Call Loop on Lync in case of unallocated number


I saw that lync 2013 make a Loop when it receive a call from PSTN (with the right format E164) toward a number not yet associated to a Lync User. Lync  send back the call to the PSTN Gateway which generate a Loop.

I know that there is a Unassigned number feature but with the large range of number managed by lync in my network i cannot manage every day to change the range of number not yet assigned. Sometime i have only 5 or 10 numbers really associated to Lync users over a range of number of 100 possible numbers.  I should  find a way when the call is received from PSTN Gateway   to release the call if the called is not a user lync .

Any solution ?

September 1st, 2015 2:47pm

Lync shouldn't make a call loop by default.  Do you have PSTN usages assigned to your trunk?  If so, that may very well be the issue. 

To check, in the Control Panel, go to Voice Routing -> Trunk Configuration and see if you have PSTN usages assigned.   If you have them in there, but you're not intentionally trying to loop calls back out (perhaps to another PBX), you can remove them and test again.

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September 1st, 2015 3:53pm


Agree with Anthony Caragol.

On Lync Server Control Panel--Voice Routing--Trunk Configuration, when you want to achieve the function of inter-trunk routing, then you need to associate and configure PSTN usage records to the special trunk configuration.

So you can try to disable this option if you have enabled it before, and then have a test.

You can refer to the link below:

Best Regards

September 1st, 2015 10:18pm

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