UPDATED: Analog Device Voice Policy (do not) supported on Skype for Business

Hi all, after the migration from Lync 2013 to Skype for Business 2015 of our production deployment, I receive a call from internal IT for an issue on our analog devices: if they try to call a internal number, no problem. If they try to make an external call, this is dropped suddenly.

Our deployment is very simple, one Skype for Business 2015 Front-End and one Sonus SBC1000 voice gateway, with a E1 ISDN and 8 FXS ports, with 1 FAX and 6 cordless.

I’ve started from the beginning of the call, on the SBC1000: everything was ok, no issue, no alert. Calls from FE to PSTN and vice-versa are ok.
I try to reproduce the issue, the call to and external numebr was dropped istantly.

Fortunately I have the old Lync 2013 FE still online, so I’ve made a test SIP Trunk between SBC and Lync 2013 FE, and in this configuration everything works perfectly, I was able to place the outbound call from the same analog device! So the issue seems to be bound to Skype4B….

It’s time to use ClsLogger, collect some trace and take a look on difference between Lync and Skype4B Analog routing: the “IncomingAndOutgoingCall” Scenario was perfect in this situation.


This is the first packet related to the test call from the analog device to my mobile, as you can see in P-Asserted-Identity field, Lync 2013 correctly associated the incoming call to the analog device SIP URI sip:cordless.test@mysipdomain.com, check the voice policy of the analog device account and route the call according to PSTN Policy and Route. Everything like usual.

…and now… the Skype for Business version…. same call, different results 😦

p-asserted-identity_ko Hey?! WTF?! Where is the P-Asserted-Idendity?!?!? Why it’s NOT correctrly populated? Maybe this is the problem?

The answer is YES, this is the problem, but I’ve opened a ticket to MS support to have an official answer.

After some MS deep tracing and info collection, they sand me these two images to explain the new Skype for Business behaviour with analog devices.



Workaround: MS suggest to apply a PSTN Policy to the Trunk. This will allow the incoming calls from analog device to be routed outside, but it’s now impossible to give different voice policy to different analog devices.

I hope MS will correct this behaviour in future release of Skype for Business.

Best Regards


UPDATE: 25/03/2016

I’ve upgraded our SfB deployment with the latest CU (2016/03) and now the issue seems to be solved! It’s now possible (again) to manage Voice Policy for Analog Devices also.
That’s a VERY GOOD news!


6 thoughts on “UPDATED: Analog Device Voice Policy (do not) supported on Skype for Business

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  1. Assigning PSTN usage policies to a trunk is great if you have a dedicated trunk you can throw all your devices at. Otherwise, assigning a PSTN usage policy to a trunk is a guarantee to break every policy, route, unassigned number rule or forwarding you have working.
    It’s a poor workaround 😦

    Liked by 1 person

    1. I agree, it’s a non-workaround. I’m working on Sonus SIP Manipulation to avoid this issue, I’ll post the complete solution as soon as possible.

      Liked by 1 person

    1. Hi Chris, no other reply from MS, they say that SfB do not consider Analog Device voice policy anymore. MS support took 2 days to answer to that ticket, so the new behaviour is not so clear to them also! The “trunk voice policy” workaround is not so good and a pain if you give different voice policy to different analog devices on the same voice gw (like many of our customers). I’ve done many test to manipulate SIP on voice gw, no way, even if I set P-Asserted-Identity exactly as Lync 2013 does, SfB ignore it. 😦
      At this moment I’ll use a combination of Trunk Voice policy workaround and voice gw rule to try to have Lync 2013 behavior (or something similar).


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