Synergy Research Group Names Sonus a Leader in IP-Based Voice Solutions in Q1 2006

CHELMSFORD, Mass., May 31, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, announced today that Synergy Research Group, a leading independent industry analysis firm, has named Sonus Networks the market share leader in high density media gateways, a key component in Sonus' award winning IP Multimedia Subsystem (IMS)-ready architecture. With 30% of the market in Q1 2006, Sonus is leading the world's migration to IP-based voice with carrier-class solutions that offer service providers greater operating efficiency and end users access to a broad range of new communications services.

“Sonus is focused on driving the penetration of IMS-ready solutions in markets around the world. Our customers are some of the most recognized brands in the communications industry, and they rely on us every day to deliver robust solutions and exceptional service,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “We're proud to be the number one market share leader in this important category as it underscores our ability to execute on our strategic vision for transforming the world's communication networks.”

“Sonus' strong performance in Q1 is reflective of the key role the company has played in helping service providers migrate their networks to VoIP,” said Jeremy Duke, president and CEO, Synergy Research Group. “From the Company's inception, Sonus has been solely focused on delivering some of the industry's most sophisticated IP-based voice technologies, and their market leadership this quarter is reflective of the strength of their solutions and the success of their go-to-market strategy.”

For a copy of the Synergy Research Group Report, entitled “1Q06 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 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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