Office Communications Server 2007 R2 enables users to invite other people, including anonymous users, to participate in instant messaging conferences, audio conferences, and desktop sharing sessions. To enable people to schedule and to join these conferences, Communicator Web Access (2007 R2 release) hosts a pair of Web pages (named, Dialinand Join). Before you can use these pages for scheduling and joining conferences, the URLS must be published to Active Directory. You can do this either when you create a virtual server or later by using the Communicator Web Access snap-in.
For additional details about publishing URLs, see Publishing Communicator Web Access URLsin the Deploying Communicator Web Access (2007 R2 Release) documentation.