This document describes Message Waiting Indicator (MWI) issues, which are a common problem reported when you configure a PBX IP Media Gateway (PIMG) or T1 Media Gateway (TIMG). This configuration can be tricky because it is not completed as often as CallManager integrations.
Notice 503 Service Unavailable in this trace. This is an indication that PIMG/TIMG receives the request, but does not have the resources to deal with it. The rtGetOutboundRout() is an indication that it cannot find a route to the Time-Division Multiplexing (TDM).
If you do not see any '---->NOTIFY' messages in the PIMG/TIMG traces that you gather, this might be an indication of a configuration problem on the Unity Connection. The best method to troubleshoot is to verify the configuration on Unity Connection. Then, enable the Notifier Macro traces on Unity Connection and verify with the Connection Conversation Manager and Connection Notifier traces that MWI processes and requests are sent to PIMG/TIMG.
In order to fix this issue, complete these steps:
Go to the Routing Table and choose Voip Rule > Inbound VoIP Rules.
In the Routing Table, find Outbound Routes.
Find Outbound Destination and set to TDM.
Find Trunk Group and set to TdmAll or the name you created.
Note: This is documented in the Release 10.x guide, but is sometimes overlooked.