Sonus Networks and NeuStar Partner to Empower Consumers with Presence-Enabled IMS Applications

Industry Pioneers Team to Provide Consumers with Greater Control and Flexibility over Communication Experience

WESTFORD, Mass. and CHICAGO, IL, June 20, 2007 – Sonus Networks, Inc. (Nasdaq: SONS), a leading provider of Voice over IP (VoIP) infrastructure solutions, and NeuStar, Inc. (NYSE: NSR) today announced their partnership to create feature-rich IP Multimedia Subsystem (IMS)-based consumer applications with presence technology. This new integration effort is an expansion of Sonus' existing relationship with NeuStar, and builds on Sonus' role as a SIP-IX Alliance partner.

The Sonus IMX^™ Multimedia Application Platform, a key element in the application layer of Sonus IMS-based network architecture, has been successfully integrated with NeuStar's Presence Platform (PSP). Part of NeuStar's suite of next generation messaging services, the PSP incorporates a presence server and group list management server (GLMS), which power presence-enabled IMS-based applications. This partnership means that network operators can quickly deploy superior quality voice and customized presence-enabled IMS services for end users.

IMS is designed to create seamless communications regardless of network, enabling advanced interactive services such as VoIP and multimedia. Presence information enriches communications by providing real-time information about a user's availability; it provides visibility on how best to communicate and is the enabler for advanced next generation services.

"End users want to enjoy a personalized, advanced communications experience. Our customers are creating advanced messaging and presence-enabled services to meet these needs using NeuStar's pioneering next generation messaging services, integrated today within 27 operator networks worldwide," said Allen Scott, general manager of NeuStar Next Generation Messaging (NGM). "We work with industry leaders and welcome Sonus into our partner program, providing operators with market-leading next generation services."

"Many of today's most popular Internet applications feature presence, instant messaging, and the ability to dynamically manage the administration of services, and the telecom world is starting to catch up," said John Nye, Vice President, Applications Solutions, Sonus Networks. "By partnering with an industry leader like NeuStar, Sonus is able to combine its vast expertise building the world's most robust IP-voice networks with the features and services most in-demand by today's consumers. In addition, because the applications are supported by the Sonus platform, network operators can be confident in the quality, reliability and the scalability of their customer-facing solutions."

About NeuStar NGM

NeuStar, Inc. (NYSE: NSR) is a leading provider of essential clearinghouse and directory services to the global communications and Internet industry. In November 2006, NeuStar created its Next Generation Messaging (NGM) Services by acquiring Followap Inc., a leading global provider of instant messaging, presence, and interconnect services.

Powering leading IMS networks such as Nortel and working in close partnership with handset manufacturers and Internet Service Providers (ISPs), NeuStar's NGM Services enable subscribers to stay connected through real-time, presence-enabled next generation services. Today, 26 leading mobile operators including Vodafone Group, Turkcell, Hutchison 3, Wind, SFR, Swisscom and Mobinil are NeuStar customers, and have a combined user base of close to 300 million subscribers. For more information about NGM please visit www.neustar.biz/ngm

NeuStar, Inc. is headquartered in the United States, with subsidiary offices in Europe and Asia. For more information, please visit www.neustar.biz

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 dated May 8, 2006, 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 announced review of its historical stock option grants and accounting, including any potential impact on the Company's financial statements or results, any tax liabilities or penalties, the Company's inability to timely report with the Securities and Exchange Commission, whether the Nasdaq Listing Council will continue the delisting stay or grant an extension or that the company's securities will remain listed on the NASDAQ Stock Market, potential investigations, regulatory actions or litigation arising out of the review or any restatement; 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, Inc. All other company and product names may be trademarks of the respective companies with which they are associated.