The Carphone Warehouse Connects Over One Million UK Mobile Phone Users on Its Sonus Based Next Generation Network

Sonus Expected to Carry 3.5 million UK Broadband Users by 2010

WESTFORD, Mass., March 17, 2008 – Sonus Networks (Nasdaq: SONS), the market leader in IP-voice infrastructure, and The Carphone Warehouse Networks, a subsidiary of the Carphone Warehouse Group have announced that over one million phone users in the UK are now live on its next generation network infrastructure which is supported by the Sonus IP-based platform. The Carphone Warehouse Networks made the decision to invest in its own next generation network in 2005, principally to support its TalkTalk free broadband offer. The Carphone Warehouse Networks' complete IP-based voice network allows the Company to support accelerating demand for its communications services. Sonus technology is supporting the dramatic expansion in The Carphone Warehouse Networks residential voice business, and the major milestone of more than one million subscribers was achieved in just 27 months. The Carphone Warehouse Networks estimate that by 2010 it will have 3.5 million broadband subscribers for this service.

"The sophistication of our current communications infrastructure allows us to deliver the quality of service that our customers demand," said Neil McArthur, Managing Director, The Carphone Warehouse Networks. "By utilizing the Sonus platform, we have created a large, stable network that delivers the high quality voice experience consumers demand and also positions us to support rapid subscriber growth. As a result, we have quickly reached the one million mark, a significant milestone for the Company."

Carphone Warehouse Networks' success with its TalkTalk Broadband services demonstrates the scalability and reliability of next generation technology from Sonus Networks. The Sonus platform enables service providers to rapidly replace legacy networks with a more efficient, scalable and IP-based solution. Unlike the traditional legacy players that require localised points of presence across the UK, The Carphone Warehouse Networks is able to host network switches in just three locations to reach over 70% of UK households with scope for further expansion in the future. This helps to reduce dramatically the total cost of the business and keep tariffs low.

"By deploying a next generation network infrastructure, The Carphone Warehouse Networks has successfully become one of the UK's most innovative network operators," said Hassan Ahmed, chairman and CEO, Sonus Networks. "Sonus will continue to partner with Carphone Warehouse to enable it to deliver new differentiating services, respond to growing customer demands and take advantage of market conditions. It has the infrastructure to continue to create a distinct competitive advantage and rapidly grow its subscriber base."

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.

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

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-K for the period ended December 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, except as required by law.

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.