On the heels of America Online's public resistance in following an open protocol system for instant messaging, AltaVista Co., Monday unveiled an instant messaging service designed to be compatible with similar online services.

According to Bill Keenan, AltaVista senior director of tools, the AltaVista Messenger service utilizes Tribal Voice's PowWow technology. While that technology is compatible with AOL's, the company has blocked users of the PowWow-based services from its network.

Keenan emphasized, however, that AOL's resistance is not the larger issue.

"Whether or not AOL plays ball, we feel that there is a large and attractive market out there. Our service is the best offering available and we intend to market that service to existing, viable audiences," he said.

The AltaVista Messenger reflects the company's commitment to providing users with an product that is interoperable with other leading services on the Internet, Rod Schrock, AltaVista president and chief executive officer, said in a statement.

"Our free service provides the benefit of rich features and multiple communication modes without imposing limitations on the users with whom they may communicate," Schrock said.

The product allows Internet users to exchange messages in real-time without the use of an email inbox. Product features include universal buddy lists and simultaneous, real-time text and voice chat.

AltaVista and Tribal Voice are members of the FreeIM.org industry consortium, which promotes an open protocol system for instant messaging so that users of all services can communicate with one another despite their choice of software.