Nation's Largest Wireless Provider Leverages Sonus-Based Architecture to Deliver Premium Quality Voice Service

CHELMSFORD, Mass., August 7, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) network infrastructure solutions, today announced that Cingular Wireless, the nation's largest wireless provider, is expanding its Sonus-based, next generation voice network.

“We're proud to play such a critical role in the growth and support of one of the largest IP-based wireless voice networks in the world,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “Sonus solutions allow wireless network operators to seamlessly grow their networks, support the rapid delivery of new services, and provide the quality of service that is a prerequisite for any carrier-grade solution.”

Cingular Wireless has deployed a full suite of Sonus' next generation SMARRT Wireless voice solutions, establishing an extensive nation-wide long-distance IP-based voice network and has established gateway mobile switching centers (Gateway MSCs) across the United States. The Sonus-based network has been carrying live customer traffic since 2003. In this next phase of the network deployment, Cingular is expanding its Sonus-based national service network to support increased traffic volumes. The expansion will also combine the existing Gateway MSC deployments, giving Cingular one of the largest carrier grade IP-based wireless voice networks in the world. Cingular's new enhanced network architecture will enable the rapid addition of new subscribers and the delivery of new 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. 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' Quarterly Report on Form 10-Q, dated May 8, 2006, filed with the Securities and Exchange Commission, 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 announced review of its historical stock option grants and accounting, including any potential impact of the Company's financial statements or results, the Company's inability to timely report with the Securities and Exchange Commission, the Company's potential inability to meet NASDAQ requirements for continued listing, potential investigations or litigation arising out of the review or any restatement; 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. All other company and product names may be trademarks of the respective companies with which they are associated.