Carphone Warehouse Transforms Telephony with the World's Most Advanced Residential and Enterprise IP-Voice Network

WESTFORD, Mass., September 26, 2007 – Sonus Networks (Nasdaq: SONS), a leading supplier of IP-voice infrastructure solutions, and Carphone Warehouse Networks, a subsidiary of the Carphone Warehouse Group, celebrated the one-year anniversary of the Group's free TalkTalk Broadband service built on its Next Generation Network using the Sonus platform. In under a year, the network division is on track to connect more than 2.6 million subscribers onto one of the most vibrant, cost-effective communications services in the world. Carphone Warehouse Networks is the only national provider in the UK to offer a Next Generation Network (NGN) based telephony service plus broadband data services.

"Carphone Warehouse Networks is committed to advancing its position as one of the UK's most innovative network operators. Carphone Warehouse Networks is taking aggressive steps to utilize its sophisticated communications infrastructure to extend the benefits of IP communications across the country," said Neil McArthur, Managing Director, Carphone Warehouse Networks. "Sonus' platform has been a critical element in the success of our drive to deliver advanced communications services to residential and business markets in the UK, and it is what differentiates our service and ability to reach the market."

The Carphone Warehouse Networks portfolio of IP-based services integrates advanced telephony services and 8 Mbps high-speed Internet broadband access. The industry-leading IP services are delivered over its core fiber network. Carphone Warehouse Networks is continuing to expand its already fiber-rich network, bringing IP-Voice services even closer to residential homes and businesses using the most advanced technologies and Sonus' robust voice platform. The NGN currently supports in excess of 600,000 subscribers and expects to reach nearly one million households as part of its initial deployment by the end of its 2007/08 financial year. In addition to providing residential voice service, the network also serves as the backbone for the business to business division, Opal Telecom.

Sonus Networks was able to develop, integrate and deploy the initial phase of the next-generation voice solution within five months of being selected for the deployment, enabling Carphone Warehouse Networks to launch service quickly into the market. In addition to selecting Sonus' industry-leading voice platform, Carphone Warehouse Networks also selected Sonus' advanced network monitoring and integration solutions. With the Sonus Insight(TM) Management System and SonusCARE portfolio of professional services, Carphone Warehouse Networks has the ability to monitor in real-time the back-office integration and network inter-working. Further, Carphone Warehouse Network' operations staff is continuing to leverage Sonus' support and training to optimize the network.

"Carphone Warehouse Networks is a prime example of what can be achieved when operators harness the power of IP communications to reshape their networks," said Hassan Ahmed, chairman and CEO, Sonus Networks. "Carphone Warehouse Networks is a true innovator that made the right technology decisions to enable them to capitalize on a favorable regulatory environment and launch a communications service that consumers find compelling. We're proud to celebrate the success of their one-year anniversary, and look forward to the continued success of our partnership."

In September 2005 the UK's Office of Communications (OFCOM) passed a regulatory decision requiring the unbundling of the last mile infrastructure to the home, known as Local Loop Unbundling. Carphone Warehouse Networks selected Sonus to seize this new opportunity and offer the British telecoms market an aggressive package of incumbent-equivalent voice services and high-speed broadband. Five vendors competed for the project. Sonus was selected because of its proven expertise in building IP networks and unique ability to deliver a robust, scalable IP-based network that supported incumbent-equivalent residential and enterprise features. In mid-2006, OFCOM also conducted an auction to determine which wireless carriers will be allowed to provide services using the 3.3MHz spectrum at the top end of the GSM 1800 MHz band, and Carphone Warehouse was successful in purchasing one of those licenses.

Carphone Warehouse Networks has deployed the complete, end-to-end Sonus solution, including the ASX(TM) Access Server, GSX9000(TM), PSX(TM) Call Routing Server, SGX(TM) Signaling Gateway, and the Sonus Insight Management System to deliver a unique primary line residential voice service.

The Carphone Warehouse Networks network deployment highlights the significant benefits that next generation technology offers, enabling service providers to rapidly replace legacy networks with a complete IP-based solution that can scale to support millions of users with compelling services. In addition to the service benefits for end users, the Sonus platform also enables significant operational cost optimization. Unlike the traditional legacy players that require localized points of presence across the UK, Carphone Warehouse Networks is able to host network switches in just three locations to reach approximately 80% of all UK residents, dramatically reducing the cost of ownership.

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 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 March 31, 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.

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