Nortel Networks NN10029-111 manual Nortel Networks Confidential Overview

Nortel Networks Confidential Overview 23

transmits the following information over a data link to a voicemail server:

•the called number (terminating party's telephone number)

•the calling number

•the type of call forwarding (for example, due to a busy line, an unanswered call)

This feature also provides an interface to pure IP solutions that use a SIP-enabled voicemail server. In this case, SIP messages provide the context data for each call needed by the voicemail server to record a voicemail message. Thus, a SIP-enabled voicemail server accepts Invites for calls routed to voicemail and sends Notify messages for MWI information. The software uses Real-Time Transport Protocol (RTP) to carry the voice media.

There are two configurations through which the SIP Application Module supports voicemail:

•A pure IP, third-party, SIP-enabled voicemail server that uses RTP to establish the voice path from the subscriber to the voicemail server while SIP provides the setup and MWI information.

•A legacy voicemail server that uses a SIP/PSTN gateway to establish the voice path from the subscriber to the PSTN-based voicemail server. The Simplified Message Desk Interface (SMDI) protocol provides the setup information. The platform uses any voicemail server that supports the SMDI protocol. There are two supported physical connections: a line-based gateway and a PRI/T1-based gateway.

Using either of the above configurations, there are three primary scenarios that this feature considers:

•MESSAGE DEPOSIT: An incoming call for a subscriber gets routed to voicemail because the called subscriber is unavailable, busy, or has all calls forwarded to voicemail.

•MESSAGE NOTIFICATION: The voicemail server sends an MWI status update to the SIP Application Module for a particular subscriber. The SIP Application Module then sends a message to the client(s) to update its MWI display.

Note: Clients do not store the MWI state. Only the Presence Module stores the state. When a client registers with the proxy

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