Ribbon Communications Inc - Ordinary Shares 10-Q 29 Apr 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 28, 2014	Apr. 23, 2014
Document And Entity Information	'	'
Entity Registrant Name	'SONUS NETWORKS INC	'
Entity Central Index Key	'0001105472	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	28-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	247,783,540
Entity Well-known Seasoned Issuer	'No	'
Entity Voluntary Filers	'No	'
Entity Current Reporting Status	'Yes	'

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$71,771	$72,423
Marketable securities	87,446	138,882
Accounts receivable, net of allowance for doubtful accounts of $157 at March 28, 2014 and December 31, 2013	45,677	64,463
Inventory	24,178	21,793
Deferred income taxes	693	656
Other current assets	16,741	15,073
Total current assets	246,506	313,290
Property and equipment, net	20,968	19,102
Intangible assets, net	26,162	10,091
Goodwill	40,572	32,379
Investments	0	34,364
Deferred income taxes	2,133	2,121
Other assets	6,010	6,137
Total assets	342,351	417,484
Current liabilities:	'	'
Accounts payable	9,741	11,164
Accrued expenses	25,689	34,026
Current portion of deferred revenue	42,179	41,169
Convertible subordinated note	2,380	2,380
Current portion of long-term liabilities	701	672
Total current liabilities	80,690	89,411
Deferred revenue	10,081	10,528
Deferred income taxes	1,199	922
Other long-term liabilities	4,193	4,371
Total liabilities	96,163	105,232
Commitments and contingencies (Note 16)	'	'
Stockholders' equity:	'	'
Preferred stock, $0.01 par value per share; 5,000,000 shares authorized, none issued and outstanding	0	0
Common stock, $0.001 par value per share; 600,000,000 shares authorized; 247,707,063 shares issued and outstanding at March 28, 2014; 266,226,845 shares issued and outstanding at December 31, 2013	248	266
Additional paid-in capital	1,218,311	1,280,442
Accumulated deficit	-978,445	-974,492
Accumulated other comprehensive income	6,074	6,036
Total stockholders' equity	246,188	312,252
Total liabilities and stockholders' equity	$342,351	$417,484

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Allowance for doubtful accounts	$157	$157
Preferred stock, par value (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	5,000,000	5,000,000
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	600,000,000	600,000,000
Common stock, shares issued	247,707,063	266,226,845
Common stock, shares outstanding	247,707,063	266,226,845

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Revenue:	'	'
Product	$45,140	$37,796
Service	25,602	25,492
Total revenue	70,742	63,288
Cost of revenue:	'	'
Product	13,663	13,895
Service	10,656	11,591
Total cost of revenue	24,319	25,486
Gross profit	46,423	37,802
Operating expenses:	'	'
Research and development	18,972	17,501
Sales and marketing	19,581	21,114
General and administrative	11,186	10,710
Acquisition-related	1,306	0
Restructuring	1,169	1,949
Total operating expenses	52,214	51,274
Loss from operations	-5,791	-13,472
Interest income, net	35	138
Other income, net	2,335	0
Loss before income taxes	-3,421	-13,334
Income tax provision	-532	-414
Net loss	($3,953)	($13,748)
Loss per share	'	'
Basic (in dollars per share)	($0.01)	($0.05)
Diluted (in dollars per share)	($0.01)	($0.05)
Shares used to compute loss per share:	'	'
Basic (in shares)	265,400	281,542
Diluted (in shares)	265,400	281,542

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net loss	($3,953)	($13,748)
Other comprehensive income (loss), net of tax:	'	'
Foreign currency translation adjustments	94	-326
Unrealized loss on available-for sale marketable securities, net of tax	-10	-83
Other comprehensive income (loss), net of tax	84	-409
Comprehensive loss, net of tax	($3,869)	($14,157)

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013
Cash flows from operating activities:	'	'
Net loss	($3,953)	($13,748)
Adjustments to reconcile net loss to cash flows provided by (used in) operating activities:	'	'
Depreciation and amortization of property and equipment	2,917	3,522
Amortization of intangible assets	1,029	1,187
Stock-based compensation	5,774	4,224
Loss on disposal of property and equipment	55	17
Deferred income taxes	176	183
Changes in operating assets and liabilities:	'	'
Accounts receivable	22,973	17,472
Inventory	2,337	-837
Other operating assets	-259	1,515
Accounts payable	-1,551	-4,637
Accrued expenses and other long-term liabilities	-7,754	-4,329
Deferred revenue	-538	1,739
Net cash provided by operating activities	21,206	6,308
Cash flows from investing activities:	'	'
Purchases of property and equipment	-3,287	-1,005
Business acquisition, net of cash acquired	-34,010	0
Purchases of marketable securities	0	-76,526
Maturities/sales of marketable securities	87,646	57,110
Net cash provided by (used in) investing activities	50,349	-20,421
Cash flows from financing activities:	'	'
Proceeds from sale of common stock in connection with employee stock purchase plan	1,197	865
Proceeds from exercise of stock options	3,444	578
Payment of tax withholding obligations related to net share settlements of restricted stock awards	-1,530	-346
Repurchase of common stock	-75,385	0
Principal payments of capital lease obligations	-24	-31
Net cash (used in) provided by financing activities	-72,298	1,066
Effect of exchange rate changes on cash and cash equivalents	91	-329
Net decrease in cash and cash equivalents	-652	-13,376
Cash and cash equivalents, beginning of year	72,423	88,004
Cash and cash equivalents, end of period	71,771	74,628
Supplemental disclosure of cash flow information:	'	'
Interest paid	2	2
Income taxes paid	751	555
Income tax refunds received	0	3
Supplemental disclosure of non-cash investing activities:	'	'
Capital expenditures incurred, but not yet paid	384	186
Business acquisition purchase consideration - assumed equity awards	$1,671	$0

BASIS_OF_PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 28, 2014
Accounting Policies [Abstract]	'
BASIS OF PRESENTATION	'
	BASIS OF PRESENTATION
	Business
	Sonus Networks, Inc. (“Sonus” or the “Company”) was incorporated in 1997 and 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 voice and data communication networks, reduce expenses and position themselves to provide new services to their customers. Sonus helps many of the world's leading communications service providers and enterprises implement the next generation of Session Initiation Protocol ("SIP")-based solutions, including Voice over IP ("VoIP") 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 solutions address the need for communications service providers and enterprises to seamlessly link and leverage multivendor, multiprotocol communications systems and applications across a single network infrastructure. Previously, companies were required to implement separate networks for their voice and data applications. In a rapidly changing ecosystem of IP-enabled devices such as smartphones and tablets, companies want an infrastructure that enables the integration of voice and data capability into a single application on one integrated network. Sonus solutions help the Company's customers realize the intended value and benefits of UC platforms by enabling disparate vendor communications environments, commonplace in most enterprises today, to work seamlessly together. Likewise, Sonus solutions facilitate the deployment and adoption of cloud-based communications.
	The Company 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 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. The Company collaborates with its customers to identify and develop new, advanced services and applications that can help to reduce costs, improve productivity and generate new revenue.
	Basis of Presentation
	In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting only of normal recurring items, necessary for their fair presentation with accounting principles generally accepted in the United States of America ("GAAP") and with the rules and regulations of the U.S. Securities and Exchange Commission ("SEC").
	Interim results are not necessarily indicative of results for a full year or any future interim period. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2013 ("Annual Report") filed with the SEC effective February 28, 2014.
	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 condensed consolidated financial statements for the three months ended March 28, 2014 for the period subsequent to the PT Acquisition Date.
	Significant Accounting Policies
	The Company's significant accounting policies are disclosed in Note 2 to the Consolidated Financial Statements included in the Annual Report. There were no material changes to the significant accounting policies during the three months ended March 28, 2014.
	Principles of Consolidation
	The condensed consolidated financial statements include the accounts of Sonus and its wholly-owned subsidiaries. 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, including impairments, 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.
	Fair Value of Financial Instruments
	The carrying amounts of the Company's financial instruments, which include cash equivalents, marketable securities, investments, accounts receivable, accounts payable, convertible subordinated debt and other long-term liabilities, approximate their fair values.
	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.
	Recent Accounting Pronouncements
	On July 18, 2013, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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 condensed consolidated financial statements, as the Company already applied the methodology prescribed by ASU 2013-11.
	On March 4, 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 condensed consolidated financial statements.

ACQUISITION_OF_PT

ACQUISITION OF PT	3 Months Ended
	Mar. 28, 2014
Business Combinations [Abstract]	'
ACQUISITION OF PT	'
	ACQUISITION OF PT
	On February 19, 2014, the Company acquired all of the outstanding common stock of PT for cash consideration of $34.0 million, or $3.75 per share of PT common stock. The Company believes that this acquisition will enable 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 Company believes that the acquisition of PT will allow Sonus to diversify its 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 condensed consolidated financial statements for the period subsequent to its acquisition.
	As of March 28, 2014, the valuation of acquired assets, identifiable intangible assets, uncertain tax liabilities and certain accrued liabilities is preliminary. The Company is in the process of investigating the facts and circumstances existing as of the PT Acquisition Date in order to finalize its valuation of the assets acquired and liabilities assumed. Based on the preliminary purchase price allocation, the Company recorded $8.2 million of goodwill, primarily due to expected synergies between the combined companies and expanded market opportunities.
	The Company is determining whether it will make an election under Section 338(g) of the Internal Revenue Code to have the acquisition of PT 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 PT is as follows (in thousands):
	Fair value of consideration transferred:
	Cash, net of cash acquired	$	34,010
	Unpaid purchase consideration	1,012
	Fair value of equity awards assumed	1,671
	Fair value of total consideration	$	36,693
	Fair value of assets acquired and liabilities assumed:
	Marketable securities	$	2,315
	Other current assets	9,696
	Property and equipment	2,251
	Intangible assets	17,100
	Goodwill	8,193
	Current liabilities	(2,762		)
	Other long-term liabilities	(100		)
		$	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 preliminarily 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 6).
	The Company has not provided pro forma information as the results of PT are not material to the Company's financial results.
	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 PT executives under their respective PT change of control agreements.
	The components of acquisition-related costs included in the Company's results of operations for the three months ended March 28, 2014 are as follows (in thousands):
	Professional and services fees	$	1,057
	Change of control agreements	249
		$	1,306
	The Company did not record any acquisition-related expenses in the three months ended March 29, 2013.

EARNINGS_LOSS_PER_SHARE

EARNINGS (LOSS) PER SHARE	3 Months Ended
	Mar. 28, 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):
		Three months ended
		March 28,	March 29,
		2014	2013
	Weighted average shares outstanding—basic	265,400	281,542
	Potential dilutive common shares	—	—
	Weighted average shares outstanding—diluted	265,400	281,542
	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 Employee Stock Purchase Plan, as amended (the "ESPP") aggregating 45.3 million shares for the three months ended March 28, 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 and unvested shares of restricted stock aggregating 31.5 million shares for the three months ended March 29, 2013 have not been included in the computation of diluted loss per share because their effect would have been antidilutive.

CASH_EQUIVALENTS_MARKETABLE_SE

CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS	3 Months Ended
	Mar. 28, 2014
Investments, All Other Investments [Abstract]	'
CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS	'
	CASH EQUIVALENTS, MARKETABLE SECURITIES 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 three months ended March 28, 2014, the Company sold $45.9 million of its available-for-sale securities and realized gross gains aggregating $46,000. The Company did not realize any gross losses on these sales. In addition, $41.7 million of the Company's available-for-sale securities matured during the three months ended March 28, 2014 and were redeemed upon maturity. The Company did not sell any of its available-for-sale securities during the three months ended March 29, 2013, and accordingly, no such gains or losses were realized during such period.
	Marketable securities and investments with continuous unrealized losses for one year or greater at March 28, 2014 were nominal. Since the Company currently 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 marketable securities and investments to determine if there have been any events that could create a credit impairment. The increase in unrealized losses in the current year period primarily relates to the recent increase in interest rates. However, since the Company's entire investment portfolio has investment grade ratings with no indication of credit loss, the Company believes it will recover the entire amortized cost basis of these securities and does not believe these unrealized losses are other-than-temporary. Accordingly, the Company does not believe that any impairment existed with its current holdings at March 28, 2014.
	The amortized cost, gross unrealized gains and losses and fair value of the Company's marketable debt and equity securities and investments at March 28, 2014 and December 31, 2013 were comprised of the following (in thousands):
		28-Mar-14
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	10,363	$	—	$	—		$	10,363
	Marketable securities
	U.S. government agency notes	$	20,796	$	4	$	(1	)	$	20,799
	Corporate debt securities	63,597		11		(11		)	63,597
	Commercial paper	1,250		—		—			1,250
	Certificates of deposit	1,800		—		—			1,800
		$	87,443	$	15	$	(12	)	$	87,446
		31-Dec-13
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	50,404	$	—	$	—		$	50,404
	Marketable securities
	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 classified as Investments in the condensed consolidated balance sheet at December 31, 2013 had maturity dates after one year but within two years or less from the balance sheet date. The Company had no Investments recorded at March 28, 2014.
	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 March 28, 2014 and December 31, 2013. These financial assets are comprised of the Company's available-for-sale debt and equity securities and reported under the captions Cash and cash equivalents, Marketable securities and Investments in the consolidated balance sheets (in thousands):
				Fair value measurements at
				March 28, 2014 using:
		Total carrying		Quoted prices		Significant other			Significant
		value at		in active		observable			unobservable
		March 28,		markets		inputs			inputs
		2014		(Level 1)		(Level 2)			(Level 3)
	Cash equivalents	$	10,363	$	10,363	$	—		$	—
	Marketable securities
	U.S. government agency notes	$	20,799	$	—	$	20,799		$	—
	Corporate debt securities	63,597		—		63,597			—
	Commercial paper	1,250		—		1,250			—
	Certificates of deposit	1,800		—		1,800			—
		$	87,446	$	—	$	87,446		$	—
				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	$	—		$	—
	Marketable securities
	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 on the basis 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 condensed 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.

INVENTORY

INVENTORY	3 Months Ended
	Mar. 28, 2014
Inventory Disclosure [Abstract]	'
INVENTORY	'
	INVENTORY
	Inventory consists of the following (in thousands):
		March 28,			December 31,
		2014			2013
	Raw materials	$	968		$	—
	On-hand final assemblies and finished goods inventories	19,737			19,070
	Deferred cost of goods sold	4,056			4,387
		24,761			23,457
	Less current portion	(24,178		)	(21,793		)
	Noncurrent portion (included in Other assets)	$	583		$	1,664

INTANGIBLE_ASSETS_AND_GOODWILL

INTANGIBLE ASSETS AND GOODWILL	3 Months Ended
	Mar. 28, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
INTANGIBLE ASSETS AND GOODWILL	'
	INTANGIBLE ASSETS AND GOODWILL
	The Company's intangible assets at March 28, 2014 and December 31, 2013 consist of the following (dollars in thousands):
	March 28, 2014	Weighted average amortization period		Cost				Accumulated			Net
		(years)						amortization			carrying value
	Intellectual property	5		$	999			$	999		$	—
	Developed technology	6.18		22,280				3,299			18,981
	Customer relationships	5.57		10,040				3,204			6,836
	Internal use software	3		730				385			345
		5.75		$	34,049			$	7,887		$	26,162
	December 31, 2013	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 three months ended March 28, 2014 and March 29, 2013 was as follows (in thousands):
		Three months ended								Statement of operations classification
		March 28,				March 29,
		2014				2013
	Intellectual property	$	—			$	100			Research and development
	Developed technology	570				500				Cost of revenue - product
	Customer relationships	398				526				Sales and marketing
	Internal use software	61				61				Cost of revenue - product
		$	1,029			$	1,187
	Estimated future amortization expense for the Company's intangible assets at March 28, 2014 is as follows (in thousands):
	Years ending December 31,
	Remainder of 2014	$	3,568
	2015	5,647
	2016	5,290
	2017	5,259
	2018	2,953
	Thereafter	3,445
		$	26,162
	The changes in the carrying value of the Company's goodwill in the three months ended March 28, 2014 were as follows (in thousands):
	Balance at January 1, 2014:
	Goodwill	$	35,485
	Accumulated impairment losses	(3,106		)
		32,379
	Acquisition of PT	8,193
	Balance at March 28, 2014	$	40,572
	There were no changes to the carrying value of the Company's goodwill in the three months ended March 29, 2013.

ACCRUED_EXPENSES

ACCRUED EXPENSES	3 Months Ended
	Mar. 28, 2014
Payables and Accruals [Abstract]	'
ACCRUED EXPENSES	'
	ACCRUED EXPENSES
	Accrued expenses consist of the following (in thousands):
		March 28,		December 31,
		2014		2013
	Employee compensation and related costs	$	11,692	$	20,683
	Other	13,997		13,343
		$	25,689	$	34,026

RESTRUCTURING_ACCRUAL

RESTRUCTURING ACCRUAL	3 Months Ended
	Mar. 28, 2014
Restructuring and Related Activities [Abstract]	'
RESTRUCTURING ACCRUAL	'
	RESTRUCTURING ACCRUAL
	The Company recorded $1.2 million of restructuring expense in the three months ended March 28, 2014 for severance and related costs in connection with reducing its workforce and $1.9 million of restructuring expense in the three months ended March 29, 2013, primarily for severance and related costs in connection with reductions to the Company's workforce.
	The table below summarizes the restructuring accrual activity for the three months ended March 28, 2014 (in thousands):
		Balance at		Initiatives		Cash			Balance at
		January 1,		charged to		payments			March 28,
		2014		expense					2014
	Severance	$	1,333	$	1,169	$	(1,394	)	$	1,108
	Facilities	3,012		—		(295		)	2,717
		$	4,345	$	1,169	$	(1,689	)	$	3,825
	The Company expects to complete the restructuring payments related to severance in the fourth quarter of fiscal 2014 and the payments related to facilities in fiscal 2016. 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 condensed consolidated balance sheets. The long-term portions of accrued restructuring were $1.8 million at March 28, 2014 and $1.8 million at December 31, 2013.

DEBT

DEBT	3 Months Ended
	Mar. 28, 2014
Debt Disclosure [Abstract]	'
DEBT	'
	DEBT
	The Company has determined that the estimated fair value of its $2.4 million of aggregate principal amount of outstanding debt due in December 2014 equaled its carrying value at both March 28, 2014 and December 31, 2013. Although the debt can be publicly traded, there have been no trading transactions since 2010 and accordingly, the Company has categorized it in Level 2 within the fair value hierarchy.

STOCKHOLDER_RIGHTS_PLAN

STOCKHOLDER RIGHTS PLAN	3 Months Ended
	Mar. 28, 2014
Equity [Abstract]	'
STOCKHOLDER RIGHTS PLAN	'
	STOCKHOLDER RIGHTS PLAN
	On June 21, 2013, the Company entered into an amendment to its stockholder rights agreement, as amended (the "Rights Plan"), to extend the expiration date of the rights in such Rights Plan from June 26, 2013 to June 26, 2015. The amendment was not in response to any acquisition proposal and no other amendments were made to the Rights Plan. The Rights Plan was originally adopted on June 26, 2008 and subsequently extended to June 26, 2013 on June 10, 2011.
	Under the Rights Plan, preferred stock purchase rights (the "Rights") were distributed as a dividend at the rate of one Right per share of common stock held by stockholders of record as of the close of business on July 7, 2008. Each Right entitles the stockholder to purchase from the Company a unit consisting of one one-thousandth of a share (a "Unit") of preferred stock at a purchase price of $25.00, subject to adjustment.
	The Rights generally will be exercisable only if a person or group acquires beneficial ownership of 15% or more of the Company's common stock (which includes for this purpose shares of common stock referenced in derivative transactions or securities), or commences or publicly announces a tender or exchange offer upon consummation of which they would beneficially own 15% or more of the Company's common stock. Subject to certain conditions, a person or group who beneficially owned 15% or more of the outstanding shares of the Company's common stock prior to the adoption of the Rights Plan did not cause the Rights to become exercisable upon adoption of the Rights Plan. Should the Rights become exercisable, the effect would be to dilute the ownership of the beneficial owner(s) who triggered the Rights, as that beneficial owner or group of owners would not receive the Units.

COMMON_STOCK_REPURCHASES_AND_U

COMMON STOCK REPURCHASES AND UNDERWRITTEN OFFERING (Notes)	3 Months Ended
	Mar. 28, 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 Company has not implemented such a 10b5-1 repurchase program to date. The stock buyback program may be suspended or discontinued at any time. The buyback program is being funded using the Company's working capital. During the three months ended March 28, 2014, the Company spent approximately $144,000, including transaction fees, to repurchase and retire 38,500 shares of its common stock under the buyback program. At March 28, 2014, the Company had $40.6 million remaining under the stock buyback program for future repurchases.
	Underwritten Offering
	On March 20, 2014, the Company announced the commencement of an underwritten public offering of 37.5 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 5.625 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 21.5 million shares of its common stock from the underwriter for $3.4882 per share, the price equal to the price paid by the underwriter to the Legatum Group in the underwritten offering, for a total of $75.4 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	3 Months Ended
	Mar. 28, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
STOCK-BASED COMPENSATION PLANS	'
	STOCK-BASED COMPENSATION PLANS
	Stock Incentive Plans
	The Company's 2007 Stock Incentive Plan, as amended, (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.
	The Company's 2008 Stock Incentive Plan provides for the award of stock options, SARs, restricted stock, performance-based awards and RSUs to former employees of Network Equipment Technologies, Inc. ("NET") who subsequently became employees of Sonus and Sonus employees hired subsequent to the August 24, 2012, the date the Company acquired NET.
	In connection with the acquisition of PT, the Company assumed PT's 2012 Amended Performance Technologies, Incorporated Omnibus Incentive Plan (the "PT 2012 Plan"), which provides for the award of stock options, SARs, restricted stock, performance-based awards and restricted stock units. The Company also assumed all of the outstanding options to purchase common stock under the Performance Technologies, Incorporated 2003 Omnibus Incentive Plan (the "PT 2003 Plan") and the Performance Technologies, Incorporated 2001 Stock Option Plan (the "PT 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 PT 2012 Plan, the PT 2003 Plan and the PT 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 PT 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.
	Executive and Board of Directors Equity Arrangements
	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 243,507 shares of restricted stock (the "2014 Dolan Salary Shares") on January 2, 2014. The number of shares granted was 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 $3.08, the closing price of the Company's common stock on the date of grant. The 2014 Dolan Salary Shares will vest on December 31, 2014. If Mr. Dolan's employment is terminated by Mr. Dolan with Good Reason (as defined in his employment agreement, as amended) or his employment is terminated by the Company without Cause (as defined in his employment agreement, as amended) before December 31, 2014, a pro rata portion of the 2014 Dolan Salary Shares will vest on the date of such termination. If Mr. Dolan terminates his employment without Good Reason or his employment is terminated by the Company for Cause before December 31, 2014, he will forfeit the 2014 Dolan Salary Shares. The Company is recording stock-based compensation expense related to the 2014 Dolan Salary Shares ratably for the period of January 1, 2014 through December 31, 2014. The 2014 Dolan Salary Shares are included in the amount reported as "Granted" in the restricted stock grant table below.
	On January 22, 2014, 21 executives of the Company, including Mr. Dolan, were given the choice to receive all or half of their fiscal year 2014 bonuses (the "2014 Bonus"), if any are 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, if any, in the form of cash. The amount of the 2014 Bonus, if any, for each executive shall be determined by the Compensation Committee of the Board of Directors of the Company (the "Compensation Committee"). The number of shares of the Company's common stock that will be granted to those executives who elected to receive their 2014 Bonus entirely in the form of shares of common stock will be calculated by dividing an amount equal to 1.5 times each executive's 2014 Bonus earned by $3.08, the closing price of the Company's common stock on January 2, 2014. The number of shares of the Company's common stock that will be granted to those executives who elected to receive one-half of their 2014 Bonus in the form of shares of common stock will be calculated by dividing an amount equal to 1.5 times one-half of each executive's 2014 Bonus earned by $3.08, with the cash portion equal 50% of their respective 2014 Bonus earned. The 2014 Bonus, if any, will be granted and/or paid on a date concurrent with the timing of the payout of bonuses under the Company-wide cash bonus program. The 2014 Bonus Shares, if any are granted, will be fully vested on the date of grant. 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. As of March 28, 2014, the Company determined that the grant date criteria for the 2014 Bonus Shares had not been met; accordingly, the Company is marking to market the 2014 Bonus Shares expected to be earned and recording expense based on the aggregate fair value of the 2014 Bonus Shares at March 28, 2014.
	In March 2013, 21 executives of the Company, including Mr. Dolan, elected to receive their fiscal year 2013 bonuses (the "2013 Bonus"), if any were earned, in the form of shares of the Company's common stock (the "2013 Bonus Shares"). The 2013 Bonus Shares were granted on February 18, 2014 and vested immediately. The Company granted approximately one million 2013 Bonus Shares, with the number of shares granted calculated by dividing amounts equal to 1.5 times the respective 2013 Bonus amounts earned, as determined by the Compensation Committee, by $3.30, 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 from January 1, 2013 through the grant date. These shares are reported as both "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 fiscal 2012 in the form of restricted shares of the Company's common stock equal to 100% of their respective target bonus amounts for fiscal 2012 (the "Executive Bonus Shares"). The Executive Bonus Shares vested 50% on August 15, 2013 and the remaining 50% vested on February 15, 2014, contingent upon each such executive's continued employment with the Company on the last vesting date. The Company recorded the unamortized expense related to the Executive Bonus Shares as stock-based compensation expense through February 15, 2014. These shares are reported as "Vested" in the restricted stock grant table below.
	On August 7, 2012, Mr. Dolan elected to receive his fiscal year 2012 bonus, if earned, in the form of restricted shares of the Company's common stock (the “Dolan Bonus Shares”). The Dolan Bonus Shares vested 50% on August 15, 2013 and the remaining 50% vested on February 15, 2014. The Company recorded the unamortized stock-based compensation expense related to the Dolan Bonus Shares through February 15, 2014.
	On February 11, 2014, the Board of Directors increased its number of members from nine to eleven and elected Matthew W. Bross and Richard J. Lynch to the Board to fill the newly created directorships. In connection with their appointments, on February 18, 2014, each new director received a grant of shares of restricted stock with a grant date fair value of $100,000, with the number of shares granted calculated by dividing $100,000 by $3.30, the closing price of the Company's stock on the date of grant, and $100,000 of options to purchase the Company's common stock, with the number of shares calculated by dividing $100,000 by the grant date fair value of an option to purchase one share of common stock as determined by using the Black-Scholes valuation model. These awards will vest on the earlier of immediately prior to the Company's 2014 Annual Meeting of Stockholders or one year from the date of grant. Each of the new directors also elected to receive their 2014 annual retainers in shares of common stock in lieu of cash. Additionally, an incumbent member of the Board was appointed Chairman of a new committee and elected to receive his incremental retainer for this chairmanship in shares of the Company's common stock. All of the retainer shares were granted on February 18, 2014, with 50% vesting immediately and the remaining 50% to vest on July 1, 2014. The Company granted options to purchase approximately 135,000 shares of common stock and 88,000 shares of restricted common stock in the three months ended March 28, 2014 in connection with these actions. These stock options and restricted stock awards are reported as "Granted" in the respective tables below.
	Stock Options
	The activity related to the Company's outstanding stock options during the three months ended March 28, 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	33,136,112			$	3.22
	Granted	10,503,876			$	3.61
	PT outstanding options converted to Sonus options	1,283,058			$	1.73
	Exercised	(1,353,598	)		$	2.55
	Forfeited	(486,481	)		$	2.82
	Expired	(323,308	)		$	5.46
	Outstanding at March 28, 2014	42,759,659			$	3.28			7.4	$	16,351
	Vested or expected to vest at March 28, 2014	40,387,215			$	3.31			7.33	$	15,090
	Exercisable at March 28, 2014	16,298,327			$	3.55			4.79	$	7,859
	The grant date fair values of options to purchase common stock granted in the three months ended March 28, 2014 were estimated using the Black-Scholes valuation model with the following assumptions:
		Three months ended
		March 28,
		2014
	Risk-free interest rate	1.53% - 2.70%
	Expected dividends	—
	Weighted average volatility	61.70%
	Expected life (years)	4.5 - 6.0
	Additional information regarding the Company's stock options for the three months ended March 28, 2014 is as follows:
			Three months ended
			March 28,
			2014
	Weighted average grant date fair value of stock options granted		$	1.66
	Total intrinsic value of stock options exercised (in thousands)		$	1,589
	Cash received from the exercise of stock options (in thousands)		$	3,444
	Restricted Stock Awards
	The activity related to the Company's unvested restricted stock awards for the three months ended March 28, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
	Unvested balance at January 1, 2014	1,238,765			$	2.82
	Granted	1,410,299			$	3.25
	Vested	(1,385,542	)		$	3.16
	Forfeited	—			$	—
	Unvested balance at March 28, 2014	1,263,522			$	2.92
	The total fair value of shares of restricted stock that vested during the three months ended March 28, 2014 was $4.4 million.
	Performance-Based Stock Awards
	The activity related to the Company's performance-based stock awards for the three months ended March 28, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
Unvested balance at January 1, 2014	1,059,541			$	2.6
Granted	—			$	—
Vested	(367,004	)		$	2.6
Forfeited	—			$	—
Unvested balance at March 28, 2014	692,537			$	2.72
Employee Stock Purchase Plan
At the February 2014 meeting of the Board of Directors, the ESPP was amended, effective March 1, 2014, to provide for six-month 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 2,500, subject to certain adjustments pursuant to the ESPP.
Stock-Based Compensation
The condensed consolidated statements of operations include stock-based compensation for the three months ended March 28, 2014 and March 29, 2013 as follows (in thousands):
		Three months ended
		March 28,				March 29,
		2014				2013
Product cost of revenue		$	79			$	52
Service cost of revenue		279				210
Research and development		1,313				679
Sales and marketing		1,249				1,099
General and administrative		2,854				2,184
		$	5,774			$	4,224
There is no income tax benefit for employee stock-based compensation expense for the three months ended March 28, 2014 or March 29, 2013 due to the valuation allowance recorded.
At March 28, 2014, there was $42.3 million, net of expected forfeitures, of unrecognized stock-based compensation expense related to unvested stock options and restricted stock awards. This expense is expected to be recognized over a weighted average period of approximately three years.

MAJOR_CUSTOMERS

MAJOR CUSTOMERS	3 Months Ended
	Mar. 28, 2014
Risks and Uncertainties [Abstract]	'
MAJOR CUSTOMERS	'
	MAJOR CUSTOMERS
	The following customers each contributed 10% or more of the Company's revenue in at least one of the three month periods ended March 28, 2014 and March 29, 2013:
		Three months ended
		March 28,	March 29,
		2014	2013
	AT&T Inc.	28%	11%
	United States Government	*	16%
	__________________________________
	* Represents less than 10% of revenue
	At March 28, 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_INFORMATION

GEOGRAPHIC INFORMATION	3 Months Ended
	Mar. 28, 2014
Segment Reporting [Abstract]	'
GEOGRAPHIC INFORMATION	'
	GEOGRAPHIC INFORMATION
	The Company's classification of revenue by geographic area is determined by the location to which the product is shipped or where the services are performed. The following table summarizes revenue by geographic area as a percentage of total revenue:
		Three months ended
		March 28,		March 29,
		2014		2013
	United States	73	%	69	%
	Europe, Middle East and Africa	13		10
	Japan	8		16
	Other Asia Pacific	3		4
	Other	3		1
		100	%	100	%
	International revenue, both as a percentage of total revenue and absolute dollars, may vary from one period to the next, and accordingly, historical data may not be indicative of future periods.

INCOME_TAXES

INCOME TAXES	3 Months Ended
	Mar. 28, 2014
Income Tax Disclosure [Abstract]	'
INCOME TAXES	'
	INCOME TAXES
	The Company's income tax provisions for the three months ended March 28, 2014 and March 29, 2013 reflect the Company's estimates of the effective rates expected to be applicable for the respective full years, adjusted for any discrete events, which are recorded in the period that they occur. These estimates are reevaluated each quarter based on the Company's estimated tax expense for the full year. The estimated effective rates for the three months ended March 28, 2014 and March 29, 2013 do not include any benefit for the Company's domestic losses, as the Company has concluded that a valuation allowance on any domestic benefit is required.
	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. The Company is currently assessing these rules and the impact they will have on its consolidated financial statements, if any.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 28, 2014
Commitments and Contingencies Disclosure [Abstract]	'
COMMITMENTS AND CONTINGENCIES	'
	COMMITMENTS 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 applicable 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.

BASIS_OF_PRESENTATION_Policies

BASIS OF PRESENTATION (Policies)	3 Months Ended
	Mar. 28, 2014
Accounting Policies [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments, consisting only of normal recurring items, necessary for their fair presentation with accounting principles generally accepted in the United States of America ("GAAP") and with the rules and regulations of the U.S. Securities and Exchange Commission ("SEC").
	Interim results are not necessarily indicative of results for a full year or any future interim period. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company's Annual Report on Form 10-K for the year ended December 31, 2013 ("Annual Report") filed with the SEC effective February 28, 2014.
	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 condensed consolidated financial statements for the three months ended March 28, 2014 for the period subsequent to the PT Acquisition Date.
Principles of Consolidation	'
	Principles of Consolidation
	The condensed consolidated financial statements include the accounts of Sonus and its wholly-owned subsidiaries. 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, including impairments, 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.
Financial Instruments	'
	Fair Value of Financial Instruments
	The carrying amounts of the Company's financial instruments, which include cash equivalents, marketable securities, investments, accounts receivable, accounts payable, convertible subordinated debt and other long-term liabilities, approximate their fair values.
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.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	On July 18, 2013, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("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 condensed consolidated financial statements, as the Company already applied the methodology prescribed by ASU 2013-11.
	On March 4, 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 condensed consolidated financial statements.

ACQUISITION_OF_PT_Tables

ACQUISITION OF PT (Tables)	3 Months Ended
	Mar. 28, 2014
Business Combinations [Abstract]	'
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	$	34,010
	Unpaid purchase consideration	1,012
	Fair value of equity awards assumed	1,671
	Fair value of total consideration	$	36,693
	Fair value of assets acquired and liabilities assumed:
	Marketable securities	$	2,315
	Other current assets	9,696
	Property and equipment	2,251
	Intangible assets	17,100
	Goodwill	8,193
	Current liabilities	(2,762		)
	Other long-term liabilities	(100		)
		$	36,693
Schedule of Components of Acquisition Related Costs	'
	The components of acquisition-related costs included in the Company's results of operations for the three months ended March 28, 2014 are as follows (in thousands):
	Professional and services fees	$	1,057
	Change of control agreements	249
		$	1,306

EARNINGS_LOSS_PER_SHARE_Tables

EARNINGS (LOSS) PER SHARE (Tables)	3 Months Ended
	Mar. 28, 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):
		Three months ended
		March 28,	March 29,
		2014	2013
	Weighted average shares outstanding—basic	265,400	281,542
	Potential dilutive common shares	—	—
	Weighted average shares outstanding—diluted	265,400	281,542

CASH_EQUIVALENTS_MARKETABLE_SE1

CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS (Tables)	3 Months Ended
	Mar. 28, 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 marketable debt and equity securities and investments at March 28, 2014 and December 31, 2013 were comprised of the following (in thousands):
		28-Mar-14
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	10,363	$	—	$	—		$	10,363
	Marketable securities
	U.S. government agency notes	$	20,796	$	4	$	(1	)	$	20,799
	Corporate debt securities	63,597		11		(11		)	63,597
	Commercial paper	1,250		—		—			1,250
	Certificates of deposit	1,800		—		—			1,800
		$	87,443	$	15	$	(12	)	$	87,446
		31-Dec-13
		Amortized		Unrealized		Unrealized			Fair
		cost		gains		losses			value
	Cash equivalents	$	50,404	$	—	$	—		$	50,404
	Marketable securities
	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 March 28, 2014 and December 31, 2013. These financial assets are comprised of the Company's available-for-sale debt and equity securities and reported under the captions Cash and cash equivalents, Marketable securities and Investments in the consolidated balance sheets (in thousands):
				Fair value measurements at
				March 28, 2014 using:
		Total carrying		Quoted prices		Significant other			Significant
		value at		in active		observable			unobservable
		March 28,		markets		inputs			inputs
		2014		(Level 1)		(Level 2)			(Level 3)
	Cash equivalents	$	10,363	$	10,363	$	—		$	—
	Marketable securities
	U.S. government agency notes	$	20,799	$	—	$	20,799		$	—
	Corporate debt securities	63,597		—		63,597			—
	Commercial paper	1,250		—		1,250			—
	Certificates of deposit	1,800		—		1,800			—
		$	87,446	$	—	$	87,446		$	—
				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	$	—		$	—
	Marketable securities
	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		$	—

INVENTORY_Tables

INVENTORY (Tables)	3 Months Ended
	Mar. 28, 2014
Inventory Disclosure [Abstract]	'
Schedule of inventory	'
	Inventory consists of the following (in thousands):
		March 28,			December 31,
		2014			2013
	Raw materials	$	968		$	—
	On-hand final assemblies and finished goods inventories	19,737			19,070
	Deferred cost of goods sold	4,056			4,387
		24,761			23,457
	Less current portion	(24,178		)	(21,793		)
	Noncurrent portion (included in Other assets)	$	583		$	1,664

INTANGIBLE_ASSETS_AND_GOODWILL1

INTANGIBLE ASSETS AND GOODWILL (Tables)	3 Months Ended
	Mar. 28, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of intangible assets	'
	The Company's intangible assets at March 28, 2014 and December 31, 2013 consist of the following (dollars in thousands):
	March 28, 2014	Weighted average amortization period		Cost				Accumulated			Net
		(years)						amortization			carrying value
	Intellectual property	5		$	999			$	999		$	—
	Developed technology	6.18		22,280				3,299			18,981
	Customer relationships	5.57		10,040				3,204			6,836
	Internal use software	3		730				385			345
		5.75		$	34,049			$	7,887		$	26,162
	December 31, 2013	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 three months ended March 28, 2014 and March 29, 2013 was as follows (in thousands):
		Three months ended								Statement of operations classification
		March 28,				March 29,
		2014				2013
	Intellectual property	$	—			$	100			Research and development
	Developed technology	570				500				Cost of revenue - product
	Customer relationships	398				526				Sales and marketing
	Internal use software	61				61				Cost of revenue - product
		$	1,029			$	1,187
Schedule of estimated future amortization expense for intangible assets	'
	Estimated future amortization expense for the Company's intangible assets at March 28, 2014 is as follows (in thousands):
	Years ending December 31,
	Remainder of 2014	$	3,568
	2015	5,647
	2016	5,290
	2017	5,259
	2018	2,953
	Thereafter	3,445
		$	26,162
Schedule of goodwill	'
	The changes in the carrying value of the Company's goodwill in the three months ended March 28, 2014 were as follows (in thousands):
	Balance at January 1, 2014:
	Goodwill	$	35,485
	Accumulated impairment losses	(3,106		)
		32,379
	Acquisition of PT	8,193
	Balance at March 28, 2014	$	40,572
	There were no changes to the carrying value of the Company's goodwill in the three months ended March 29, 2013.

ACCRUED_EXPENSES_Tables

ACCRUED EXPENSES (Tables)	3 Months Ended
	Mar. 28, 2014
Payables and Accruals [Abstract]	'
Schedule of accrued expenses	'
	Accrued expenses consist of the following (in thousands):
		March 28,		December 31,
		2014		2013
	Employee compensation and related costs	$	11,692	$	20,683
	Other	13,997		13,343
		$	25,689	$	34,026

RESTRUCTURING_ACCRUAL_Tables

RESTRUCTURING ACCRUAL (Tables)	3 Months Ended
	Mar. 28, 2014
Restructuring and Related Activities [Abstract]	'
Summary of restructuring accrual activity	'
	The table below summarizes the restructuring accrual activity for the three months ended March 28, 2014 (in thousands):
		Balance at		Initiatives		Cash			Balance at
		January 1,		charged to		payments			March 28,
		2014		expense					2014
	Severance	$	1,333	$	1,169	$	(1,394	)	$	1,108
	Facilities	3,012		—		(295		)	2,717
		$	4,345	$	1,169	$	(1,689	)	$	3,825

STOCKBASED_COMPENSATION_PLANS_

STOCK-BASED COMPENSATION PLANS (Tables)	3 Months Ended
	Mar. 28, 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 three months ended March 28, 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	33,136,112			$	3.22
	Granted	10,503,876			$	3.61
	PT outstanding options converted to Sonus options	1,283,058			$	1.73
	Exercised	(1,353,598	)		$	2.55
	Forfeited	(486,481	)		$	2.82
	Expired	(323,308	)		$	5.46
	Outstanding at March 28, 2014	42,759,659			$	3.28			7.4	$	16,351
	Vested or expected to vest at March 28, 2014	40,387,215			$	3.31			7.33	$	15,090
	Exercisable at March 28, 2014	16,298,327			$	3.55			4.79	$	7,859
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 three months ended March 28, 2014 were estimated using the Black-Scholes valuation model with the following assumptions:
		Three months ended
		March 28,
		2014
	Risk-free interest rate	1.53% - 2.70%
	Expected dividends	—
	Weighted average volatility	61.70%
	Expected life (years)	4.5 - 6.0
Schedule of stock options, additional information	'
	Additional information regarding the Company's stock options for the three months ended March 28, 2014 is as follows:
			Three months ended
			March 28,
			2014
	Weighted average grant date fair value of stock options granted		$	1.66
	Total intrinsic value of stock options exercised (in thousands)		$	1,589
	Cash received from the exercise of stock options (in thousands)		$	3,444
Schedule of activity related to unvested restricted stock grants	'
	The activity related to the Company's unvested restricted stock awards for the three months ended March 28, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
	Unvested balance at January 1, 2014	1,238,765			$	2.82
	Granted	1,410,299			$	3.25
	Vested	(1,385,542	)		$	3.16
	Forfeited	—			$	—
	Unvested balance at March 28, 2014	1,263,522			$	2.92
Schedule of activity related to performance stock awards	'
	The activity related to the Company's performance-based stock awards for the three months ended March 28, 2014 is as follows:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
	Unvested balance at January 1, 2014	1,059,541			$	2.6
	Granted	—			$	—
	Vested	(367,004	)		$	2.6
	Forfeited	—			$	—
	Unvested balance at March 28, 2014	692,537			$	2.72
Schedule of stock-based compensation expenses which are included in condensed consolidated statement of operations	'
	The condensed consolidated statements of operations include stock-based compensation for the three months ended March 28, 2014 and March 29, 2013 as follows (in thousands):
			Three months ended
			March 28,				March 29,
			2014				2013
	Product cost of revenue		$	79			$	52
	Service cost of revenue		279				210
	Research and development		1,313				679
	Sales and marketing		1,249				1,099
	General and administrative		2,854				2,184
			$	5,774			$	4,224

MAJOR_CUSTOMERS_Tables

MAJOR CUSTOMERS (Tables)	3 Months Ended
	Mar. 28, 2014
Risks and Uncertainties [Abstract]	'
Schedule of customers contributing 10% or more of the revenue	'
	The following customers each contributed 10% or more of the Company's revenue in at least one of the three month periods ended March 28, 2014 and March 29, 2013:
		Three months ended
		March 28,	March 29,
		2014	2013
	AT&T Inc.	28%	11%
	United States Government	*	16%
	__________________________________
	* Represents less than 10% of revenue

GEOGRAPHIC_INFORMATION_Tables

GEOGRAPHIC INFORMATION (Tables)	3 Months Ended
	Mar. 28, 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 to which the product is shipped or where the services are performed. The following table summarizes revenue by geographic area as a percentage of total revenue:
		Three months ended
		March 28,		March 29,
		2014		2013
	United States	73	%	69	%
	Europe, Middle East and Africa	13		10
	Japan	8		16
	Other Asia Pacific	3		4
	Other	3		1
		100	%	100	%

BASIS_OF_PRESENTATION_Narrativ

BASIS OF PRESENTATION - Narrative (Details)	3 Months Ended
	Mar. 28, 2014
	segment
Accounting Policies [Abstract]	'
Number of reportable operating segments	1

ACQUISITION_OF_PT_Details

ACQUISITION OF PT - (Details) (USD $)	3 Months Ended					0 Months Ended	3 Months Ended
	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013	Sep. 28, 2012	Dec. 31, 2011	Feb. 19, 2014	Mar. 28, 2014
						PT [Member]	PT [Member]
Acquisition Of Net	'	'	'	'	'	'	'
Cash consideration	'	'	'	'	'	$34,000,000	'
Cash consideration per share of the acquired entity (in dollars per share)	'	'	'	'	'	$3.75	'
Period over which goodwill will be deductible for tax purpose	'	'	'	'	'	'	'15 years
Fair value of consideration transferred:	'	'	'	'	'	'	'
Cash, net of cash acquired	34,010,000	0	'	'	'	34,010,000	'
Unpaid purchase consideration	'	'	'	'	'	1,012,000	'
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	'	'	'	'	'	9,696,000	'
Property and equipment	'	'	'	'	'	2,251,000	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	'	'	'	'	'	17,100,000	'
Goodwill	40,572,000	'	32,379,000	40,572,000	32,379,000	8,193,000	'
Current liabilities	'	'	'	'	'	-2,762,000	'
Other long-term liabilities	'	'	'	'	'	-100,000	'
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	'	'	'	'	'	36,693,000	'
Professional Fees	'	'	'	'	'	'	1,057,000
Change of Control Agreements	'	'	'	'	'	'	249,000
Acquisition-related	$1,306,000	$0	'	'	'	'	$1,306,000

EARNINGS_LOSS_PER_SHARE_Detail

EARNINGS (LOSS) PER SHARE - (Details)	3 Months Ended
	Mar. 28, 2014	Mar. 29, 2013
Reconciliation of weighted average shares outstanding from basic to diluted	'	'
Weighted average shares outstanding - basic	265,400,000	281,542,000
Potential dilutive common shares	0	0
Weighted average shares outstanding - diluted	265,400,000	281,542,000
Common stock and unvested shares of restricted stock not included because their effect would have been antidilutive (in shares)	45,300,000	31,500,000

CASH_EQUIVALENTS_MARKETABLE_SE2

CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS - Narrative (Details) (USD $)	3 Months Ended
	Mar. 28, 2014
Schedule of Available-for-sale Securities [Line Items]	'
Available-for-sale securities sold	$45,900,000
Available-for-sale securities, gross realized gains	46,000
Proceeds from maturities of available-for-sale securities	$41,700,000
Minimum [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Period considered to classify available-for-sale securities as investments	'1 year
Maximum [Member]	'
Schedule of Available-for-sale Securities [Line Items]	'
Period considered to classify available-for-sale securities as investments	'2 years

CASH_EQUIVALENTS_MARKETABLE_SE3

CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS - Schedule of Activity for Short-Term Investments (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Amortized cost, gross unrealized gains and losses and fair value of marketable debt and equity securities and investments	'	'
Cash equivalents, amortized cost	$10,363	$50,404
Cash equivalents, fair value	10,363	50,404
Marketable securities, amortized cost	87,443	138,835
Marketable securities, unrealized gains	15	55
Marketable securities, unrealized losses	-12	-8
Marketable securities, fair value	87,446	138,882
Investments, amortized cost	'	34,352
Investments, unrealized gains	'	20
Investments, unrealized losses	'	-8
Investments, fair value	0	34,364
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	20,796	47,895
Marketable securities, unrealized gains	4	15
Marketable securities, unrealized losses	-1	0
Marketable securities, fair value	20,799	47,910
Investments, amortized cost	'	9,254
Investments, unrealized gains	'	3
Investments, unrealized losses	'	0
Investments, fair value	'	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	63,597	81,993
Marketable securities, unrealized gains	11	35
Marketable securities, unrealized losses	-11	-8
Marketable securities, fair value	63,597	82,020
Investments, amortized cost	'	23,848
Investments, unrealized gains	'	17
Investments, unrealized losses	'	-8
Investments, fair value	'	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	1,250	5,647
Marketable securities, unrealized gains	0	2
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	1,250	5,649
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	1,800	3,300
Marketable securities, unrealized gains	0	3
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	$1,800	$3,303

CASH_EQUIVALENTS_MARKETABLE_SE4

CASH EQUIVALENTS, MARKETABLE SECURITIES AND INVESTMENTS - Schedule of Short-Term Investments by Measurement (Detail) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Cash and cash equivalents, Marketable securities and Investments	'	'
Cash equivalents, fair value	$10,363	$50,404
Marketable securities, fair value	87,446	138,882
Investments, fair value	0	34,364
Total carrying value [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Cash equivalents, fair value	10,363	50,404
Marketable securities, fair value	87,446	138,882
Investments, fair value	'	34,364
Quoted prices in active markets (Level 1) [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Cash equivalents, fair value	10,363	50,404
Marketable securities, fair value	0	0
Investments, fair value	'	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	87,446	138,882
Investments, fair value	'	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
U.S. government agency notes [Member] | Total carrying value [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	20,799	47,910
Investments, fair value	'	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
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	20,799	47,910
Investments, fair value	'	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
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	63,597	82,020
Investments, fair value	'	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
Corporate debt securities [Member] | Significant other observable inputs (Level 2) [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	63,597	82,020
Investments, fair value	'	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
Commercial paper [Member] | Total carrying value [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	1,250	5,649
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
Commercial paper [Member] | Significant other observable inputs (Level 2) [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	1,250	5,649
Commercial paper [Member] | Significant unobservable inputs (Level 3) [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	0	0
Certificates of deposit [Member] | Total carrying value [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	1,800	3,303
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
Certificates of deposit [Member] | Significant other observable inputs (Level 2) [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	1,800	3,303
Certificates of deposit [Member] | Significant unobservable inputs (Level 3) [Member]	'	'
Cash and cash equivalents, Marketable securities and Investments	'	'
Marketable securities, fair value	$0	$0

INVENTORY_Details

INVENTORY - (Details) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw materials	$968	$0
On-hand final assemblies and finished goods inventories	19,737	19,070
Deferred cost of goods sold	4,056	4,387
Gross inventory	24,761	23,457
Less current portion	-24,178	-21,793
Noncurrent portion (included in other assets)	$583	$1,664

INTANGIBLE_ASSETS_AND_GOODWILL2

INTANGIBLE ASSETS AND GOODWILL - (Details) (USD $)	3 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013	Dec. 31, 2011
Intangible Assets And Goodwill	'	'	'	'
Goodwill, Gross	'	'	'	$35,485
Goodwill, Impaired, Accumulated Impairment Loss	'	'	'	3,106
Weighted average amortization period (years)	'5 years 9 months	'	'4 years 4 months 6 days	'
Cost	34,049	'	16,949	'
Accumulated amortization	7,887	'	6,858	'
Net carrying value	26,162	'	10,091	'
Amortization expense	1,029	1,187	'	'
Estimated future amortization expense for intangible assets	'	'	'	'
2013	3,568	'	'	'
2014	5,647	'	'	'
2015	5,290	'	'	'
2016	5,259	'	'	'
2017	2,953	'	'	'
Thereafter	3,445	'	'	'
Total	26,162	'	'	'
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	100	'	'
Developed technology [Member]	'	'	'	'
Intangible Assets And Goodwill	'	'	'	'
Weighted average amortization period (years)	'6 years 2 months 5 days	'	'5 years 0 months 11 days	'
Cost	22,280	'	9,080	'
Accumulated amortization	3,299	'	2,729	'
Net carrying value	18,981	'	6,351	'
Amortization expense	570	500	'	'
Customer relationships [Member]	'	'	'	'
Intangible Assets And Goodwill	'	'	'	'
Weighted average amortization period (years)	'5 years 6 months 26 days	'	'5 years 3 months 18 days	'
Cost	10,040	'	6,140	'
Accumulated amortization	3,204	'	2,806	'
Net carrying value	6,836	'	3,334	'
Amortization expense	398	526	'	'
Internal use software [Member]	'	'	'	'
Intangible Assets And Goodwill	'	'	'	'
Weighted average amortization period (years)	'3 years	'	'3 years	'
Cost	730	'	730	'
Accumulated amortization	385	'	324	'
Net carrying value	345	'	406	'
Amortization expense	$61	$61	'	'

INTANGIBLE_ASSETS_AND_GOODWILL3

INTANGIBLE ASSETS AND GOODWILL - (Details 2) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 29, 2013	Mar. 28, 2014	Dec. 31, 2013	Sep. 28, 2012	Dec. 31, 2011
Goodwill [Roll Forward]	'	'	'	'	'
Goodwill	'	'	'	'	$35,485
Accumulated impairment losses	'	'	'	'	-3,106
Goodwill, beginning of period	'	40,572	32,379	40,572	32,379
Acquisition of PT	8,193	'	'	'	'
Goodwill, end of period	'	$40,572	$32,379	$40,572	$32,379

ACCRUED_EXPENSES_Details

ACCRUED EXPENSES - (Details) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables and Accruals [Abstract]	'	'
Employee compensation and related costs	$11,692	$20,683
Other	13,997	13,343
Total	$25,689	$34,026

RESTRUCTURING_ACCRUAL_Details

RESTRUCTURING ACCRUAL - (Details) (USD $)	3 Months Ended
	Mar. 28, 2014	Mar. 29, 2013	Dec. 31, 2013
RESTRUCTURING ACCRUAL	'	'	'
Accrued restructuring	$1,800,000	'	$1,800,000
Restructuring Reserve [Roll Forward]	'	'	'
Restructuring	1,169,000	1,949,000	'
Employee Severance [Member]	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'
Balance at the beginning of the period	1,333,000	'	'
Restructuring	1,169,000	1,900,000	'
Cash payments	-1,394,000	'	'
Balance at the end of the period	1,108,000	'	'
Facilities [Member]	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'
Balance at the beginning of the period	3,012,000	'	'
Restructuring	0	'	'
Cash payments	-295,000	'	'
Balance at the end of the period	2,717,000	'	'
Employee Severance and Facilities [Member]	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'
Balance at the beginning of the period	4,345,000	'	'
Restructuring	1,169,000	'	'
Cash payments	-1,689,000	'	'
Balance at the end of the period	$3,825,000	'	'

DEBT_Details

DEBT - (Details) (USD $)	Mar. 28, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Disclosure [Abstract]	'	'
Aggregate principal amounts remaining outstanding	$2,380	$2,380

STOCKHOLDER_RIGHTS_PLAN_Detail

STOCKHOLDER RIGHTS PLAN (Details)	Mar. 28, 2014	Jun. 26, 2013
Class of Warrant or Right [Line Items]	'	'
Minimum percentage of ownership for rights to be exercisable	'	15.00%
Preferred Stock [Member]	'	'
Class of Warrant or Right [Line Items]	'	'
Dividend of right per common stock	'	1
Share of preferred stock issued upon conversion	'	0.001
Exerice price per right	25	'

COMMON_STOCK_REPURCHASES_AND_U1

COMMON STOCK REPURCHASES AND UNDERWRITTEN OFFERING (Details) (USD $)	0 Months Ended	3 Months Ended		0 Months Ended	3 Months Ended
	Mar. 20, 2014	Mar. 28, 2014	Mar. 29, 2013	Jul. 29, 2013	Mar. 28, 2014
				Common Stock [Member]	Stock Buyback Program [Member]
Class of Stock [Line Items]	'	'	'	'	'
Stock buyback program authorized amount	'	'	'	$100,000,000	'
Payments for repurchase of common stock	'	75,385,000	0	'	144,000
Stock Repurchased and Retired During Period, Shares	'	38,500	'	'	'
Stock Repurchase Program, Remaining Authorized Repurchase Amount	'	40,600,000	'	'	'
Stock Issued During Period, Shares, New Issues	37,500,000	'	'	'	'
Over-allotment Option Period	'30 days	'	'	'	'
Stock Issued During Period, Shares, New Issues, Over-Allotment Option	5,625,000	'	'	'	'
Stock Repurchased During Period, Shares	21,500,000	'	'	'	'
Stock Repurchased During Period, Price Per Share	$3.49	'	'	'	'
Transaction Fees	$300,000	'	'	'	'

STOCKBASED_COMPENSATION_PLANS_1

STOCK-BASED COMPENSATION PLANS - (Details) (USD $)

0 Months Ended

1 Months Ended

3 Months Ended

3 Months Ended

1 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

1 Months Ended

Feb. 18, 2014

Jan. 22, 2014

Feb. 15, 2013

Feb. 10, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 28, 2014

Mar. 29, 2013

Feb. 19, 2014

Jan. 02, 2014

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 28, 2014

Mar. 29, 2013

Mar. 29, 2013

Feb. 18, 2014

Feb. 19, 2014

Mar. 28, 2014

Feb. 18, 2014

Feb. 18, 2014

Mar. 28, 2014

Mar. 28, 2014

Feb. 19, 2014

Mar. 28, 2014

Mar. 28, 2014

Mar. 28, 2014

Jan. 02, 2014

Feb. 15, 2013

Mar. 28, 2014

Mar. 28, 2014

executives

executives

executives

executives

executives

Product cost of revenue [Member]

Product cost of revenue [Member]

Service cost of revenue [Member]

Service cost of revenue [Member]

Research and development [Member]

Research and development [Member]

Sales and marketing [Member]

Sales and marketing [Member]

General and Administrative Expense [Member]

General and Administrative Expense [Member]

Raymond P. Dolan, President and Chief Executive Officer [Member]

Matthew W. Bross and Richard J. Lynch [Member]

Matthew W. Bross and Richard J. Lynch [Member]

Matthew W. Bross and Richard J. Lynch [Member]

Immediately Vest [Member]

Vest July 1, 2014 [Member]

Minimum [Member]

Maximum [Member]

PT [Member]

PT [Member]

Stock options [Member]

Restricted stock awards [Member]

Restricted stock awards [Member]

Performance share awards [Member]

Performance share awards [Member]

Employee Stock [Member]

Matthew W. Bross and Richard J. Lynch [Member]

Matthew W. Bross and Richard J. Lynch [Member]

Raymond P. Dolan, President and Chief Executive Officer [Member]

Stock-based compensation

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation by Share-based Payment Award, Offering Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'6 months

Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

85.00%

Business Combination, Consideration Transferred, Equity Interests Issued and Issuable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1,671,000

'

'

'

'

'

'

'

Number of executives

'

21

8

9

21

11

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Executives Electing to Receive Cash Bonus

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation by Share-based Payment Award, Stock Percentage of Award

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Salary Base to Calculate Shares Granted

'

150.00%

'

'

150.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

150.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of bonus received as common stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

Award vesting percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50.00%

50.00%

'

'

'

'

'

'

'

50.00%

'

'

Conversion factor used to convert a number of shares available for grant into the entity's equity awards

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.23

'

'

'

'

'

'

Share Price

'

'

'

'

'

'

'

'

$3.30

$3.08

'

'

'

'

'

'

'

'

'

'

'

'

$3.30

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation by Share-based Payment Award, Cash Percentage of Award

'

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Executives Electing to Receive Stock Bonus

'

17

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Business Acquisition, Share Price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.75

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Base to Calculate Shares Granted

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Total fair value (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,400,000

'

'

'

'

Stock-based compensation (in dollars)

'

'

'

'

'

'

5,774,000

4,224,000

'

'

79,000

52,000

279,000

210,000

1,313,000

679,000

1,249,000

1,099,000

2,854,000

2,184,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of the assumed awards attributable to future stock-based compensation expense

'

'

'

'

'

42,300,000

42,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

900,000

'

'

'

'

'

'

'

Expected period for unrecognized expense

'

'

'

'

'

'

'3 years

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'1 year

'

'

'

'

'

'

'

Stock Granted, Value, Share-based Compensation, Net of Forfeitures

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the beginning of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

33,136,112

'

'

'

'

'

Granted (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

135,000

'

'

'

'

'

'

10,503,876

'

'

'

'

'

PT outstanding options converted to Sonus options (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,283,058

'

'

'

'

'

Exercised (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,353,598

'

'

'

'

'

Forfeited (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-486,481

'

'

'

'

'

Expired (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-323,308

'

'

'

'

'

Outstanding at the end of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

42,759,659

'

'

'

'

'

Vested or expected to vest at the end of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40,387,215

'

'

'

'

'

Exercisable at the end of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

16,298,327

'

'

'

'

'

Weighted average exercise price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the beginning of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.22

'

'

'

'

'

Granted (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.61

'

'

'

'

'

PT outstanding options converted to Sonus options (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1.73

'

'

'

'

'

Exercised (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2.55

'

'

'

'

'

Forfeited (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2.82

'

'

'

'

'

Expired (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$5.46

'

'

'

'

'

Outstanding at the end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.28

'

'

'

'

'

Vested or expected to vest at the end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.31

'

'

'

'

'

Exercisable at the end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.55

'

'

'

'

'

Weighted average remaining contractual life (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the end of the period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'7 years 4 months 24 days

'

'

'

'

'

Vested or expected to vest at the end of the period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'7 years 3 months 29 days

'

'

'

'

'

Exercisable at the end of the period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 years 9 months 15 days

'

'

'

'

'

Aggregate intrinsic value (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at the end of the period (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

16,351,000

'

'

'

'

'

Vested or expected to vest at the end of the period (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

15,090,000

'

'

'

'

'

Exercisable at the end of the period (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,859,000

'

'

'

'

'

Range of assumptions used in estimating fair value of options

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Risk-free interest rates, minimum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.53%

'

'

'

'

'

Risk-free interest rates, maximum

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2.70%

'

'

'

'

'

Expected dividends

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.00%

'

'

'

'

'

Weighted average volatility

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

61.70%

'

'

'

'

'

Expected life

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 years 6 months

'6 years

'

'

'

'

'

'

'

'

Weighted average grant date fair value of stock options granted (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1.66

'

'

'

'

'

Total intrinsic values of stock options exercised (in dollars)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,589,000

'

'

'

'

'

Cash received from the exercise of stock options (in dollars)

'

'

'

'

'

'

$3,444,000

$578,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3,444,000

'

'

'

'

'

Change in unvested restricted stock awards

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unvested balance at the beginning of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,238,765

'

'

1,059,541

'

Granted (in shares)

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

88,000

'

'

'

'

'

'

'

1,410,299

243,507

'

0

'

Vested (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,385,542

'

'

-367,004

'

Forfeited (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0

'

'

0

'

Unvested balance at the end of the period (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,263,522

'

'

692,537

'

Weighted average grant-date fair value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unvested balance at the end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2.82

'

'

$2.60

'

Granted (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$100,000

'

'

'

'

'

'

'

'

'

$3.25

'

'

$0

'

Vested (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$3.16

'

'

$2.60

'

Forfeited (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0

'

'

$0

'

Unvested balance at end of the period (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2.92

'

'

$2.72

'

Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'1 year

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,500

MAJOR_CUSTOMERS_Details

MAJOR CUSTOMERS - (Details)	3 Months Ended
	Mar. 28, 2014	Mar. 28, 2014	Mar. 29, 2013	Mar. 29, 2013	Mar. 28, 2014	Mar. 29, 2013	Mar. 28, 2014	Dec. 31, 2013
	Revenue [Member]	Revenue [Member]	Revenue [Member]	Revenue [Member]	Accounts receivable balance [Member]	Accounts receivable balance [Member]	Accounts receivable balance [Member]	Accounts receivable balance [Member]
	Less than [Member]	Customer [Member]	Customer [Member]	Customer [Member]		Customer [Member]	Customer [Member]	Customer [Member]
		AT&T [Member]	AT&T [Member]	United States [Member]			customer	customer
MAJOR CUSTOMERS	'	'	'	'	'	'	'	'
Concentration risk, percentage	'	28.00%	11.00%	16.00%	'	13.00%	'	'
Number of major customers	'	'	'	'	'	'	0	1
Threshold percentage	10.00%	'	'	'	10.00%	'	'	'

GEOGRAPHIC_INFORMATION_Summary

GEOGRAPHIC INFORMATION - Summary of Revenue by Geographic Area as a Percentage of Total Revenue (Details) (Revenue [Member], Geographical area [Member])	3 Months Ended
	Mar. 28, 2014	Mar. 29, 2013
Revenue by geographic area and by customer	'	'
Percentage of total revenue	100.00%	100.00%
United States [Member]	'	'
Revenue by geographic area and by customer	'	'
Percentage of total revenue	73.00%	69.00%
Europe, Middle East and Africa [Member]	'	'
Revenue by geographic area and by customer	'	'
Percentage of total revenue	13.00%	10.00%
Japan [Member]	'	'
Revenue by geographic area and by customer	'	'
Percentage of total revenue	8.00%	16.00%
Other Asia Pacific [Member]	'	'
Revenue by geographic area and by customer	'	'
Percentage of total revenue	3.00%	4.00%
Other [Member]	'	'
Revenue by geographic area and by customer	'	'
Percentage of total revenue	3.00%	1.00%