Integrating Telephony And Voice Mail Routing

A data processing system comprises call processing logic comprising a voice mail subsystem, or a call management subsystem configured to process voice-over-IP (VoIP) calls, or both a voice mail subsystem and a call management subsystem; service advertisement logic coupled to the call processing logic and operable to send one or more service advertisement messages by unicast to a remote peer data processing system that is also configured with compatible service advertisement logic, wherein the remote peer data processing system is located in a different LAN segment than the data processing system; and each service advertisement message comprises one or more network addresses associated with the call processing logic, and one or more data sets each comprising an identifier value, a first value that indicates that the identifier value is associated with a telephone extension, and a second value that indicates that the identifier value is associated with a voice mailbox.