Opal Telecom Deploys Sonus Solutions to Support Carphone Warehouse's 21st Century Voice Service, TalkTalk;
Innovative New Service is One of Europe's Fastest Growing IP-Based Voice Offerings

SWINDON, UK, June 27, 2006 – Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, and Opal Telecom, a subsidiary of Carphone Warehouse, one of the United Kingdom's largest telecommunications network operators, announced today that as part of a multi-million dollar contract with Sonus, Opal Telecom has deployed Sonus solutions as the foundation for Carphone Warehouse's next-generation network. By leveraging Sonus' IP Multimedia Subsystem (IMS)-ready architecture, which includes the full set of UK primary line residential call features, Carphone Warehouse will be able to leverage Opal's Sonus-based network to deliver a unique value proposition to residential customers throughout the UK. In addition, by deploying Sonus' industry-leading infrastructure, Carphone Warehouse is positioned to be a leading next generation telecommunications provider.

“Carphone Warehouse is one of the most recognized brands in the European telecommunications industry, and we are proud that Opal Telecom has selected Sonus as its strategic supplier for its next-generation voice network,” said Hassan Ahmed, chairman and CEO, Sonus Networks. “Recent regulatory changes are transforming the competitive landscape, and Opal Telecom is one of the first service providers to fully embrace the opportunity. The Sonus solution allows Carphone Warehouse to deliver a high quality residential service with today's UK call features, but more importantly, the solution provides the foundation for future multi-media and wireless services.”

Designed to reach nearly 70% of the population in the UK, Opal's next generation network will be one of the most sophisticated telecommunications networks in the world. Opal will deploy 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 that enables enhanced capabilities while supporting the stringent demands for reliability and telecom-grade quality of service. The Sonus/Opal network deployment highlights the significant benefits that next generation technology offers, enabling service providers to rapidly replace legacy networks with a full scale IP-based solution that can scale to support millions of users.

“Sonus is the premier provider of next-generation telecommunications solutions worldwide. Our investment in a Sonus-based network will allow us to offer our customers an enhanced voice service with the same or better service quality than our customers receive today,” said Neil McArthur, managing director, Networks, Opal Telecom. “Consumers and businesses throughout the UK will now have an unprecedented opportunity to enjoy a truly converged voice service, using their existing telephone equipment. The Opal network currently carries over 1.5 billion minutes of voice traffic per month, and by the end of 2006, we hope to have doubled that number. We are confident that by selecting Sonus as the foundation for our next-generation network, we are deploying the platform that will enable us to successfully support our customers now and into the future.”

Opal's nationwide deployment is driven by the recent regulatory decision from the UK's Office of Communications (OFCOM) requiring the unbundling of last mile infrastructure to the home, which is known as Local Loop Unbundling (LLU). In February 2006, the Office of the Telecommunications Adjudicator (OTA) announced that, according to the new consolidated forecast, an estimated 2-3 million lines will be unbundled by the end of 2006.

“The telecommunications environment in the United Kingdom is currently undergoing a massive overhaul, creating a significant opportunity for new players like Carphone Warehouse to challenge British Telecom's market position,” said Teresa Mastrangelo, principal analyst with Broadbandtrends.com. “Selecting Sonus as the foundation for its network will help Carphone Warehouse capitalize on this tremendous opportunity by deploying a highly scalable carrier class network quickly and efficiently.”

“Sonus is committed to extending its global leadership position by becoming the number one preferred provider of carrier grade voice solutions in Europe,” said Joop van Aard, vice president, Europe, Middle East & Africa, Sonus Networks. “Sonus established an early foothold in the emerging European market, and Opal's decision to deploy our technology as the foundation of its network reaffirms Sonus' position as an industry leader. We're extremely proud to be working with one of the region's premier communications providers.”

Carphone Warehouse's TalkTalk phone service is one of the region's fastest growing voice services, and since launching the service in 2003, more than 2.6 million people have signed up. In April 2006, TalkTalk launched the UK's first ever FREE broadband service and already has over 340,000 subscribers. Given Opal's nationwide footprint, Carphone Warehouse's new voice service has the potential to reach nearly 70% of UK residents making it the largest Sonus-based, residential voice network in the world.

Sonus, Opal and Gartner will be hosting a webinar with the financial community at 12:30 pm ET (5:30 pm BST) today, June 27th, to further discuss this announcement. To view a webcast of this event and other financial conferences, or to obtain a schedule of upcoming events, please visit the Sonus Networks Investor Relations site at:

To join the conference via telephone:
Dial-in number: 800-313-6989
International Callers: 212-231-6047

Replay

A telephone playback of the call will be available following the conference and can be accessed by calling (800) 633-8284, or for international callers, please call +1 (402) 977-9140. The reservation number for the replay is 21297530. The telephone playback will be available through July 11, 2006.

A replay of the webcast will be also available on the Sonus Networks Investor Relations site through Wednesday, June 27, 2007. To access the replay of the webcast, visit www.sonusnet.com, Corporate, Investor Relations.

About Opal Telecom

Opal is one of the UK's largest telecom network operators and is a wholly owned subsidiary of The Carphone Warehouse plc (a FTSE 250 company). With headquarters in Warrington and divisions in Manchester, London, West Midlands, Leeds, Glasgow and Belfast, the company offers voice services primarily to the Corporate and SME (small and medium sized enterprises) market in the UK.

Opal combines technological innovation, customer service excellence, service quality and competitive pricing with a range of unique value-added services such as call recording, screening and queuing to ensure their customers remain competitive, creative and efficient.

Opal employs over 700 staff and currently manages over 150,000 business customers. Opal has grown substantially and turnover to March 2005 was £285m.

Opal is the network operator for Carphone Warehouse's residential TalkTalk 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 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' Annual Report on Form 10-K, dated March 14, 2006 and Quarterly Report on Form 10-Q, dated May 8, 2006, both filed with the SEC, which identify 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 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.