minimum [Member] | Technology, Customers, Orders and Internal Software [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	4 months
Maximum [Member] | Technology, Customers, Orders and Internal Software [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible asset, useful life	6 years

BASIS_OF_PRESENTATION_AND_SUMM5

BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Foreign Currency Translation (Details) (General and Administrative Expense [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
General and Administrative Expense [Member]
Schedule of Foreign Currency Balance [Line Items]
Transaction losses	($420)	($746)	($1,365)
Remeasurement gains (losses)	1,980	-164	767
Transaction gains (losses)	$1,560	($910)	($598)

BUSINESS_ACQUISITONS_Sale_of_M

BUSINESS ACQUISITONS - Sale of MPS (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 20, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of business	$2,000,000	$0	$0
Multi Protocol Server [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture of business				2,000,000
Inventory				200,000
Fixed assets				100,000
Deferred revenue				200,000
Goodwill				1,900,000
Transaction costs				$400,000

BUSINESS_ACQUISITONS_Details

BUSINESS ACQUISITONS - (Details) (USD $)	12 Months Ended			0 Months Ended	10 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 19, 2014	Dec. 31, 2014	Aug. 24, 2012
Fair value of consideration transferred:
Cash, net of cash acquired	$35,022,000	$0	$35,508,000
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.	1,671,000	0	892,000
Allocation of the purchase consideration:
Goodwill	39,263,000	32,379,000	32,379,000		39,263,000
Acquisition-Related Costs
Professional Fees	1,309,000	93,000	3,571,000
Change of Control Agreements	249,000	0	1,925,000
Acquisition-related	1,558,000	93,000	5,496,000
PT [Member]
Acquisition Of Net
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 9 months 18 days
Cash consideration per share of the acquired entity (in dollars per share)				$3.75
Goodwill, Purchase Accounting Adjustments					600,000
Increase (decrease) to other current assets					-400,000
Increase (decrease) to other long-term liabilities					200,000
Revenue	14,600,000
Fair value of consideration transferred:
Cash, net of cash acquired				35,022,000
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.				1,671,000
Fair value of total consideration				36,693,000
Allocation of the purchase consideration:
Marketable securities				2,315,000
Other current assets				9,337,000
Property and equipment				2,251,000
Intangible assets				17,100,000
Goodwill				8,781,000
Current liabilities				-2,762,000
Other long-term liabilities				-329,000
Assets acquired and liabilities assumed				36,693,000
Acquisition-Related Costs
Acquisition-related	1,300,000
PT [Member] | Developed technology [Member]
Allocation of the purchase consideration:
Intangible assets				13,200,000
PT [Member] | Customer relationships [Member]
Allocation of the purchase consideration:
Intangible assets				3,900,000
NET [Member]
Acquisition Of Net
Cash consideration per share of the acquired entity (in dollars per share)						$1.35
Decrease to current liabilities			500,000
Cash consideration						41,500,000
Revenue			17,300,000
Net loss			9,500,000
Reduction to goodwill			1,400,000
Increase to other current assets			900,000
Period over which goodwill will be deductible for tax purpose	15 years
Fair value of consideration transferred:
Cash, net of cash acquired						35,508,000
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.						892,000
Fair value of total consideration						36,400,000
Allocation of the purchase consideration:
Marketable securities						5,359,000
Deferred income taxes						681,000
Other current assets						13,388,000
Property and equipment						4,694,000
Noncurrent investments						10,167,000
Intangible assets						16,810,000
Goodwill						27,317,000
Other non-current assets						1,843,000
Current liabilities						-9,350,000
Debt						-34,208,000
Other long-term liabilities						-301,000
Assets acquired and liabilities assumed						36,400,000
Unaudited pro forma results of operations
Revenue	284,970,000
Net loss	-62,148,000
Loss per share (in dollars per share)	($1.11)
NET [Member] | Developed technology [Member]
Allocation of the purchase consideration:
Intangible assets						9,080,000
NET [Member] | Customer relationships [Member]
Allocation of the purchase consideration:
Intangible assets						6,140,000
NET [Member] | Order backlog [Member]
Allocation of the purchase consideration:
Intangible assets						860,000
NET [Member] | Internal use software [Member]
Allocation of the purchase consideration:
Intangible assets						730,000
SDN Business [Member]
Acquisition-Related Costs
Acquisition-related	$300,000

EARNINGS_LOSS_PER_SHARE_Detail

EARNINGS (LOSS) PER SHARE - (Details)	3 Months Ended									12 Months Ended
	Dec. 31, 2014	Sep. 26, 2014	Jun. 27, 2014	Mar. 28, 2014		Dec. 31, 2013	Sep. 27, 2013	Jun. 28, 2013	Mar. 29, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of weighted average shares outstanding from basic to diluted
Weighted average shares outstanding - basic	49,361,000	49,291,000	49,424,000	53,080,000	[1]	54,188,000	55,855,000	56,478,000	56,308,000	50,245,000	55,686,000	56,018,000
Potential dilutive common shares										0	0	0
Weighted average shares outstanding - diluted	49,361,000	49,291,000	49,424,000	53,080,000	[1]	54,699,000	55,855,000	56,478,000	56,308,000	50,245,000	55,686,000	56,018,000
Common stock and unvested shares of restricted stock not included because their effect would have been antidilutive (in shares)										8,000,000	7,100,000	5,600,000
[1]	(1)Includes the results of PT for the period subsequent to February 19, 2014.

CASH_EQUIVALENTS_AND_INVESTMEN2

CASH EQUIVALENTS AND INVESTMENTS - Narrative (Details) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Proceeds from Sale of Available-for-sale Securities	$45,900,000
Available-for-sale Securities, Gross Realized Gains	$46,000

CASH_EQUIVALENTS_AND_INVESTMEN3

CASH EQUIVALENTS AND INVESTMENTS - Schedule of Activity for Short-Term Investments (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Cash equivalents, amortized cost	11,653	$50,404
Cash equivalents, fair value	11,653	50,404
Marketable securities, amortized cost	64,500	138,835
Marketable securities, unrealized gains	3	55
Marketable securities, unrealized losses	-60	-8
Marketable securities, fair value	64,443	138,882
Investments, amortized cost	42,492	34,352
Investments, unrealized gains	5	20
Investments, unrealized losses	-90	-8
Investments, fair value	42,407	34,364
Minimum [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Period considered to classify available-for-sale securities as investments	1 year
Maximum [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Period considered to classify available-for-sale securities as investments	2 years
Municipal obligations [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Marketable securities, amortized cost	1,273
Marketable securities, unrealized gains	1
Marketable securities, unrealized losses	-1
Marketable securities, fair value	1,273
Investments, amortized cost	2,702
Investments, unrealized gains	1
Investments, unrealized losses	-3
Investments, fair value	2,700
U.S. government agency notes [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Marketable securities, amortized cost	4,016	47,895
Marketable securities, unrealized gains	0	15
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	4,016	47,910
Investments, amortized cost	2,300	9,254
Investments, unrealized gains	0	3
Investments, unrealized losses	-1	0
Investments, fair value	2,299	9,257
Foreign government notes [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Investments, amortized cost		1,250
Investments, unrealized gains		0
Investments, unrealized losses		0
Investments, fair value		1,250
Corporate debt securities [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Marketable securities, amortized cost	40,921	81,993
Marketable securities, unrealized gains	2	35
Marketable securities, unrealized losses	-59	-8
Marketable securities, fair value	40,864	82,020
Investments, amortized cost	35,897	23,848
Investments, unrealized gains	4	17
Investments, unrealized losses	-86	-8
Investments, fair value	35,815	23,857
Commercial paper [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Marketable securities, amortized cost	9,340	5,647
Marketable securities, unrealized gains	0	2
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	9,340	5,649
Investments, amortized cost	1,093
Investments, unrealized gains	0
Investments, unrealized losses	0
Investments, fair value	1,093
Certificates of deposit [Member]
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments
Marketable securities, amortized cost	8,950	3,300
Marketable securities, unrealized gains	0	3
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	8,950	3,303
Investments, amortized cost	500
Investments, unrealized gains	0
Investments, unrealized losses	0
Investments, fair value	500

CASH_EQUIVALENTS_AND_INVESTMEN4

CASH EQUIVALENTS AND INVESTMENTS - Schedule of Short-Term Investments by Measurement (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Cash and cash equivalents, Marketable securities and Investments
Cash equivalents, fair value	$11,653	$50,404
Marketable securities, fair value	64,443	138,882
Investments, fair value	42,407	34,364
Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Cash equivalents, fair value	11,653	50,404
Marketable securities, fair value	64,443	138,882
Investments, fair value	42,407	34,364
Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Cash equivalents, fair value	11,653	50,404
Marketable securities, fair value	0	0
Investments, fair value	0	0
Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Cash equivalents, fair value	0	0
Marketable securities, fair value	64,443	138,882
Investments, fair value	42,407	34,364
Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Cash equivalents, fair value	0	0
Marketable securities, fair value	0	0
Investments, fair value	0	0
Municipal obligations [Member] | Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	1,273
Investments, fair value	2,700
Municipal obligations [Member] | Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0
Investments, fair value	0
Municipal obligations [Member] | Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	1,273
Investments, fair value	2,700
Municipal obligations [Member] | Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0
Investments, fair value	0
U.S. government agency notes [Member] | Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	4,016	47,910
Investments, fair value	2,299	9,257
U.S. government agency notes [Member] | Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0	0
U.S. government agency notes [Member] | Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	4,016	47,910
Investments, fair value	2,299	9,257
U.S. government agency notes [Member] | Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0	0
Foreign government notes [Member] | Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Investments, fair value		1,250
Foreign government notes [Member] | Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Investments, fair value		0
Foreign government notes [Member] | Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Investments, fair value		1,250
Foreign government notes [Member] | Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Investments, fair value		0
Corporate debt securities [Member] | Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	40,864	82,020
Investments, fair value	35,815	23,857
Corporate debt securities [Member] | Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0	0
Corporate debt securities [Member] | Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	40,864	82,020
Investments, fair value	35,815	23,857
Corporate debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0	0
Commercial paper [Member] | Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	9,340	5,649
Investments, fair value	1,093
Commercial paper [Member] | Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0
Commercial paper [Member] | Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	9,340	5,649
Investments, fair value	1,093
Commercial paper [Member] | Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0
Certificates of deposit [Member] | Total carrying value [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	8,950	3,303
Investments, fair value	500
Certificates of deposit [Member] | Quoted prices in active markets (Level 1) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	0
Certificates of deposit [Member] | Significant other observable inputs (Level 2) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	8,950	3,303
Investments, fair value	500
Certificates of deposit [Member] | Significant unobservable inputs (Level 3) [Member]
Cash and cash equivalents, Marketable securities and Investments
Marketable securities, fair value	0	0
Investments, fair value	$0

ACCOUNTS_RECEIVABLE_NET_Schedu

ACCOUNTS RECEIVABLE, NET - Schedule of Accounts Receivabale, Net (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified
Receivables [Abstract]
Accounts receivable, gross	$63,001	$64,620
Allowance for doubtful accounts	-58	-157	0	0
Accounts receivable, net	$62,943	$64,463

ACCOUNTS_RECEIVABLE_NET_Schedu1

ACCOUNTS RECEIVABLE, NET - Schedule of Allowance for Doubtful Accounts (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$157	$0	$0
Charges to expense	92	415	0
Write-offs	-191	-258	0
Balance at end of year	$58	$157	$0

INVENTORY_Details

INVENTORY - (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]
On-hand final assemblies and finished goods inventories	$19,285	$19,070
Deferred cost of goods sold	2,829	4,387
Gross inventory	22,114	23,457
Less current portion	-22,114	-21,793
Noncurrent portion (included in other assets)	$0	$1,664

PROPERTY_AND_EQUIPMENT_Schedul

PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$95,577	$107,634
Less accumulated depreciation and amortization	-77,732	-88,532
Property and equipment, net	17,845	19,102
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	2 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Property and equipment, gross	65,703	80,710
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Property and equipment, gross	17,342	15,410
Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	2 years
Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	612	855
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Property and equipment, gross	$11,920	$10,659
Leasehold Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	1 year
Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years

PROPERTY_AND_EQUIPMENT_Narrati

PROPERTY AND EQUIPMENT - Narrative (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Depreciation and amortization of property and equipment	$11,488	$12,329	$12,891

PROPERTY_AND_EQUIPMENT_Propert

PROPERTY AND EQUIPMENT - Property and Equipment Under Capital Leases (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Abstract]
Cost	$113	$326
Less accumulated depreciation	-71	-220
Property and equipment under capital leases, net	$42	$106

PROPERTY_AND_EQUIPMENT_Propert1

PROPERTY AND EQUIPMENT - Property and Equipment by Geographic Area (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property and equipment, net	$17,845	$19,102
United States [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	12,652	13,960
Asia/Pacific [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	3,574	4,665
Europe [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	765	453
Other [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	$854	$24

INTANGIBLE_ASSETS_AND_GOODWILL2

INTANGIBLE ASSETS AND GOODWILL - (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Aug. 24, 2012
Intangible Assets And Goodwill
Weighted average amortization period (years)	5 years 9 months 0 days	4 years 4 months 6 days
Cost	$34,049	$16,949
Accumulated amortization	11,455	6,858
Net carrying value	22,594	10,091
Amortization expense	4,597	4,546	2,773
Impairment of intangible assets	0	600	0
Estimated future amortization expense for intangible assets
2015	5,646
2016	5,290
2017	5,259
2018	2,953
2019	2,263
Thereafter	1,183
Total	22,594
Goodwill [Roll Forward]
Goodwill	42,369	35,485	35,485
Accumulated impairment losses	-3,106	-3,106	-3,106
Goodwill at the beginning of the period	32,379	32,379
Acquisition of NET	8,781	0
Goodwill, Written off Related to Sale of Business Unit	-1,897	0
Goodwill at the end of the period	39,263	32,379	32,379
Intellectual Property [Member]
Intangible Assets And Goodwill
Weighted average amortization period (years)	5 years	5 years
Cost	999	999
Accumulated amortization	999	999
Net carrying value	0	0
Amortization expense	0	200	400
Developed technology [Member]
Intangible Assets And Goodwill
Weighted average amortization period (years)	6 years 2 months 6 days	5 years 0 months 11 days
Cost	22,280	9,080
Accumulated amortization	5,193	2,729
Net carrying value	17,087	6,351
Amortization expense	2,464	1,999	730
Customer relationships [Member]
Intangible Assets And Goodwill
Weighted average amortization period (years)	5 years 6 months 27 days	5 years 3 months 18 days
Cost	10,040	6,140
Accumulated amortization	4,695	2,806
Net carrying value	5,345	3,334
Amortization expense	1,889	2,104	702
Order backlog [Member]
Intangible Assets And Goodwill
Amortization expense	0	0	860
Internal use software [Member]
Intangible Assets And Goodwill
Weighted average amortization period (years)	3 years	3 years
Cost	730	730
Accumulated amortization	568	324
Net carrying value	162	406
Amortization expense	244	243	81
NET [Member]
Goodwill [Roll Forward]
Goodwill at the beginning of the period				27,317
Goodwill at the end of the period				$27,317

ACCRUED_EXPENSES_Details

ACCRUED EXPENSES - (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]
Employee compensation and related costs	$20,042	$20,683
Other	12,107	13,343
Total	$32,149	$34,026

RESTRUCTURING_ACCRUAL_Details

RESTRUCTURING ACCRUAL - (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	facilities		facilities
RESTRUCTURING ACCRUAL
Number of locations	3		3
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	$4,345,000	$5,235,000
Restructuring	5,625,000	5,411,000	7,675,000
Cash payments		-6,301,000
Balance at the end of the period	5,334,000	4,345,000	5,235,000
Other Long Term Liabilities [Member]
RESTRUCTURING ACCRUAL
Accrued restructuring	1,900,000
Employee Severance and Facilities [Member]
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	4,345,000
Restructuring	5,435,000
Cash payments	-4,446,000
Balance at the end of the period	5,334,000
Employee severance [Member]
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	1,333,000	1,135,000
Restructuring	3,615,000	5,102,000	3,237,000
Cash payments	-3,266,000	-4,904,000
Balance at the end of the period	1,682,000	1,333,000	1,135,000
Facilities [Member]
Restructuring Reserve [Roll Forward]
Balance at the beginning of the period	3,012,000	4,100,000
Restructuring	1,820,000	309,000	4,133,000
Cash payments	-1,180,000	-1,397,000
Balance at the end of the period	3,652,000	3,012,000	4,100,000
Facilities [Member] | CALIFORNIA [Member]
Restructuring Reserve [Roll Forward]
Restructuring			4,000,000
Asset write-offs [Member]
Restructuring Reserve [Roll Forward]
Restructuring	190,000		305,000
PT [Member]
Restructuring Reserve [Roll Forward]
Restructuring	2,300,000
PT [Member] | Employee severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring	1,700,000
PT [Member] | Facilities [Member]
Restructuring Reserve [Roll Forward]
Restructuring	500,000
PT [Member] | Asset write-offs [Member]
Restructuring Reserve [Roll Forward]
Restructuring	$100,000

DEBT_Details

DEBT - (Details) (USD $)	12 Months Ended			1 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2007	Sep. 26, 2012	31-May-89	Jun. 27, 2014	Aug. 24, 2012	Aug. 27, 2012
DEBT
Payment of aggregate principal amount of debentures	$2,380,000	$0	$31,824,000
NET [Member]
DEBT
Cash consideration per share of the acquired entity (in dollars per share)								$1.35
2007 Notes [Member] | NET [Member]
DEBT
Interest rate	3.75%
Amount of debt issued				85,000,000
Amount of debt assumed and outstanding at the acquisition date								10,500,000
Percentage of principal amount at which notes may be required to be repurchased in event of fundamental change	100.00%
Repurchase of aggregate principal amounts									8,100,000
Aggregate principal amounts remaining outstanding	2,400,000
1989 Debentures [Member] | NET [Member]
DEBT
Interest rate	7.25%
Amount of debt issued						75,000,000
Amount of debt assumed and outstanding at the acquisition date								23,700,000
Percentage of principal amount at which notes may be required to be repurchased in event of fundamental change	100.00%
Payment of aggregate principal amount of debentures					23,700,000
Payment of accrued interest on debentures					600,000
Revolving Credit Facility [Member]
DEBT
Line of Credit Facility, Maximum Borrowing Capacity							40,000,000
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage							0.15%
Line of Credit Facility, Covenant, Minimum Cash and Cash Equivalent							$100,000,000
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member]
DEBT
Basis spread on variable rate	1.50%
Eurodollar [Member] | Revolving Credit Facility [Member]
DEBT
Interest rate							1.00%
Minimum [Member] | Federal Funds Rate [Member] | Revolving Credit Facility [Member]
DEBT
Basis spread on variable rate	0.50%
Maximum [Member] | Federal Funds Rate [Member] | Revolving Credit Facility [Member]
DEBT
Basis spread on variable rate	1.00%

LONGTERM_LIABILITIES_Schedule_

LONG-TERM LIABILITIES - Schedule of Long-Term Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Liabilities [Abstract]
Capital lease obligations	$70,000	$154,000
Deferred rent	3,160,000	3,057,000
Restructuring	5,334,000	4,345,000	5,235,000
Other	1,125,000	0
Long-term liabilities	9,689,000	7,556,000
Current portion	-4,443,000	-3,185,000
Other long-term liabilities	5,246,000	4,371,000
Current portion of accrued restructuring	$3,400,000	$2,500,000

COMMON_STOCK_REPURCHASES_AND_U1

COMMON STOCK REPURCHASES AND UNDERWRITTEN OFFERING (Details) (USD $)	0 Months Ended	12 Months Ended			0 Months Ended
	Mar. 20, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 29, 2013
Class of Stock [Line Items]
Repurchase and retirement of common stock		$18,000,000
Payments for repurchase of common stock	75,300,000	93,224,000	59,674,000	0
Shares repurchased and retired, shares		1,000,000	3,700,000
Remaining authorized purchase amount		22,800,000
Stock Issued During Period, Shares, New Issues	7,500,000
Over-allotment Option Period	30 days
Stock Issued During Period, Shares, New Issues, Over-Allotment Option	1,125,000
Stock Repurchased During Period, Shares	4,300,000
Stock Repurchased During Period, Price Per Share	$17.44
Transaction Fees	300,000
Common Stock [Member]
Class of Stock [Line Items]
Authorized amount					$100,000,000

STOCKBASED_COMPENSATION_PLANS_1

STOCK-BASED COMPENSATION PLANS - Reverse Stock Split (Details) (USD $)	0 Months Ended
	Jan. 30, 2015	Dec. 31, 2014	Dec. 01, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Common stock, shares authorized		120,000,000	600,000,000	120,000,000
Common stock, par value (in dollars per share)		$0.00		$0.00
Subsequent Event [Member]
Class of Stock [Line Items]
Stock split ratio	0.2

STOCKBASED_COMPENSATION_PLANS_2

STOCK-BASED COMPENSATION PLANS - 2007 Stock Incentive Plan (Details)	0 Months Ended
	Dec. 02, 2014	Dec. 01, 2014	Jun. 16, 2010	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)				5,586,190
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares outstanding				370,182	247,747
Amended 2007 plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized (in shares)	2,000,000		4,200,000
Maximum shares per employee	40,000	20,000
Conversion factor used to convert a number of shares available for grant into the entity's equity awards	1.57	1.5
Shares available for future issuance (in shares)				3,446,366
Options outstanding		810,064
Options and restricted stock outstanding		812,064
Return rate of shares	1.25
Amended 2007 plan [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares outstanding		2,000
Incentive Plan 2008 and 2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future issuance (in shares)		313,747

STOCKBASED_COMPENSATION_PLANS_3

STOCK-BASED COMPENSATION PLANS - 2008 and 2012 Stock Incentive Plans (Details) (USD $)	12 Months Ended			0 Months Ended	3 Months Ended	0 Months Ended	11 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 19, 2014	Sep. 26, 2014	Aug. 24, 2012	Nov. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business acquisition purchase consideration - assumed equity awards	$1,671	$0	$892
Fair value of the assumed awards attributable to future stock-based compensation expense	28,000
Weighted average period to record stock-based compensation expenses	3 years
2008 plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion factor used to convert a number of shares available for grant into the entity's equity awards	1.25
PT [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion factor used to convert a number of shares available for grant into the entity's equity awards					1.23
Acquisition consideration per share (in dollars per share)				$3.75
Assumption of equity awards in connection with acquisition of Network Technologies, Inc.				1,671
Fair value of the assumed awards attributable to future stock-based compensation expense				900
Weighted average period to record stock-based compensation expenses				1 year
NET [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Acquisition consideration per share (in dollars per share)						$1.35
Business acquisition purchase consideration - assumed equity awards						892
NET [Member] | 2008 plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business acquisition purchase consideration - assumed equity awards	900
Fair value of the assumed awards attributable to future stock-based compensation expense	$400
Weighted average period to record stock-based compensation expenses	8 months
NET [Member] | 2008 plan [Member] | Sonus Equity Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion factor used to convert a number of shares available for grant into the entity's equity awards							0.75
Acquisition consideration per share (in dollars per share)						$1.35
Number of consecutive trading days used to calculate conversion price of shares	10 days

STOCKBASED_COMPENSATION_PLANS_4

STOCK-BASED COMPENSATION PLANS - Executive and Board of Directors Equity Arrangements (Details) (USD $)

12 Months Ended

0 Months Ended

1 Months Ended

Dec. 31, 2014

Feb. 15, 2013

Feb. 15, 2014

Jun. 11, 2014

Aug. 15, 2013

Jul. 09, 2014

Jan. 22, 2014

Feb. 18, 2014

Mar. 29, 2013

Sep. 16, 2014

Sep. 15, 2014

Jan. 02, 2014

Aug. 10, 2012

executives

executives

executives

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Incremental stock-based compensation expense

$700,000

Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grant-date fair value (in dollars per share)

$17.03

Awards granted

553,609

February 15, 2013 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Executives

8

February 15, 2013 [Member] | Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Subscription rate as a percentage of bonus

100.00%

Award vesting percentage

50.00%

Board Member [Member] | Stock options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Exercisable period

3 years

Chief Executive Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Officers' Compensation

$600,000

$500,000

Chief Executive Officer [Member] | Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Maximum employee subscription rate

150.00%

Chief Executive Officer [Member] | August 10, 2012 [Member] | Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Maximum employee subscription rate

150.00%

Award vesting percentage

50.00%

50.00%

Executives [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Executives

21

Grant-date fair value (in dollars per share)

$19.25

Executives [Member] | February 18, 2014 [Member] | Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Executives

21

Subscription rate as a percentage of bonus

150.00%

Awards granted

0

Executives [Member] | Bonus 2014 - Entirely in shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Executives

17

Percent of shares awarded for bonus

100.00%

Subscription rate as a percentage of bonus

150.00%

Executives [Member] | Bonus 2014 - Half in shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Executives

4

Percent of shares awarded for bonus

50.00%

Percent of bonus awarded in cash

50.00%

Cash portion of bonus, percent of 2014 Bonus earned

50.00%

Subscription rate as a percentage of bonus

150.00%

STOCKBASED_COMPENSATION_PLANS_5

STOCK-BASED COMPENSATION PLANS - Other Dislocures (Details) (USD $)	12 Months Ended			0 Months Ended			37 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 09, 2014	Dec. 02, 2014	Dec. 01, 2014	Oct. 31, 2012
Weighted average exercise price
Granted (in dollars per share)	$17.97
Range of assumptions used in estimating fair value of options
Expected dividends	0.00%	0.00%	0.00%
Expected life			4 years 6 months
Cash received from the exercise of stock options (in dollars)	$10,117,000	$2,669,000	$254,000
Weighted average grant-date fair value
Total fair value of restricted stock awards, restricted stock units and performance-based stock awards on date vested	8,425,000	6,816,000	1,640,000
Stock-based compensation (in dollars)	23,914,000	17,873,000	9,003,000
Shares available for future issuance (in shares)	5,586,190
Minimum [Member]
Range of assumptions used in estimating fair value of options
Expected life	4 years 6 months
Maximum [Member]
Range of assumptions used in estimating fair value of options
Expected life	6 years
Product cost of revenue [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars)	337,000	181,000	162,000
Service cost of revenue [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars)	1,449,000	1,050,000	813,000
Research and development [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars)	5,759,000	3,616,000	2,297,000
Sales and marketing [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars)	5,437,000	4,780,000	2,006,000
General and administrative [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars)	10,932,000	8,246,000	3,725,000
Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Number of shares
Outstanding at the beginning of the period (in shares)	6,627,137
Granted (in shares)	2,331,174
PT outstanding options converted to Sonus options	256,548
Exercised (in shares)	-806,385
Forfeited (in shares)	-548,826
Expired (in shares)	-338,216
Outstanding at the end of the period (in shares)	7,521,432	6,627,137
Vested or expected to vest at the end of the period (in shares)	6,985,686
Exercisable at the end of the period (in shares)	3,651,057
Weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$16.11
PT outstanding options converted to Sonus options	$8.65
Exercised (in dollars per share)	$12.64
Forfeited (in dollars per share)	$14.66
Expired (in dollars per share)	$25.89
Outstanding at the end of the period (in dollars per share)	$16.47	$16.11
Vested or expected to vest at the end of the period (in dollars per share)	$16.47
Exercisable at the end of the period (in dollars per share)	$16.86
Weighted average remaining contractual life (in years)
Outstanding at the end of the period	6 years 10 months 29 days
Vested or expected to vest at the end of the period	6 years 9 months 8 days
Exercisable at the end of the period	5 years 1 month 22 days
Aggregate intrinsic value (in dollars)
Outstanding at the end of the period (in dollars)	31,319,000
Vested or expected to vest at the end of the period (in dollars)	29,528,000
Exercisable at the end of the period (in dollars)	16,809,000
Range of assumptions used in estimating fair value of options
Risk-free interest rates, minimum	1.53%	0.82%	0.67%
Risk-free interest rates, maximum	2.70%	1.71%	0.89%
Weighted average volatility	60.80%	63.20%	67.40%
Weighted average grant date fair value of stock options granted (in dollars per share)	$8.32	$7.71	$6.44
Total intrinsic values of stock options exercised (in dollars)	5,100,000	1,300,000	200,000
Cash received from the exercise of stock options (in dollars)	10,100,000	2,700,000	300,000
Restricted Stock [Member]
Change in unvested restricted stock awards
Unvested balance at the beginning of the period (in shares)	247,747
Granted (in shares)	553,609
Vested (in shares)	-428,674
Forfeited (in shares)	-2,500
Unvested balance at the end of the period (in shares)	370,182	247,747
Weighted average grant-date fair value
Unvested balance at the end of the period (in dollars per share)	$14.08
Granted (in dollars per share)	$17.03
Vested (in dollars per share)	$15.63
Forfeited (in dollars per share)	$7
Unvested balance at end of the period (in dollars per share)	$16.74	$14.08
Total fair value of restricted stock awards, restricted stock units and performance-based stock awards on date vested	$6,700,000	$2,400,000	$1,800,000
Performance share awards [Member]
Change in unvested restricted stock awards
Unvested balance at the beginning of the period (in shares)	211,906
Granted (in shares)	0
Vested (in shares)	-136,526
Forfeited (in shares)	-41,145
Unvested balance at the end of the period (in shares)	34,235
Weighted average grant-date fair value
Unvested balance at the end of the period (in dollars per share)	$12.98
Granted (in dollars per share)	$0
Vested (in dollars per share)	$12.63
Forfeited (in dollars per share)	$13.60
Unvested balance at end of the period (in dollars per share)	$13.60
Executives [Member]
Weighted average grant-date fair value
Granted (in dollars per share)				$19.25
Amended 2007 plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	10 years
Number of shares
Outstanding at the beginning of the period (in shares)					810,064	810,064
Weighted average grant-date fair value
Maximum shares per employee					40,000	20,000
Shares available for future issuance (in shares)	3,446,366
Amended 2007 plan [Member] | Restricted Stock [Member]
Change in unvested restricted stock awards
Unvested balance at the beginning of the period (in shares)						2,000
Unvested balance at the end of the period (in shares)						2,000
2008 plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	7 years
2012 plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	5 years
ESPP [Member]
Weighted average grant-date fair value
Percentage of purchase price	85.00%
Maximum shares per employee	500
Number of shares authorized	5,000,000
Shares available for future issuance (in shares)	2,139,824
Annual Vesting Period [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	25.00%
Annual Vesting Period [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage							25.00%
Monthly Vesting Period [Member] | Stock options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	75.00%
Semi Annual Vesting Period [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage							75.00%

EMPLOYEE_DEFINED_CONTRIBUTION_1

EMPLOYEE DEFINED CONTRIBUTION PLAN - (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Percentage of matching contribution			50.00%
Maximum amount of company match			$3,500
401(k) expense	$0	$0	$1,700,000

INCOME_TAXES_Schedule_of_Incom

INCOME TAXES - Schedule of Income (Loss) Before Taxes (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loss before income taxes:
United States	($16,582)	($21,076)	($49,337)
Foreign	1,941	409	1,609
Loss before income taxes	($14,641)	($20,667)	($47,728)

INCOME_TAXES_Schedule_of_Incom1

INCOME TAXES - Schedule of Income Tax Expense (Benefit) (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current:
Federal	$23	$14	$14
State	150	150	105
Foreign	926	1,696	1,465
Total current	1,099	1,860	1,584
Deferred:
Federal	-3,885	-1,911	-12,441
State	-1,656	-103	-1,680
Foreign	414	-1,081	607
Change in valuation allowance	6,242	2,687	14,371
Total deferred	1,115	-408	857
Total	$2,214	$1,452	$2,441

INCOME_TAXES_Schedule_of_Effec

INCOME TAXES - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
U.S Statutory income tax rate	-35.00%	-35.00%	-35.00%
State income taxes, net of federal benefit	-4.90%	0.40%	-3.60%
Foreign income taxes	5.10%	1.30%	3.20%
Capital loss expiration	0.00%	24.00%	0.00%
Foreign dividends	11.50%	1.80%	2.10%
Stock-based compensation	12.00%	7.60%	3.40%
Tax credits	-14.60%	-6.10%	-0.70%
Deferred cost of goods sold elimination	0.00%	0.00%	-1.20%
Valuation allowance	29.80%	9.90%	35.50%
Goodwill amortization	4.80%	3.30%	0.50%
Meals and entertainment	2.50%	1.30%	0.70%
Tax gain on acquired assets	4.20%	0.00%	0.00%
Other, net	-0.30%	-1.50%	0.20%
Effective income tax rate	15.10%	7.00%	5.10%

INCOME_TAXES_Summary_of_Deferr

INCOME TAXES - Summary of Deferred Tax Assets and Liabilities (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:
Net operating loss carryforwards	$74,717	$64,811
Research and development tax credits	24,978	21,401
Other tax credits	91	160
Intangible assets	4,808	2,530
Deferred revenue	1,911	4,143
Accrued expenses	10,619	10,519
Inventory	5,713	6,498
Stock-based compensation	12,913	9,263
Other temporary differences	3,924	3,642
Deferred tax assets, gross	139,674	122,967
Valuation allowance	-137,640	-119,616
Total deferred tax assets	2,034	3,351
Liabilities:
Purchased intangible assets	-1,623	-922
Unrealized gain on available-for-sale securities	0	-574
Total deferred tax liabilities	-1,623	-1,496
Total net deferred tax assets	411	1,855
Deferred income taxes - current assets	991	656
Deferred income taxes - noncurrent assets	1,043	0
Deferred income taxes - noncurrent liabilities	($1,623)	$1,199

INCOME_TAXES_Operating_Loss_Na

INCOME TAXES - Operating Loss Narrative (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, except Per Share data, unless otherwise specified
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$215
Portion of operating loss carryforwards for stock option deductions	138
Operating carryforward not recognized	22.4
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	109
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	0.1
Foreign Tax Authority [Member] | Japan [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$0.90
Stock options [Member]
Operating Loss Carryforwards [Line Items]
Weighted average exercise price (in usd per share)	$16.47	$16.11

INCOME_TAXES_Tax_Carryforward_

INCOME TAXES - Tax Carryforward Narrative (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 26, 2008
Tax Carryforward [Line Items]
Deferred tax assets, stock-based compensation	$12,913,000	$9,263,000
Tax credit carryforward	25,000,000
Deferred tax assets, valuation allowance	137,640,000	119,616,000
Unrecognized tax penalties and interest	14,000	14,000	14,000
Zynetix [Member] | Capital Loss Carryforward [Member]
Tax Carryforward [Line Items]
Tax credit carryforward				14,100,000
Deferred tax asset, capital loss carryforwards	$5,500,000

INCOME_TAXES_Schedule_of_Unrec

INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at the beginning of the period	$8,861	$8,847	$10,004
Increases related to current year tax positions	14	14	14
Decreases related to prior period tax positions	0	0	-1,171
Unrecognized tax benefits at the end of the period	$8,875	$8,861	$8,847

MAJOR_CUSTOMERS_Details

MAJOR CUSTOMERS - (Details) (Customer [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue [Member] | AT&T [Member]
MAJOR CUSTOMERS
Concentration risk, percentage	19.00%	15.00%	20.00%
Accounts receivable balance [Member]
MAJOR CUSTOMERS
Concentration risk, percentage		13.00%
Number of major customers	0	1

GEOGRAPHIC_AND_OPERATING_SEGME2

GEOGRAPHIC AND OPERATING SEGMENT INFORMATION - Summary of Revenue by Geographic Area as a Percentage of Total Revenue (Details) (Revenue [Member], Geographical area [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue by geographic area and by customer
Percentage of total revenue	100.00%	100.00%	100.00%
United States [Member]
Revenue by geographic area and by customer
Percentage of total revenue	71.00%	69.00%	68.00%
Europe, Middle East and Africa [Member]
Revenue by geographic area and by customer
Percentage of total revenue	13.00%	12.00%	13.00%
Japan [Member]
Revenue by geographic area and by customer
Percentage of total revenue	9.00%	12.00%	14.00%
Other Asia Pacific [Member]
Revenue by geographic area and by customer
Percentage of total revenue	5.00%	5.00%	4.00%
Other [Member]
Revenue by geographic area and by customer
Percentage of total revenue	2.00%	2.00%	1.00%

GEOGRAPHIC_AND_OPERATING_SEGME3

GEOGRAPHIC AND OPERATING SEGMENT INFORMATION - Summary by Product and Type of Service (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Service	$113,871	$109,461	$100,808
Services, Maintenance [Member]
Revenue from External Customer [Line Items]
Service	90,003	84,698	76,423
Services, Professional services [Member]
Revenue from External Customer [Line Items]
Service	$23,868	$24,763	$24,385

COMMITMENTS_AND_CONTINGENCIES_1

COMMITMENTS AND CONTINGENCIES - Leases Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	sqft
Commitments and Contingencies Disclosure [Abstract]
Area of leased facility (in sqft)	97,500
Rent expense	$6,100,000	$5,500,000	$5,000,000
Years ending December 31,
2015	6,330,000
2016	5,506,000
2017	3,855,000
2018	2,929,000
2019	1,351,000
Thereafter	38,000
Operating lease, future minimum payments	$20,009,000

SUBSEQUENT_EVENT_Details

SUBSEQUENT EVENT - (Details) (Subsequent Event [Member], SDN Business [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Jan. 02, 2015
Subsequent Event [Line Items]
Cash consideration	$10.10
Period shares are issuable	3 years
Number of shares issuable	3.5
Common stock issued if revenue threshold of $60 million is met [Member]
Subsequent Event [Line Items]
Revenue threshold	60
Number of shares issuable	1.3
Common stock issued if revenue threshold of $150 million is met [Member]
Subsequent Event [Line Items]
Revenue threshold	$150
Number of shares issuable	2.2

QUARTERLY_RESULTS_UNAUDITED_De

QUARTERLY RESULTS (UNAUDITED) - (Details) (USD $)	3 Months Ended																12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014		Sep. 26, 2014		Jun. 27, 2014		Mar. 28, 2014		Dec. 31, 2013		Sep. 27, 2013		Jun. 28, 2013		Mar. 29, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenue	$76,798		$73,216		$75,570		$70,742	[1]	$76,153		$68,099		$69,193		$63,288		$296,326	$276,733	$254,134
Cost of revenue	25,006		25,314		28,282		24,319	[1]	27,767		25,835		25,185		25,486		102,921	104,273	111,540
Gross profit	51,792		47,902		47,288		46,423	[1]	48,386		42,264		44,008		37,802		193,405	172,460	142,594
Income (loss) from operations	-1,945		-4,715		-4,801		-5,791	[1]	-59		-2,911		-4,633		-13,472		-17,252	-21,075	-48,542
Net loss	($2,192)		($5,213)		($5,497)		($3,953)	[1]	$272		($3,773)		($4,870)		($13,748)		($16,855)	($22,119)	($50,169)
Loss per share:
Basic (in dollars per share)	($0.04)	[2]	($0.11)	[2]	($0.11)	[2]	($0.07)	[1],[2]	$0.01	[2]	($0.07)	[2]	($0.09)	[2]	($0.24)	[2]	($0.34)	($0.40)	($0.90)
Diluted (in dollars per share)	($0.04)	[2]	($0.11)	[2]	($0.11)	[2]	($0.07)	[1],[2]	$0	[2]	($0.07)	[2]	($0.09)	[2]	($0.24)	[2]	($0.34)	($0.40)	($0.90)
Shares used in computing loss per share:
Basic (in shares)	49,361		49,291		49,424		53,080	[1]	54,188		55,855		56,478		56,308		50,245	55,686	56,018
Diluted (in shares)	49,361		49,291		49,424		53,080	[1]	54,699		55,855		56,478		56,308		50,245	55,686	56,018
[1]	(1)Includes the results of PT for the period subsequent to February 19, 2014.
[2]	Earnings (loss) per share is calculated independently for each of the quarters presented; accordingly, the sum of the quarterly earnings (loss) per share amounts may not equal the total calculated for the year.