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Lync 2010 and Cisco AS5300 call hold issue

    Question

  • Hello! We have a Lync Server 2010 with Enterprise voice implemented. We have received a sip-trunk from our ITSP (local ukrainian one) to be able to reach PSTN. The incomming and outgoing calls work fine. Except one thing - it is not possible to place a call on hold.

    If we place a call to/from PSTN on hold the Lync client says that it is not possible to place the call on hold and turns the speakers and mic off. After turning the mic and speakers on, the caller and callee cannot hear each other. The call hold on lync-to-lync calls works fine. The only problem is with PSTN calls.

    There are no errors in logs on the lync client and lync server (both front-end and mediation server). At least i can not recognize them.

    We are connected the the local ukrainian ITSP not listed in the Open Interoperability Program (as there are no certified ITSPs in our country). The ITSP uses Cisco AS5300 hardware.

    Any help will be appreciated.


    Tuesday, October 11, 2011 10:20 AM

Answers

  • In your case, Lync is sending a SDP with media=inactive to the Gateway/SIP trunk and is expecting the same SDP in a 200 reply

     

    However, the SDP response from ITSP doesn't contain "media=inactive" that's why Lync client is throwing the "hold" error and is muting the mic/speaker instead.

     

    I had similar issues once, when tried interconnecting to IPOffice pbx through a SIP trunk. In my case, the SBC vendor was able to properly internetwork HOLD messages between two systems and got it working.

    Thursday, October 13, 2011 2:43 AM

All replies

  • Hi,

    This happens because of incompatible Gateway or PSTN Connection. Basically when you hold a call in Communicator, what happens is that Mediation Server sends another INVITE request to the gateway/PSTN to do the hold for LYNC. You can see this if you run Wireshark on the mediation server.

    If your GW/PSTN does not support this, you won't be able to use call hold. This is the main reason that Microsoft recommend to use a GW or a Service provider that supports LYNC (There aren't many). Please refer to the below link for Microsoft Recommended Gateways and devices for LYNC.

    FYI, i don't see the CISCO hardware that your Service Provider use in the list.

    http://technet.microsoft.com/en-us/lync/gg131938#tab=4

    Thamara.

    Tuesday, October 11, 2011 12:55 PM
  • Thanks, Tamara.

    I have seen that our ITSP uses not certified gateway. But i thought there might be a workaround.

    Guys, has anyone faced the problem like mine?


    • Edited by EvgePr Wednesday, October 12, 2011 12:12 PM
    Wednesday, October 12, 2011 12:11 PM
  • In your case, Lync is sending a SDP with media=inactive to the Gateway/SIP trunk and is expecting the same SDP in a 200 reply

     

    However, the SDP response from ITSP doesn't contain "media=inactive" that's why Lync client is throwing the "hold" error and is muting the mic/speaker instead.

     

    I had similar issues once, when tried interconnecting to IPOffice pbx through a SIP trunk. In my case, the SBC vendor was able to properly internetwork HOLD messages between two systems and got it working.

    Thursday, October 13, 2011 2:43 AM
  • Adminiuga, thank you very much for your help!

     

    Thursday, October 13, 2011 8:20 AM
  • Just off the phone from Cisco Support.  This is because the Carrier does not send back the A=Inactive attribute within the 200 OK SDP. 

    upgrade the IOS to 15.2(1)T or 15.2(1)TX which has the new feature of Mid-call Re-INVITE Consumption:

    FYI: http://www.cisco.com/en/US/docs/ios-xml/ios/voice/cube_proto/configuration/15-2mt/cube-midcall-reinvite.html.

     

    You need to to configure following:

     voice service voip

    sip

    mid-call signaling passthru media-change

    Wednesday, September 05, 2012 5:19 AM