Sonus Networks Drives Key Segments of IP Voice Market

Synergy Research Group Reports Sonus Networks Leads North America, Japan, and EMEA Gateway Markets

WESTFORD, Mass., December 17, 2007 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider IP-voice infrastructure solutions, announced today that Synergy Research Group, a leading independent industry analysis firm, has named Sonus Networks the market share leader in key segments of the IP-voice market in its "3Q07 Service Provider Worldwide VoIP Market Share Report." In the high density gateway market, Synergy Research reported Sonus' market leadership position increased on a global basis to 31.4%. The firm also reported Sonus as the market leader, calculated by revenue, in North America, in Japan and, for the first time, in the Europe, Middle East, and Africa (EMEA) region.

"In Q3, Sonus earned a market leadership position in each of its target regions, with particularly strong quarter-over-quarter growth in North America where carriers shifted spending to the back half of the year. In addition, Sonus' recent focus on EMEA has resulted in the company's first quarter of market leadership. That is an important milestone for the Company," said Jeremy Duke, president and CEO, Synergy Research Group.

"Our overall strategy and our ability to execute on a global basis are yielding results. We have successfully anticipated market development patterns and aligned our resources to capitalize on the most promising opportunities worldwide," said Hassan Ahmed, chairman, president and CEO, Sonus Networks. "We continue to make traction with the world's largest and most innovative network operators, to expand into promising new markets, and to grow our deployments with existing customers."

For a copy of the Synergy Research Group Report, entitled "3Q07 Service Provider Worldwide VoIP Market Share Report," please contact Heather M. Wilson, Synergy Research Group, Inc., hwilson@srgresearch.com.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of IP-voice infrastructure solutions 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. Readers are referred to Item 1A "Risk Factors" of Sonus' Quarterly Report on Form 10-Q for the period ended September 30, 2007, filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. Risk factors include among others: the impact of material weaknesses in our disclosure controls and procedures and our internal control over financial reporting on our ability to report our financial results timely and accurately; the unpredictability of our quarterly financial results; risks and uncertainties associated with the Company's restatement of its historical stock option granting practices and accounting including regulatory actions or litigation; risks associated with our international expansion and growth; consolidation in the telecommunications industry; and potential costs resulting from pending securities litigation against the Company. 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.

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.