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Implementation Agreement 1.0 Establishes Baseline for Interoperable Internet Telephony Applications

SAN RAMON, Calif., April 1, 1998 - The International Multimedia Telecommunications Consortium (IMTC) today announced that its members have approved the Voice over IP (VoIP) Interoperability Implementation Agreement (IA 1.0). The goal of this specification, which was developed by the IMTC VoIP Forum, is to support two party voice and voice-band calls over IP networks.

The VoIP IA 1.0, now an official IMTC document, seeks to ensure interoperability by defining common functions that will enable products complying with the specification and its references to interoperate. IA 1.0, based on the International Telecommunications Union (ITU) H.323 standards, includes other telephony-specific requirements such as DTMF data transfer and reproduction, and IP specific needs such as directory services and dynamic IP address resolution mechanisms.

"Multiple vendors now offer H.323-compliant client software to support voice over IP networks, but existing applications are not always compatible due to fundamental differences in vendors' voice coding, silence compression, addressing and related functions," said Stephen Thomas, TransNexus chief technology officer and chair of the IMTC VoIP Forum. "The definition and implementation specifications IA 1.0 provides to vendors move the industry that much closer to universal compatibility."

The IMTC VoIP Forum intends to extend VoIP interoperability agreements to include security, billing and settlements, and multi-party calls, among other items. The IMTC VoIP Forum first agreed to establish interoperability guidelines in November 1996 and worked on the IA throughout 1997. The official IMTC ballot on IA 1.0 was distributed in December 1997. An electronic copy of the IA 1.0 document is available on the IMTC FTP Web site at In order to become an official IMTC document, an IMTC Activity Group must first approve a document by a simple majority. Once approved, the document is brought to the entire IMTC membership for ballot.

About the IMTC

The IMTC ( is a non-profit organization promoting the ongoing development and adoption of international standards for voice, data and video conferencing. The San Ramon, California -based consortium's membership includes more than 145 companies from around the globe. Membership is open to any interested party, including vendors of audio, document, and video teleconferencing hardware and software, communications companies, teleconferencing service providers, end users, academic institutions, government agencies and non-profit organizations. The IMTC VoIP Forum is comprised of IMTC Members committed to fostering the development of quality, interoperable packet voice applications over IP through the two-way process of feeding unique technical contributions into appropriate standards bodies, and of referencing appropriate liaison activities.