Avistar Communications Receives NASDAQ Delisting Notice Due to Delayed Form 10-K; Request for Hearing Filed.

REDWOOD SHORES, Calif. -- Avistar Communications Corporation (NASDAQ:AVSR), a video collaboration platform provider, today announced that on April 18, 2006 it received a notice from the staff of The NASDAQ Stock Market stating that Avistar is not in compliance with Marketplace Rule 4310(c)(14) because it has not filed its Annual Report on Form 10-K for the year ended December 31, 2005 (the "2005 Form 10-K") on a timely basis. The notice is automatically generated by NASDAQ, and indicated that due to such noncompliance, Avistar's common stock will be subject to potential delisting. Avistar has requested a hearing before the NASDAQ Listing Qualifications Panel (the "Panel") to appeal the NASDAQ staff's determination. The hearing request will automatically stay the delisting of Avistar's common stock pending the Panel's review and decision. There can be no assurance, however, that the Panel will grant Avistar's request for continued listing. Until compliance with NASDAQ's Marketplace Rules is re-established, the trading symbol for Avistar may be changed from AVSR to AVSRE by the NASDAQ Capital Market.

As previously announced, the filing of the 2005 Form 10-K has been delayed due to an on-going review of the Company's 2004 Annual Report on Form 10-K by the U.S. Securities and Exchange Commission (SEC). Avistar and its independent registered public accountants are working diligently to resolve the SEC's comments, and file the 2005 Form 10-K shortly thereafter.

About Avistar Communications Corporation

Avistar Communications Corporation develops, markets, and supports a video collaboration platform for the enterprise, all powered by the AvistarVOS(TM) software. From the desktop, Avistar delivers business-quality video calling, recording, publishing to web and e-mails, video-on-demand, broadcast origination and distribution, and document sharing. Avistar video-enables business processes by integrating visual communications into the daily workflow and connecting communities of users within and across enterprises. Founded in 1993, Avistar 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. (CPI), a wholly owned subsidiary of Avistar, holds a current portfolio of 70 patents for inventions in the primary areas of video and network technology. CPI pursues 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 offers licenses to its patent portfolio and Avistar's video-enabling technologies to companies in the video conferencing, rich-media services, public networking, and related industries.

For more information, visit www.avistar.com.

Forward Looking Statements

This press release contains forward-looking statements, including statements regarding the possible delisting of Avistar's stock, stays or other delays in the delisting process, and the filing of Avistar's Annual Report on Form 10-K for 2005. These statements are based on current expectations and assumptions as of the date of this press release, and involve a number of risks and uncertainties, which may cause actual results to differ significantly from such estimates and assumptions. The risks include, but are not limited to, the risk that Avistar is unsuccessful in obtaining a stay in the delisting of its common stock, and the risk that Avistar is unable to resolve the SEC's comments and file its 2005 Form 10-K in the near future. Other risks are set forth in the section entitled "Risk Factors" under "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operations" in the Company's quarterly report on Form 10-Q for the quarter ended September 30, 2005.

Copyright (C) 2006 Avistar Communications Corporation. All rights reserved. Avistar and the Avistar logo are trademarks or registered trademarks of Avistar Communications Corporation.