Completion of OSMINE Signifies Interoperability with RBOC Networks

WESTFORD, Mass., January 7, 2002 – Sonus Networks (Nasdaq: SONS) today announced that it has successfully completed the Telcordia Technologies, Inc. OSMINE Services process for its industry-leading packet voice infrastructure solutions. Sonus has completed its final phase of the OSMINE process, allowing it to offer full capacity and provisioning integration for Sonus solutions within a Regional Bell Operating Company (RBOC) environment.

Sonus' OSMINE initiative enables RBOCs to provision, monitor and manage Sonus' packet voice solutions, including the GSX9000(TM) Open Services Switch and PSX Policy Server and SGX SS7 Gateway modules of the Insignus(TM) Softswitch, in a seamless fashion. Sonus has completed the Telcordia(TM) TIRKS System for the GSX9000, and the Telcordia(TM) Network Performance Monitor System and Telcordia(TM) Network Capacity Manager System for the GSX9000 and PSX and SGX softswitch modules. Sonus expects to complete the Telcordia NMA System for the GSX9000 by the end of January.

"The interoperability between OSS and network elements is key in helping to manage the complexities of provisioning, engineering and quality of service in next generation networks," said Dennis Tinley, vice president, Customer Solutions, Telcordia. "The software solutions provided by Telcordia are proven and field tested with the world's premier service providers. We are pleased to work with Sonus, who clearly recognizes the value of OSS to their customers."

Equipment manufacturers that offer network elements and operations systems to the RBOCs must be certain that these products interoperate with the RBOCs' large embedded base of operations systems. To facilitate this interoperability, Telcordia Technologies established the OSMINE Services process. This process integrates equipment manufacturers' products with Telcordia-developed operations systems, and encourages systems integration in a multi-vendor environment.

"The OSMINE process is critical to the proliferation of next-generation packet voice infrastructure among incumbent local exchange carriers," said Mike Hluchyj, founder and chief technology officer, Sonus Networks. "RBOCs can be confident that they can deploy Sonus solutions for applications such as interoffice tandem switching, business PBX access and Internet call diversion today, and our equipment will easily and transparently integrate with the carriers' existing back-office systems."

"Over the years, BellSouth has made significant investments in its back-office systems, from both a cost perspective and from a resources perspective," said Steve Turner, director of Network Transformation, BellSouth Corporation. "While BellSouth is focused on transforming its network to a next-generation infrastructure, it also wants to leverage these past investments in operational systems. By gaining OSMINE compliance, Sonus assures that its solutions will be easily assimilated with BellSouth's provisioning, billing and management processes, allowing for seamless network deployment."

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture(TM) (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus' award-winning voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, is headquartered in Westford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus 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 Sonus' Quarterly Report on Form 10-Q, dated November 14, 2001, filed with the SEC, which identifies important risk factors that could cause actual results to differ from those contained in the forward-looking statements. These risk factors include, among others, the Company's ability to grow its customer base, dependence on new product offerings, market acceptance of its products, integration risks relative to its acquisition of telecom technologies, rapid technological and market change and manufacturing and sourcing risks.

GSX9000, Insignus and Open Services Architecture are trademarks of Sonus Networks. Open Services Partner Alliance is a service mark of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.