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Revenues Increase 27% Sequentially, Loss Narrows to $0.02 Per Share

WESTFORD, Mass., April 9, 2003 – Sonus Networks, Inc. (Nasdaq: SONS), a leading provider of voice infrastructure solutions for the new public network, today reported its financial results for the first quarter ended March 31, 2003, in accordance with U.S. generally accepted accounting principles (GAAP).

Revenues for the first quarter of fiscal 2003 were $16.0 million compared with $12.7 million in the fourth quarter of fiscal 2002. Net loss for the first quarter of fiscal 2003 was $4.4 million or $0.02 per share compared with a net loss for the fourth quarter of fiscal 2002 of $12.8 million or $0.07 per share. Revenues for the first quarter of fiscal 2002 were $21.2 million and the net loss for the first quarter of fiscal 2002 was $16.2 million or $0.09 per share.

"Our financial results for the first quarter reflected good progress toward our business objectives," said Hassan Ahmed, president and CEO, Sonus Networks. "We grew our revenues 27 percent over last quarter, and by continuing to manage our business with precision, we further narrowed our net loss. In Q1, we also continued to add new customers around the globe and made important additions to our product family."

During the quarter, Sonus expanded its addressable market with the introduction of its SMARRT Wireless solutions. These solutions include wireless carrier applications such as Gateway Mobile Switching Center (GMSC), Wireless Transit/Tandem Switching and Wireless Long Distance. Sonus' SMARRT Wireless allows carriers to cost-effectively deploy and operate wireless networks, increase network capacity to accommodate growing subscriber traffic, and build new revenue streams and customer loyalty through the delivery of packet-based enhanced services. 

Sonus also began shipping Release 5.0 of its packet voice infrastructure solutions. This latest version of the Sonus Open Services Architecture TM(OSA) provides greater value to service providers in three important areas: new revenue-generating opportunities enabled by a suite of voice VPN services; expanded international capabilities delivered through additional international signaling variants; and network performance optimization provided through a range of enhanced traffic management features. 

Continuing to expand its customer base, Sonus announced that NuVox, an integrated communications provider serving the Midwestern and Southeastern United States, selected Sonus to develop a VoIP network that will carry all of NuVox's long distance voice traffic, as well as offload Internet traffic from NuVox's circuit-switched local voice network. 

Underscoring Sonus' success with both existing and new customers, the company was again ranked the number one provider of carrier-class packet voice equipment for the fourth quarter of 2002. Industry research firms In-Stat/MDR, Infonetics Research and Synergy Research Group named Sonus the market share leader, recognizing Sonus as the top equipment vendor in several major service provider packet telephony market segments. 

Finally, Sonus announced the appointment of Bert Notini, executive vice president and CFO of Manufacturers' Services Limited (NYSE: MSV), to the company's board of directors. Notini has worked with companies in the high tech industry for nearly 20 years. With extensive background in the financial and legal fields, Notini brings invaluable experience and perspective to the Sonus Networks board, particularly in the area of corporate governance. 

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services ArchitectureTM (OSA), Sonus delivers end-to-end solutions addressing a full range of carrier applications, including trunking, residential access and Centrex, tandem switching, and IP voice termination, as well as enhanced services. Sonus' award-winning 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 Westford, 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 Risk Factors" section of Sonus' Annual Report on Form 10-K, dated March 19, 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. These risk factors include, among others, the adverse effect of recent developments in the telecommunications industry, the weakened financial position of many service providers, Sonus' ability to grow its customer base, dependence on new product offerings, market acceptance of its products, 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 is a trademark of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.

(A) These Adjusted Condensed Consolidated Statements of Operations are for informational purposes only and are not in accordance with US generally accepted accounting principles (GAAP). These statements exclude the impact of the write-off (benefit) of inventory and purchase commitments, amortization of stock-based compensation, amortization and write-off of goodwill and purchased intangible assets and restructuring charges (benefit). Sonus' management uses the non-GAAP financial results as an alternative means for assessing our quarterly operations. Even though Sonus' management recognizes that non-GAAP financial results are not a substitute for GAAP results, non-GAAP measures are helpful in assisting Sonus' management understand and manage its business. Please refer to the section entitled Explanation of Use of Non-GAAP Financial Results on page 29 of Sonus' Annual Report on Form 10-K, dated March 19, 2003, which explains in detail the use by Sonus' management of non-GAAP financial results.

(A) These Adjusted Condensed Consolidated Statements of Operations are for informational purposes only and are not in accordance with US generally accepted accounting principles (GAAP). These statements exclude the impact of the write-off (benefit) of inventory and purchase commitments, amortization of stock-based compensation, amortization of goodwill and purchased intangible assets and restructuring charges (benefit). Sonus' management uses the non-GAAP financial results as an alternative means for assessing our quarterly operations. Even though Sonus'management recognizes that non-GAAP financial results are not a substitute for GAAP results, non-GAAP measures are helpful in assisting Sonus' management understand and manage its business. Please refer to the section entitled Explanation of Use of Non-GAAP Financial Results on page 29 of Sonus' Annual Report on Form 10-K, dated March 19, 2003, which explains in detail the use by Sonus' management of non-GAAP financial results.