Avistar Awarded Patent for Video Storage Area Networks; 66th Patent Added to Revenue-Generating Patent Portfolio.

REDWOOD SHORES, Calif. -- Avistar Communications Corporation (Nasdaq:AVSR), a provider of business video collaboration solutions and technology, and Collaboration Properties, Inc. (CPI), its wholly owned intellectual property subsidiary, today announced that CPI has been granted its 66th patent. This patent covers storage management, playback, and distribution of recorded video (based on capacity and bandwidth constraints) over a networked array of servers and storage disks.

US Patent No. 6,816,904, granted November 9, 2004, covers a system of video workstation endpoints, such as Avistar's desktop video endpoints, which are used to create and play back video content, combined with a server-based storage system consisting of storage cells including disk drives and a converter (format, encoding or protocol). The system intelligently decides where files are stored and whether to replicate and distribute copies of files, expanding the capacity to simultaneously play back multiple independent sessions of the same content. Multimedia files, including animations, may also be incorporated in extended file types that include video. Avistar customers benefiting from this technology have improved ability to store, play back and publish video content, regardless of location.

"Recorded video is fast becoming a vital part of rich-media communications," said Dr. Anton F. Rodde, president, Collaboration Properties Inc. "Effective storage management, playback and distribution of video files are essential when working with video. Through our licensing and partnership program, Avistar and CPI are enabling industry players to use Avistar's storage area networks technology to deliver quality video and extend multimedia recordings to end-users."

The Avistar system, managed by the AvistarVOS video operating system, includes the capability to record and playback video from any of its video endpoints. Video can be used to record meetings and leverage experts such as research analysts who can record and distribute updates in near real-time to thousands of people. It can be used for product training, education, and other applications. The system enables users to publish recorded content to web servers and email so that anyone with a browser can benefit from recorded video. By making both the recording and playback of video simple, scalable, and part of video enabling business, Avistar allows its customers to streamline operations and differentiate themselves with rich-media communications.

CPI continues to pursue patents related to video and rich media collaboration technology, and is making its intellectual property portfolio and Avistar technology available to interested companies through licensing and partnership agreements. Under a recent agreement, CPI's intellectual property portfolio was licensed to Polycom, Inc. Announced by both companies on November 15, 2004, the arrangement included a cash payment by Polycom of approximately $21 million dollars, net of contingent legal fees, a settlement agreement and a cross-licensing agreement for all of Polycom's and CPI's patents (including additional patents issued within five years of the agreement date). This cash amount will be accounted for by Avistar as licensing revenue, and recognized pro-rata over a five-year period commencing on the agreement date.

About Avistar Communications Corporation

Avistar develops, markets, and supports video collaboration solutions for the enterprise, all powered by the AvistarVOS(TM) software. From the desktop, Avistar delivers TV-quality video calling, recording, publishing to web and emails, video-on-demand, broadcast origination and distribution, and document sharing. Avistar delivers on vBusiness -- video-enabling business -- by integrating visual communications into the daily workflow and connecting communities of users within and across enterprises. By offering both IP and circuit-switched products, which are fully interoperable, Avistar provides customers with a unique choice of how they implement high-quality video.

Founded in 1993, Avistar Communications Corporation is headquartered in Redwood Shores, California, with sales offices in New York and London. Avistar's technology is used in more than 35 countries. Collaboration Properties, Inc., a wholly owned subsidiary of Avistar Communications Corporation, holds a current portfolio of 66 patents for inventions in primary areas of video technology, including Avistar's video operating system and networked video collaboration products in both digital and analog networks. For more information, visit www.avistar.com.

About Collaboration Properties Inc.

Collaboration Properties Inc. (CPI) is a wholly owned subsidiary of Avistar Communications. Initiated over 10 years ago, CPI's patent program has resulted in an extensive portfolio of patents related to video and rich media collaboration technology. CPI's patent program, combined with Avistar's vision to video-enable how people work via the desktop, has produced a powerful architecture and a broad suite of products and patents. CPI continues to pursue patents for presence-based interactions, desktop video, recorded and live media at the desktop, multimedia documents, data sharing, and a rich-service network video architecture to support Avistar's product suite and customers. CPI is making available this intellectual property and video-enabling technologies through the licensing of its patent portfolio and AvistarVOS operating system technology to companies in the video conferencing, rich media services, public networking, and related industries. Inquiries regarding CPI's product and patent licensing program may be directed to Paul Carmichael, Primary Licensing Advisor, by arrangement with Amanda Redd of CPI, at 650-610-2900.

Cautionary Statement

This press release contains forward-looking statements, including statements regarding the impact of Avistar and CPI technology on the video communications industry, the possible issuance to CPI of additional patents related to video and rich media collaboration technology and future licensing of such technology by industry participants. These statements are subject to various risk factors including, without limitation, market acceptance of Avistar's products and technologies and competition from existing and new video communications providers. We refer you also to the documents that Avistar files from time-to-time with the Securities and Exchange Commission, in particular the section entitled "Factors Affecting Future Operating Results" in Avistar's annual report on Form 10-K and its quarterly reports on Forms 10-Q.

Copyright (c) 2004 Avistar Communications Corporation. All rights reserved. Avistar, AvistarVOS, vBrief, and the Avistar logo are trademarks or registered trademarks of Avistar Communications Corporation.