When a SIP Integration is done between CUCM and Unity Connection, MWI sometimes fails to work. I feel SCCP is more easier to troubleshoot when compared to SIP.
SCCP uses MWI Directory Numbers to turn ON and OFF Message Waiting Indicator. But SIP does not use MWI Directory Numbers to turn ON and OFF MWI. Unity Connection sends SIP NOTIFY Message to Cisco Unified Communication Manager.
- Login to Cisco Unified Communication Manager
- Go to Device > Trunk > Verify that Unity Connection Trunk configured on CUCM has Inbound CSS configured. The inbound CSS should have the Partitions of the Directory Numbers configured.
- Go to System > Security > SIP Trunk Security Profile > Verify the Profile configured/used by the Unity Connection Trunk has the following parameters checked.
Accept out-of-dialog refer
Accept unsolicited notification
Accept replaces header
- Login to Cisco Unity Connection > Users > Search for the user for whom MWI is not working
- Go to Edit > Message Waiting Indicators > Reset MWI for the Subscriber/Voicemail Box
Now the MWI Light should be turned ON.