With a Presence in Major Networks, Sonus is the Market Share Leader in Japan

CHELMSFORD, Mass., October 3, 2005 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, announced today that the Company holds a dominant leadership position in the Japanese market for service provider VoIP equipment, according to a report recently issued by Synergy Research Group. In the second quarter of 2005, Sonus accounted for more than 65% of the high density gateway market and more than 54% of the total gateway market, reaffirming Sonus' preeminent position in one of the world's most aggressive Voice over Broadband markets. To date, Sonus has announced deployments within some of Japan's largest networks, including Fusion Communications, Jupiter Communications (J:COM), NTT, and Softbank Broadband.

“Japan has been a leading player in the adoption of Voice over Broadband solutions, and Sonus has clearly established itself as a trusted provider of carrier grade solutions in that dynamic market,” said Jeremy Duke, president and CEO, Synergy Research Group. “Sonus not only holds the number one market share position, but also they have outpaced their nearest competitor by more than 3x.”

Japan, which has been a key driver in global Voice over Broadband adoption, has been a strategic focus for Sonus. According to a broadbandtrends.com report entitled “Market Momentum Drives Broadband Telephony,” at the end of 2004, Japan accounted for 67% of the world's VoBB subscribers.

“Japanese network operators have eagerly embraced the power of Voice over Broadband to offer consumers competitively priced, highly robust voice offerings,” Teresa Mastrangelo, principal analyst, broadbandtrends.com. “As Japan drives towards nationwide deployment, Sonus' firmly established incumbency in some of Japan's largest networks puts the company in a favorable position to capitalize on the continued migration to VoBB solutions.”

“Many service providers in Japan were early adopters of Sonus' technology. Our success in the region is a testament to the reliability and carrier-grade performance of our solutions,” said Hassan Ahmed, chairman and CEO of Sonus Networks. “Japan continues to be a catalyst in the world's VoBB market, and we are committed to working with our Japanese partners to drive the adoption of innovative new VoBB services.”

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 of U.S. 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 15, 2005, and the “Cautionary Statements” section of Sonus' Quarterly Report on Form 10-Q, dated August 8, 2005, 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.

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.