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Sonus Platform Supports Residential and Enterprise Voice over Broadband Offerings

CHICAGO, Ill., June 23, 2004 – Sonus Networks (Nasdaq: SONSE), a leading provider of voice over IP (VoIP) infrastructure solutions, today announced that it is delivering solutions to facilitate the deployment by major service providers of voice over broadband (VoBB) services to consumers and enterprises. In a related announcement, Qwest today announced that it is implementing Sonus’ solutions as the foundation of its Qwest OneFlex service (see Qwest’s press release “Qwest Communications Launches Industry-Leading Voice over IP Service for Business Customers”).

“There is no denying that the world is moving to a broadband voice infrastructure,” said Michael O’Hara, vice president, marketing, Sonus Networks. “This is not a migratory strategy for service providers – broadband is truly a disruptive technology that is reshaping the competitive dynamics of the telecommunications market. For carriers, it enables them to expand their service offerings without owning the last mile and to offer bundled voice, data and multimedia services. For consumers, it provides cost-effective, innovative voice services over their broadband connections, using their existing telephones.”

Sonus’ VoBB solution delivers basic local area calling features as well as advanced IP-based functionality over broadband technologies including DSL and cable, providing a lower-cost and flexible alternative for residential and enterprise telephone services. Features and services provided include caller ID, call waiting, 3-way calling, call hold, voicemail, unified messaging and more.

“Voice over broadband has the potential to disrupt telecom markets around the world,” said Kevin Mitchell, directing analyst, Service Provider Networks and Next Gen Voice, Infonetics Research. “Broadband has serious traction in the market, and carriers are looking to drive additional benefit to customers while enhancing ARPU opportunities. Benefiting from their strong track record in building VoIP networks for leading carriers around the globe, Sonus is well positioned to take advantage of carrier demand for VoBB solutions.”

Sonus access solutions support interworking between various protocols such as SIP, MGCP and H.323 to a variety of devices such as Integrated Access Devices (IADs), Line Access Gateways (LAGs), next-generation Digital Loop Carriers (DLCs) and IP endpoints, all on the same platform. This network flexibility minimizes cost and complexity, while providing feature transparency over many transport technologies.

Proven in major service provider networks worldwide, Sonus’ packet voice solutions currently carry more than 7.5 billion minutes of voice traffic per month. Designed for 99.999% network availability, Sonus’ platform delivers superior performance and reliability, functioning in both centralized and globally distributed configurations.

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 Open Services ArchitectureÔ (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking and tandem switching, residential and business access, network border switching and enhanced services. Sonus’ voice infrastructure solutions, including media gateways, softswitches and network management systems, are deployed in service provider networks worldwide. Sonus, founded in 1997, is headquartered in Chelmsford, Massachusetts. Additional information on Sonus is available at http://www.sonusnet.com.

This release may contain projections or other forward-looking statements regarding future events or the future financial performance of Sonus 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 “Cautionary Statements” section of Sonus’ Quarterly Report on Form 10-Q, dated November 10, 2003 and 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, uncertainties regarding the timing of the Company’s completion of the audit and filing of its Annual Report on Form 10-K/A for 2003 and future periodic reports, the possibility that Sonus may be delisted from Nasdaq, risks as to the litigation and SEC investigation with respect to the foregoing and related matters, unforeseen issues encountered in the completion of the audit, uncertainties regarding the extent to which prior period financial statements will be restated, the continued adverse effect of developments in the telecommunications industry, Sonus’ ability to grow its customer base, dependence on new product offerings, market acceptance of its products, competition from large incumbent vendors, rapid technological and market change and manufacturing and sourcing risks. In addition, 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. Open Services Architecture, GSX9000, Insignus and Sonus Insight are trademarks of Sonus Networks. All other trademarks, service marks, registered trademarks, or registered service marks are the property of their respective owners.