Sonus Networks Ranked #1 Provider Of VoIP Solutions in Japan For 2005

Industry Report Reaffirms Sonus Market Share Leadership Position

CHELMSFORD, MA, March 22, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice Over IP (VoIP) infrastructure solutions, announced today that an industry report affirmed Sonus' leadership position in the Japanese market for service provider VoIP equipment for Q4 2005, as well as for the entire year 2005. According to a report issued by Synergy Research Group, for the full year 2005, Sonus led the market with a 36.1% market share position, more than double any other equipment provider. Sonus also accounted for approximately 76% of the high density gateway market and more than 61% of the total gateway market in 2005.

Sonus' success in Japan is driven by deployments with many of Japan's largest service providers, which are among the first major operators around the world to initiate large scale replacement of their legacy switching infrastructures and aggressively migrate to all-IP networks. The Company recently announced a multi-million dollar contract with KDDI, the 13th largest service provider in the world, according to Total Telecom's 2005 ranking of the world's 100 biggest telecom network operators (November 2005). The Company has also announced deployments with several of Japan's largest service providers including Fusion Communications, Jupiter Communications (J:COM), NTT, Softbank Broadband and WILLCOM, Inc.

“Japan has been a strategic focus for our Company, as the service providers in that region have been among the earliest and most aggressive to embrace VoIP as the foundation for next generation communications networks,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “Our early position in that critical market, coupled with the proven ability to deploy networks that can scale to meet the needs of the larger players, has propelled Sonus to the number #1 position in Japan.”

“In 2005, the total market for VoIP solutions in Japan continued to grow, and Sonus continued to leverage its early leadership position to increase its foothold in this important country,” said Jeremy Duke, President and CEO of Synergy Research Group. “Sonus' presence in Japan is unmatched by any other equipment provider and the company has succeeded in deploying some of Japan's most advanced IP-based networks.”

“This is a very exciting time in the development of the Japanese VoIP market, which is setting the pace for the migration to all-IP networks around the world,” said Takayuki Oshima, Managing Director, Sonus Networks Japan. “Several of Japan's largest carriers have undertaken large scale replacements of legacy technology with more efficient, scalable, and robust solutions from Sonus Networks.”

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, 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.

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.