Independent Research Firm, Infonetics, Reports Sonus Market Share Leader in Several Categories of IP Multimedia Subsystem (IMS) Solutions

CHELMSFORD, Mass., May 24, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today Infonetics Research, a leading independent industry research firm, has named Sonus Networks the market share leader in several segments of the VoIP market for Q1 2006 in its “Service Provider Next Generation Voice and IMS Equipment Market Forecast.”

“The results of the Infonetics report are reflective of Sonus' strong start to 2006. In Q1 alone, we announced 8 new customer projects, expanded our presence in the European market, continued to innovate and develop our product line, and solidified our position as a market leader of IP-based voice solutions,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “Sonus is a trusted provider to many of the world's largest communications service providers, and our unwavering commitment to their success has helped us earn a #1 market share position in this exciting industry.”

The Infonetics report named Sonus the market leader in several categories including the worldwide trunk media gateway segment with 16% of the total market and the high density gateway market with 22% of the total market. Sonus' award winning IP Multimedia Subsystem (IMS)-ready solutions form the foundation of today's leading IP-based voice networks, and currently support over 19 billion minutes of voice traffic per month.

“Sonus has historically been a very strong leader in the VoIP market, and in Q1, their focus on expanding their deployments with existing customers and driving into new markets resulted in a very impressive start to 2006," said Stéphane Téral, Directing Analyst, Service Provider Next Gen Voice and Mobile Core, with Infonetics Research. "Sonus' distributed IMS-ready architecture has been one of the company's key strengths as service providers migrate from PSTN to IP infrastructures.”

For a copy of the Infonetics Research report, please contact Larry Howard at 408.583.3335 or larry@infonetics.com.

About Sonus Networks

Sonus Networks, Inc. is a leading provider of Voice over IP (VoIP) 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 Chelmsford, 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 the “Risk Factors” section of Sonus' Annual Report on Form 10-K, dated March 14, 2006 and Quarterly Report on Form 10-Q, dated May 8, 2006, both filed with the SEC, which identify 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 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.

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