Acquisition Extends Company's Growing IP Services and Solutions with New Provisioning Services

Westford, MA., April 21, 2008 – Sonus Networks (Nasdaq: SONS), a market leader in IP communications infrastructure, today announced it has completed the acquisition of Atreus Systems, a supplier of IP voice and advanced IP service provisioning software. Atreus' expertise in the integration of operating support systems (OSS) and the provisioning of IP services for fixed-line and mobile operators' access networks fosters the evolution of IP architectures globally. The combination of Atreus' services and solutions with Sonus' leadership in IP infrastructure will enable carriers and network operators around the globe to rapidly deploy innovative communication services to their subscribers.

This acquisition demonstrates Sonus Networks' commitment to being a trusted partner for the world's largest carriers. With the Atreus solutions as part of the established Sonus Access portfolio, Sonus is able to provide comprehensive integration services for operators' growing IP-service portfolios, with the network management systems, billing and customer care systems providing a seamless consumer experience for the carrier subscriber.

"The combination of Sonus Networks and Atreus Systems provides the next step in creating a simple and integrated IP communications environment to manage next-generation communications services for consumers around the globe," said Hassan Ahmed, CEO at Sonus Networks. "The key to advancing complete IP networks for voice, data and multimedia services is to provide solutions that increase functionality and ease of use, allowing dependable and innovative environments that make IP services a reality.  Our five-year relationship with Atreus convinced us that its technology will help accelerate the industry's growth and complement our access solution portfolio."

The IP provisioning software developed by Atreus Systems has been deployed with some of North America's largest carriers. The Atreus IP Service Provisioning Solution delivers pre-integrated, automated provisioning and configuration for a variety of devices, helping providers to deploy offerings quickly so that they can generate new revenue. Now as part of the Sonus Networks offering, operators will be able to leverage the dedicated expertise of the global Sonus team. Sonus has a heritage and deep understanding of IP infrastructure, applications and operators' operating systems, which are required to increase the speed of service delivery. Today, Sonus Networks' IP migration solutions offer one the most effective ways of getting new monetized services out to customers.

"Atreus Systems has built an award winning IP Service Provisioning Solution that helps providers deploy offerings quickly so that they can generate new revenue. The OSS in many of these large carriers is complex, so integration with their infrastructure is a key to the success of these deployments," said Andrea Baptiste, CEO at Atreus Systems. "With Atreus' joining Sonus Networks, customers will have access to the highest levels of IP integration expertise, and our technology will be available through a global organization to meet the growing demand for IP migrations and the necessary back office integration to deliver the mulitplay services required by business and home subscribers alike."

Founded in 1999, Atreus Systems is headquartered in Ottawa, Canada. Atreus' provisioning platform is based on a robust and flexible industry-standard J2EE architecture that enables providers to provision new residential voice subscribers simply and rapidly using process automation, device- and vendor-specific adaptors, and wizard-driven self-service portals.

The financial terms of the agreement were not disclosed.

About Sonus Networks

Sonus Networks, Inc. is a market leader in IP communications infrastructure 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' Annual 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.

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