In Office Communications Server 2007 R2, meeting invitations provide users with an option to join a conference call using a Web browser. When a user chooses this option, the user joins the conference using the Communicator Web Access client. Communicator Web Access enables users to join the audio portion of the conference by connecting the user’s telephone to the public switched telephone network (PSTN). This is known as PSTN dial-out. If a conference call supports dial-in audio conferencing, Communicator Web Access initiates PSTN dial-out to the dial-in conferencing access phone number to add the user to conference audio.
If you have deployed the Mediation Server and media gateway required to support calls to the public switched telephone network (PSTN), and enabled Enterprise Voice for Communicator Web Access users, no additional configuration is required to support audio conferencing for Communicator Web Access users. However, if you have not deployed Enterprise Voice, you must configure static routes to enable dial-in conferencing for Communicator Web Access users. For procedures, see Configuring Audio Conferencing for Communicator Web Access.