Natural MicroSystems and Clarent Team To Pass Stringent SS7 Deutsche Telekom Testing.

Business/Technology Editors

FRAMINGHAM, Mass. & REDWOOD CITY, Calif.--(BUSINESS WIRE)--Oct. 10, 2000

Natural MicroSystems (NASDAQ: NMSS), the technology leader enabling a new era of communications, today announced that it has worked closely with Clarent Corporation (NASDAQ: CLRN) to enable Clarent to successfully complete ETSI (European Telecommunications Standards Institute) Version 2 ISUP (Integrated Digital Services Network User Part) SS7 conformance testing conducted by Deutsche Telekom (DT). This approved solution is comprised of NMS' Signaling System 7 (SS7) Version 3.5 software and TX3220(TM) hardware platform integrated with the Clarent Gateway system. A longstanding NMS customer, Clarent is a worldwide leader in providing carrier-grade, phone-to-phone Internet Protocol (IP) telephony solutions to mainstream carriers and service providers worldwide.

SS7 is the main call-control protocol for the public switched telephone network (PSTN). Carriers require SS7 support to implement IP telephony solutions that connect to the traditional circuit-switched voice network. Carriers and regulators around the world require successful completion of SS7 conformance testing before any device or equipment is certified as eligible to directly connect to the PSTN. Internationally renowned for having the most extensive testing programs of all European carriers, Deutsche Telekom is widely considered to have one of the most critical and desirable approvals to earn. As a result, this approval represents a major milestone for both Clarent and NMS.

"The superb support we have received from NMS has helped Clarent reach an extremely important milestone," said Dr. Peter Bohacek, senior vice president, product marketing, Clarent Corporation. "This announcement is significant as it allows Clarent customers to interconnect directly with DT's network in Germany and opens the door to continued opportunities in the European market."

Clarent currently deploys equipment using NMS' SS7 software in more than 20 countries, including Germany, China and Japan. Its successful testing at DT's T-Nova labs ensures not only an added signaling market presence in Germany but also reinforces Clarent's appeal among carriers considering deployment in other European countries. By incorporating NMS' TX3220 communications platform and SS7 Version 3.5 software, Clarent's equipment benefits from the high availability, high density and SS7 compliance required by the carrier market and critical for the IP telephony gateway industry.

"This has been a remarkable year for NMS as we continue to strengthen and confirm our capabilities to serve the communications market worldwide," said Michel Laurence, vice president and general manager of NMS' New Network Access group. "Clarent is and has long been a very important customer of ours. With Deutsche Telekom's SS7 testing approval, Clarent intends to continue to further its VoIP leadership in European markets."

Leading analyst firm International Data Corporation (IDC) predicts that the IP Gateway industry will climb to $9 billion by 2004, a 25-fold increase since 1999. To take advantage of the opportunity in this exploding market, carriers require field-tested, globally approved solutions offered by companies like NMS and Clarent. Carriers using Clarent's gateways can offer high-quality, high-capacity voice processing solutions that support a wide range of telephony interfaces and provide PSTN voice quality.

NMS offers communications equipment suppliers the confidence that its platforms will pass inspection anywhere, delivering on NMS' commitment to provide the broadest, most powerful range of scalable carrier-grade technology. Today, NMS' robust IP telephony platforms reside at the heart of equipment being deployed in many next-generation systems and networks throughout the world.

About Clarent Corporation

Clarent Corporation (Nasdaq:CLRN) is a global market leader in providing intelligent, software-driven products throughout IP-centric communications networks, serving more than 300 telecom service providers worldwide such as AT&T, NTT and China Telecom. Clarent solutions enable interconnection between communications service providers' networks and foster the creation of global footprints. In addition, Clarent's software platform allows carriers to develop limitless new features for consumers and enterprises. Founded in 1996, Clarent is headquartered in Redwood City, Calif. and has offices in Asia, Europe, Latin America and North America. To learn more about Clarent, visit its web site at www.clarent.com.

About Natural MicroSystems

Natural MicroSystems (NASDAQ: NMSS) is the technology leader making it possible for the world's top networking and communication equipment suppliers to create and accelerate communications infrastructure and services. The Framingham, MA company designs, develops and supplies network-quality hardware and software components and provides design and customization services that are enabling a new era of communications.

Deployed in more than 65 countries, NMS' products and technologies are at the foundation of today's high-value communications systems, including network-based enhanced service platforms, media and access gateways, media servers, voice portals, web-enabled call centers, unified messaging platforms and wireless networks. NMS has a long history of technology innovations that advance the rapid growth of the communications industry worldwide, including breakthroughs such as the first complete open IP gateway, the first complete open packet media server and leadership in bringing open, scalable CompactPCI to the telecommunications industry. More information about NMS is available at http://www.nmss.com.

Forward Looking Statements: This release may contain forward-looking statements that involve risks and uncertainties, including potential issues relating to interoperability, inability to introduce new products, ability to retain customers, changes in market conditions, government regulations, the international communications industry, technological changes and other factors, which could cause actual results to vary materially from those expressed in or indicated by the forward-looking statements. These risks and uncertainties are described further in the risk factors discussed in Clarent's periodic filings with the SEC.

Natural MicroSystems and TX are trademarks of Natural MicroSystems Corporation. Clarent, the Clarent logo, NetPerformer, DynaStar, Clarent Command Center, Clarent ThroughPacket, PowerCell, SkyPerformer, ACTview and ServiceXchange are trademarks or registered trademarks, and "The Clearer. The Better." is a service mark of Clarent Corporation in the United States and other jurisdictions. All other trademarks, registered trademarks and service marks are the property of their respective owners.