Unified Messaging Architecture: Taking the Call

Exchange Server 2007 places voice mail into a user’s mailbox. Shown here is a diagram of an external caller phoning into a user’s Unified Messaging (UM)-enabled mailbox. The process proceeds as follows:

(1) An external caller dials a UM-enabled user’s number using a standard telephone on the public switched telephone network (PSTN).

(2) The user’s office telephone rings a few times.

(3) The corporate private branch exchange (PBX) is programmed to route this user’s phone number to the IP/VoIP gateway if there is no answer after a predetermined number of rings.

(4) The IP/VoIP gateway determines the appropriate UM server to contact and converts the voice stream to VoIP protocols: the Session Initiation Protocol (SIP) and Realtime Transport Protocol (RTP).

(5) The UM server determines the appropriate recipient mailbox by matching the telephone extension number to the correct person’s entry in Active Directory.

(6) The UM server plays the mailbox owner’s voice-mail greeting, records the voice message, and attaches it to an e-mail.