New VoIP Network to Drive Network Efficiency and Support Next-Generation Services

CHELMSFORD, Mass., February 06, 2006 - Sonus Networks, Inc. (Nasdaq: SONS), a leading supplier of service provider voice over IP (VoIP) infrastructure solutions, and West Corporation, a premier provider of outsourced communication solutions, announced today that West Interactive Corporation, a wholly owned subsidiary of West Corporation, has selected the Sonus IP Multimedia Subsystems (IMS)-ready architecture as a component of its next generation voice network. West Interactive, which specializes in interactive voice response (IVR) services, is deploying a new VoIP network to cost-effectively increase network capacity and support the development of new revenue-generating services.

The Sonus solution will support incoming voice and data traffic for West Interactive's IVR services using the Sonus GSX9000™ Open Services Switch, PSX™ Call Routing Server, and the Sonus Insight™ Management System. The solution will also enable West Interactive to migrate onto a single IP infrastructure that will allow the company to deliver a host of enhanced services to individual customers and enterprises.

West Corporation currently provides contact services to many of the Nation's Fortune 1000 companies. Sonus' standards-based solution will provide West Corporation with the infrastructure necessary to cost-effectively deliver a full suite of IVR services, such as automated customer acquisition and support applications, while enabling the company to rapidly deliver feature rich services to its enterprise customers.

“West Interactive requires a truly carrier-grade solution in order to effectively deliver sophisticated services to their Fortune 1000 customers. By building a new VoIP network based on Sonus, West Interactive will be able to deliver superior services while streamlining their operating efficiencies,” said Bert Notini, president and COO, Sonus Networks. “We're pleased that West has selected Sonus for the initial rollout of their IP-based voice network, and we look forward to working with them in the future as they continue to scale their network and introduce enhanced services.”

“Our clients depend on reliable communications services. As a result, we require a network that offers carrier-class call quality and network reliability,” said Craig Webster, senior vice president of systems development, West Interactive Corporation. “We evaluated a number of technology solutions, but Sonus' solutions and their track record for delivering top of the line technology made Sonus the clear choice.”

“West Interactive's investment in Sonus offers strategic advantages on several levels,” said Brian Partridge, Senior Analyst with Yankee Group. “With more and more companies looking to capture a consumer's attention, businesses need to be savvy about the way they connect with their customers. IP-based technologies provide a solid foundation not only for the more efficient management of existing services, but also for a viable platform for the rapid introduction of new services that will help companies improve communications.”

Sonus' IMS-based architecture has been deployed by some of the world's most innovative network operators worldwide, and offers both enterprise and service provider customers with the ability to rapidly develop revenue-generating enhanced services. The GSX provides critical voice over packet capabilities and serves as the transitional element between legacy and packet networks, while the Sonus PSX is designed to support the routing and delivery of a full-suite of IP-based services required for a complete enterprise or consumer IP-based network. Sonus Insight is a web-based management system designed to simplify the operation of packet voice networks. Sonus' Element Management System, a component of Sonus Insight, offers a streamlined approach to network management and performance monitoring by offering network operators a comprehensive view of the network and back office systems. In an enterprise environment, Sonus Insight enables communication service providers to quickly respond to changing customer needs.

The solution will be deployed and supported by Sonus Services, a worldwide organization responsible for network design, systems integration and life cycle management.

About West Corporation

West Corporation is a leading provider of outsourced communication solutions to many of the world's largest companies. The company helps its clients communicate effectively, maximize the value of their customer relationships and drive greater revenue from each transaction. West's integrated suite of customized solutions includes customer acquisition, customer care and retention services, interactive voice response services, and conferencing and accounts receivable management services. Founded in 1986 and headquartered in Omaha, Nebraska, West has a team of approximately 27,000 employees based in North America, Europe and Asia. For more information, please visit www.west.com.

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 15, 2005, and the “Cautionary Statements” section of Sonus' Quarterly Report on Form 10-Q, dated November 8, 2005, 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.

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