WESTFORD, Mass., November 8, 2007 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider IP-voice infrastructure solutions, today announced that BT Group, one of the world's leading providers of communications solutions and services, has selected Sonus as an official 21CN vendor to supply an Access Gateway Control Function (AGCF) capability to support BT's 21st Century Network programme (21CN). The Sonus solution will enable communications providers to interconnect with BT's 21CN and leverage its next-generation capabilities to provide converged multimedia services to end user customers. 

"21CN is BT's next generation network, an advanced communications network for the future. 21CN is designed to empower the end-user with control, choice and flexibility like never before and offer communications services from anywhere to any device. This ambitious and exciting programme will enable a new generation of rich personalized services, transforming people's personal and business lives," said George Nazi, Managing Director, 21CN Core Convergence, BT Group. "For us, the move to IP is about more than technology, it is about changing the way people communicate. We've selected Sonus Networks for AGCF based on its proven ability to consolidate complex networks and systems."

Sonus has been selected as the preferred vendor to supply the AGCF component of the 21CN implementation. BT will deploy the Sonus' ASX™ Access Server to control the network's multi-service access nodes (MSANs), devices that are installed in telephone exchanges to connect end-users' telephone lines with the core next-generation network (NGN).

"BT's 21CN is at the forefront of the world's most innovative technology. BT is truly a customer-driven operator and is executing on a plan to transform the UK into the most advanced telecommunications nation, making a meaningful difference in people's lives," said Hassan Ahmed, president, chairman and CEO, Sonus Networks. "Sonus is a leading next-generation communications supplier that has deployed solutions that meet the complex AGCF requirements for UK residential and enterprise services. Working with BT and with support from the other 21CN suppliers, we're planning to mirror our success with other operators around the world and meet BT's aggressive deployment goals. I firmly believe that information and communication technology can play a dramatic role in people's lives, and we are proud to be working with BT to transform the communications landscape in the UK."

BT Group plans to deploy the complete Sonus access solution, including the ASX™ Access Server, a key component of Sonus' IP Multimedia Subsystem (IMS) architecture, as part of its AGCF project plan. The Sonus platform is currently deployed in more than 150 networks worldwide, and according to iLocus Research, carries more than 35 billion minutes of IP voice traffic each month, 3.5 times the amount of any other IP-voice provider.

About BT Group

BT is one of the world's leading providers of communications solutions and services operating in 170 countries. Its principal activities include networked IT services; local, national and international telecommunications services; higher-value broadband and internet products and services and converged fixed/mobile products and services. BT consists principally of four lines of business: BT Global Services, Openreach, BT Retail and BT Wholesale.

In the year ended 31 March 2007, BT Group plc's revenue was £20,223 million with profit before taxation of £2,484 million.

British Telecommunications plc (BT) is a wholly-owned subsidiary of BT Group and encompasses virtually all businesses and assets of the BT Group. BT Group plc is listed on stock exchanges in London and New York. 

For more information, visit www.bt.com/aboutbt

About Sonus Networks

Sonus Networks, Inc. is a leading provider of IP-voice 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 Westford, 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 Item 1A "Risk Factors" of Sonus' Quarterly Report on Form 10-Q for the period ended June 30, 2007, filed with the SEC, 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 restatement of its historical stock option granting practices and accounting including regulatory actions or litigation; 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.