So you are setting up inbound dialing to Lync. You make a test call and almost immediately the call disconnects.
What’s that all about?
To find out, fire up the Lync Logging tool and capture all of the levels and flags for the SIPStack component.
Make your call and then analyze the log-file. You should see something similar to the following:
Notice the red lines. This is where you want to dig in. If you read the description in the right hand pane of Snooper, you will find the following text in the ms-diagnostics section near the bottom: The routing rules did not result in a final response for PSTN caller and non-UM enabled callee.
So what does this mean? It means that Lync tried to route the call but couldn’t find an endpoint willing to take the call.
The fix for this is really easy: Fire up the Lync client as the user assigned to that number. Once the user is logged in, an endpoint can be found and Lync will connect the call. A slightly more compete answer would be to enabled Unified Messaging (i.e., Voice Mail) for the user. That way Exchange UM will be the final response for the inbound call.