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NexTone's Multiprotocol Signaling Switch Running Live with Sonus' OSA in MASERGY Network; Provides SIP to H.323 Interworking for Connectivity with Enterprise VoIP Systems

WESTFORD, Mass. and ROCKVILLE, Md., July 16, 2002 - Sonus Networks (Nasdaq: SONS) and NexTone Communications today announced that NexTone has attained Platinum standing in Sonus' Open Services Partner AllianceSM (OSPA). To reach the Platinum level, the top tier in the Alliance, OSPA partners must meet several criteria, including deployment in a live, revenue-generating service provider network together with one or more Sonus products. Masergy Communications, a global provider of customer-controlled network services, has implemented NexTone's Multiprotocol Signaling Switch (MSW) with Sonus' voice infrastructure solutions to deliver SIP/H.323 voice services to enterprise customers.

"Our mission is to deliver a full suite of voice, data and video services to the global enterprise market," said Kenneth Frank, MASERGY's senior vice president of engineering and systems. "The combined solution provided by Sonus and its OSPA partner NexTone provides a key component to our voice service offering, and allows us to cost-effectively provide SIP-based voice services to enterprises, regardless of their infrastructure. We are extremely pleased to be working with Sonus and NexTone as we move forward in our drive to offer customers fully integrated converged network services."

MASERGY is rolling out a global converged network using Sonus' Open Services Architecture (OSA) as the foundation for delivering voice services. MASERGY has deployed all elements of the award-winning OSA, including the GSX9000 Open Services Switch, the Insignus Softswitch, and the Sonus Insight Management System. With the Sonus-based VoIP network, MASERGY offers business users traditional voice services such as long distance, international and local calling services. Additionally, MASERGY can leverage the advanced IP/MPLS infrastructure to deliver a host of next-generation, SIP (Session Initiation Protocol) voice services to enterprise customers.

To facilitate the delivery of SIP services to enterprises that use H.323, MASERGY has deployed the NexTone Multiprotocol Signaling Switch (MSW). Enabling the service providers to launch new business initiatives, the NexTone MSW eliminates technical barriers, such as SIP/H.323 signaling interworking and network security, which hinder service providers' ability to provide direct trunking with enterprise VoIP systems. The SIP/H.323 interworking function and VoIP firewall control capability of the MSW gives service providers such as MASERGY a flexible, secure and cost-effective way to interconnect their SIP network with a variety of enterprise VoIP solutions.

"NexTone and Sonus provide carriers, such as MASERGY, with a robust end-to-end solution for VoIP-based services," said Dan Dearing, vice president of marketing, NexTone Communications. "Our joint solution eliminates the complexities of delivering basic and valued-added VoIP services to the enterprise, and enables MASERGY to quickly and uniquely address the growing VoIP needs of its enterprise customers."

"Our partnership with NexTone is critical in enabling MASERGY to provide a full range of traditional and next-generation telephony services to enterprise customers," said Gary Rogers, vice president of worldwide sales, Sonus Networks. "Further, our deployment together in the MASERGY network underscores that packet-based voice services continue to gain momentum in the market and offer service providers a competitive advantage. We are pleased to welcome NexTone to the growing list of Sonus Platinum partners."

About Sonus' OSPA

Sonus Networks' Open Services Partner Alliance Program provides a framework that offers service providers end-to-end packet-based network solutions using best-of-breed technologies and applications. The goal of the OSPA is to empower standards-based interoperability between applications, hardware vendors, and the Sonus product family. An integral part of the Sonus OSPA, the OSPA Interoperability Laboratory is the first in the industry where product interoperability is verified, trial testing is performed and complete solutions are ultimately produced. To find additional information on the OSPA, including a list of all OSPA partners, log on to http://ospa.sonusnet.com.

About NexTone Communications

Powering the Virtual Central Office, NexTone Communications is a leading provider of VoIP infrastructure for service providers and carriers. NexTone's Multiprotocol Signaling Switch allows service providers and carriers to interconnect their voice networks in the most simple and cost effective way. Corporate headquarters are located in Rockville, Md. with sales offices nationwide. NexTone Communications is a Safeguard Scientifics (NYSE: SFE) partner company. For more information, visit www.nextone.com.

About Sonus Networks

Sonus Networks, Inc., is a leading provider of packet voice infrastructure products for the new public network. With its Open Services Architecture (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 Sonus' Quarterly Report on Form 10-Q, dated May 10, 2002 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 emerging 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.

Open Services Partner Alliance is a service mark of Sonus Networks. Open Services Architecture, GSX9000, Insignus and Sonus Insight are trademarks of Sonus Networks. All other company and product names may be trademarks of the respective companies with which they are associated.