Lync M:N Routing Breaks AnalogDevices

OK, so that’s not entirely the truth – but the great Scott Hanselman says you need to have a catchy title to get ’em in.

*IF* however, you implement M:N Routing in Lync 2013 and change the trunk name so that it’s no longer the same as the gateway’s FQDN, you’ll no longer be able to call a Cs-AnalogDevice that uses that PSTN/trunk gateway:


“Call was not completed or has ended. When contacting your support team, reference error ID 503 (source ID 241).”

Snooper reports it thus:


“SIP/2.0 503 Service Unavailable”. “Analog device configured on an unknown gateway”

This will Work:


The trunk name = the FQDN of the Gateway.

This will break it 100% every time:



PSS is working on the case. They’ve been able to dupe it, so we’re just in the queue for a fix. Stay tuned.


Credit where it’s due – my colleage Dan nailed this one. I’m just the messenger. Thanks Dan!


  1. Just fallen in this hole with SfB 2015 CU3, wasted a good few hours trying to work out how I’d broken the Analogue devices. Found this article an voila, going again. I have cheated and added the gateways using an alias which I now also use on the analogue device.

    • Hi Michael. Alas it’s a case of “the more the miserabler”. Yes, if one trunk shares the same FQDN as the Gateway you’re good to use it for your analogs, but if you try to use any of the extra ones as the -gateway for a CsAnalogDevice you’ll encounter the same situation documented above.

      – G.

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