Recently I came across a strange problem which I thought I would share.
The scenario is Lync Server 2013 Standard edition and Lync Server 2010 Mediation server(in process of migrating). The problem started when a user reported that he wasn’t able to receive incoming PSTN calls. Outbound calls was working just fine.
I started investigating the problem and ran some tracing with Wireshark on the Mediation server along with Lync Server logging tool. The Wireshark traces showed that the Lync Mediation server was sending “487 – Request terminated” to the PSTN gateway after receiving a CANCEL.
Snooper logs was showing the same messages and also in some cases “504 – Server timed out”. The Lync Monitoring server had no records of the call beeing established at all. After checking with the service provider of the PSTN gateway and doing some thorough checks of the unassigned numbers and all other kind of stuff(including the use of this script from a colleague to check all registered telephone numbers used in Lync and other systems), I was left in the dark. There was no reason for this not to work as it should.
Solution: Rebooted the Lync 2013 FrontEnd server, and everything worked like a charm.
Key takeaway from this post: When in doubt, reboot 🙂