Managed Voice over Broadband Service Leverages Sonus' Industry Leading IMS-Ready Architecture

CHELMSFORD, Mass., September 13, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider Voice over IP (VoIP) infrastructure solutions, and Whaleback Systems, a managed services provider and a leader in IP PBX innovations, announced today Whaleback Systems is leveraging Sonus' industry-leady IP Multimedia Subsystem (IMS)-ready architecture to support the Whaleback CrystalBlue Voice Service". By deploying the Sonus-based network, Whaleback Systems is providing small and medium size businesses (SMBs) with state-of-the-art, feature-rich Voice over Broadband service, with the superior quality and reliability that businesses rely on to increase productivity and support their communications needs.

Improved communication has a material impact on business users, whether in large enterprises or SMBs, but SMBs typically don't have the resources to manage a complex telecom network, said Mark Galvin, president and CEO of Whaleback Systems. Our managed PBX approach takes away the complexity while leveraging the cost efficiencies of voice over broadband. By building our service on a Sonus-based infrastructure, our customers never have to sacrifice quality or reliability.

Whaleback Systems is deploying a suite of Sonus' solutions, including the GSX9000" Open Services Switch, PSX" Call Routing Server, SGX" Signaling Gateway, and the Sonus Insight" Management System.

Whaleback Systems' targeted approach to the market, focusing specifically on SMB users, means that they place an even higher premium on cost efficiency coupled with superior service, said Steve Edwards, chief marketing officer, Sonus Networks. By selecting Sonus as the foundation for its voice over broadband network, Whaleback is able to offer its customers access to a carrier-quality network with robust calling features, such as 'follow-me' calling, desktop messaging, and video calling.

The CrystalBlue Voice Service is a premises-based, software-driven solution ideal for companies that require 5-500 phone stations. The managed service is deployed with a dedicated, "voice-only" broadband connection to the DSL or cable infrastructure to ensure that voice services receive required quality of service levels.

About Whaleback Systems

Whaleback Systems is a Managed Service Provider (MSP) and the pioneering developer of the first business phone solution built from the ground up for broadband. Unlike traditional systems, the Whaleback CrystalBlue Voice Service is 100 percent premises-based and software-driven. It includes the only IP PBX with Key System Unit features and Road Warrior Functionality. Whaleback's all-inclusive, unlimited nationwide calling package makes the most advanced technology immediately affordable for companies that need between 5 and 500 phone stations. The Whaleback service is available through partnerships with channel partners and VARs. For more information, visit www.WhalebackSystems.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' 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.