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SIP MWI Relay feature not working with CME 3.x


Core Issue

This problem affects Cisco CallManager Express (CME) 3.4.

This is the affected call flow:

Cisco Unity -> CME performing Message Waiting (MWI) relay -> different CME endpoints with Session Initiation Protocol (SIP)

This problem also affects the following call flow:

SIP MWI server (CME 3.2 or 3.3) ---- SIP MWI Client (CME 4.0)

Cisco Unity does send the MWI message, and the Cisco CallManager Express (MWI relay) does receive it and attempt to relay the message to the Cisco CallManager Express endpoints. However, that call leg/transaction does not exist.

This problem id documented by the bug-Id: CSCse52710

Ephone-1 is registered to CME END, and a voice message can be left for ephone-1. Ephone-1 is able to retrieve voicemail from Cisco Unity. However, there is no MWI present when the message is left.


According to RFC3265, the MWI server must run 12.4(6)T. If 12.3(14) T6 is run, it must be upgraded.

When the MWI server sends a NOTIFY message, it does not include the subscription-state header. According to the RFC, this is mandatory. That is why the MWI client replies with a BAD request. To fix the issue, upgrade the MWI relay server to 12.4(6) T.

For more information, refer to Programming Multiple Cisco Unified CallManager Express Routers to Integrate with a Single Cisco Unity Server.