Results Include $87.3 Million Non-cash Charge for Deferred Tax Valuation Allowance

Westford, MA, February 26, 2009 – Sonus Networks, Inc. (Nasdaq: SONS), a market leader in IP communications infrastructure, today announced results for the fourth quarter and full year ended December 31, 2008.

Revenue from continuing operations for the fourth quarter of fiscal 2008 was $89.5 million, compared to $62.2 million in the third quarter of fiscal 2008 and $97.1 million for the fourth quarter of fiscal 2007.  The Company's loss from continuing operations on a GAAP basis was $99.0 million, or $0.37 per share, for the fourth quarter of 2008, compared to a loss from continuing operations of $19.0 million, or $0.07 per share, for the third quarter of 2008, and income from continuing operations of $14.7 million, or $0.05 per share, for the fourth quarter of 2007.

Revenue from continuing operations for the full year 2008 was $313.1 million, compared to $319.4 million last year, a decrease of $6.3 million year over year.  The Company's loss from continuing operations on a GAAP basis was $113.6 million, or $0.42 per share, compared to a loss from continuing operations of $22.6 million, or $0.09 per share, in fiscal 2007.

Included in both the fourth quarter and full year 2008 results is an $87.3 million non-cash charge related to an increase in the Company's valuation allowance against its deferred tax asset.

"We continue to make progress on aligning the business to our market opportunity," said Richard Nottenburg, president and chief executive officer of Sonus Networks. "We are focusing our investments on delivering products and services which enhance the value proposition we bring to customers, and we believe the actions we are taking will further strengthen our competitive position for the time when the economic recovery commences and we return to growth mode."

Conference Call Details:

Sonus Networks will host a conference call for analysts and investors to discuss its fourth quarter and full year 2008 results today at 10:00 a.m. ET.

To listen via telephone:

Dial-in number: 800-891-3448
International Callers: +1 212-231-2902

To listen via the Internet:

Sonus will host a live webcast of the conference call.  To access the webcast, visit www.sonusnet.com, Corporate, Investor Relations.

About Sonus Networks

Sonus Networks, Inc. is a market leader in IP communications infrastructure for wireline and wireless service providers. With its comprehensive IP Multimedia Subsystem (IMS) solution, Sonus addresses the full range of carrier applications, including residential and business voice services, wireless voice and multimedia, trunking and tandem switching, carrier interconnection and enhanced services. Sonus' voice infrastructure solutions are deployed in service provider networks worldwide. Founded in 1997, Sonus is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain forward-looking statements regarding future events that involve risks and uncertainties. Readers are cautioned that these forward-looking statements are only predictions and may differ materially from actual future events or results. For a discussion of the risks and uncertainties which could cause actual results to differ from those contained in the forward-looking statements, see "Risk Factors" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2008. Risk factors include among others: the unpredictability of our quarterly financial results; risks and uncertainties associated with the Company's previous restatement of its historical stock option granting practices and accounting including regulatory actions; actions that may be taken by significant shareholders; risks associated with our international expansion; and the impact the current global financial market conditions may have on the telecommunications industry. Any forward-looking statements represent Sonus' views only as of today and should not be relied upon as representing Sonus' views as of any subsequent date. While Sonus may elect to update forward-looking statements at some point, Sonus specifically disclaims any obligation to do so, except as required by law.

Sonus is a registered trademark of Sonus Networks, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.

For more information, please contact:

Sonus Investor Relations:
David Roy / Karin Cellupica
978-614-8615
droy@sonusnet.com
kcellupica@sonusnet.com

Sonus Media Relations:
Lucy Millington
978-614-8240
lmillington@sonusnet.com