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Problem Where Caller Audio is not Heard RRS feed

  • Question

  • I have an odd problem that I don't know where to start. On most of our outbound PTSN calls (via a SIP Trunk, mediation bypass is disabled), we cannot hear the answering party until we make a noise on our end. So on an outbound call, the Lync user has to say hello before they can hear the other party. We often end up in the situation of the other side answering the call and then hanging up because our Lync users do not get any audio.

    In a likely related issue, when we hold a large Lync conference, if a Lync user remains silent for 15 minutes, the audio from the conference drops out. The user is not disconnected from the conference but cannot hear anybody else. Once the user unmutes and makes a sound in their microphone, the audio comes back.

    Any idea where this is coming from?

    Monday, December 12, 2011 7:52 PM

All replies

  • Dear Friend, 

    Please Explain what type of PSTN Environment you have. Like Architecture of yours . And the how your call going to outside party? Then we can get idea about your problem. 

    If the gateway front ending may be that's the problem, But without clearing design cant get exact idea.


    Madushka Dias : MCITP(Lync Server 2010 Administrator) & MCTS - Active Directory) - http://uctechi.blogspot.com/ | Live - madushka@live.com | If got your answer don't forget to Rate as an Answer
    Tuesday, December 13, 2011 1:53 PM
  • Hi,

    can you elaborate more on the Enterprice Voice setup in your Lync deplyment? what is the Gateway that you use or there's no Gatway at all?

    also run the Wireshark on the mediation server and check wthether the G711 A-Law and U-Law is enabled in the PSTN side as well as in the gateway. Usually single sided voice issues are caused by Media codec negotiation faliure.

     


    Thamara. MCTS, MCITP Ent Admin, Specialized in U.C Voice OCS 2007 R2
    Tuesday, December 13, 2011 4:07 PM
  • We have a standard edition Lync Server with the mediation server colocated. We are connecting to the PSTN via a SIP Trunk gateway to CircuitID so there is no gateway device on our end.
    Tuesday, December 13, 2011 5:56 PM
  • Hi,

    Do you Enable the call admission control?

     If yes, please disable it and check if the problem occurs again.

    If still can not work, you'd better get the logs with wireshark or lync server logging tool.


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

    • Proposed as answer by Sean_Xiao Tuesday, December 20, 2011 6:18 AM
    • Unproposed as answer by NWofford Wednesday, December 21, 2011 3:41 PM
    Wednesday, December 14, 2011 8:21 AM
  • Disable refer support on the Lync trunk configuration and see if it makes any difference.
    ------Exchange, OCS------
    Wednesday, December 14, 2011 11:52 AM
  • Hi,

    Do your question is solved?


    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

    Monday, December 19, 2011 9:36 AM
  • Possibly an isue with your firewall rules for media traffic. How does the SIP trunk terminate in your environment? Public address on the mediation server? or do you NAT through a firewall? if so, what kind of firewall and do you have SIP ALG functionality enabled?

    Cheers,


    Damo

    Wednesday, December 21, 2011 12:16 PM
  • Refer support and call admissions control were already disabled. The SIP trunk terminates through a NAT address through a Forefront TMG 2010 firewall.
    Wednesday, December 21, 2011 3:41 PM
  • terminating the SIP Trunk through a TMG is not a good method and not a best practice. can you get the SIP Trunk to directly terminate on the Mediation server and see wthether you get this problem? i suspect that this issue is there because of the the TMG.

     


    Thamara. MCTS, MCITP Ent Admin, Specialized in U.C Voice OCS 2007 R2
    Wednesday, December 21, 2011 4:12 PM
  • So best practices is to have the Front End Server (with co-located Mediation Server) located outside our firewall?
    Wednesday, December 21, 2011 8:03 PM
  • No. best practice is to collocated Mediation server (depending on the capacity) with 2 NIC s and get the Mediation server to use a seperate NIC to listen to the SIP trunk which might be on some other subnet.

    none of the FE server or Mediation server are recommended to be put on the DMZ. The EDGE will stay there,


    Thamara. MCTS, MCITP Ent Admin, Specialized in U.C Voice OCS 2007 R2
    Thursday, December 22, 2011 1:44 AM
  • Only the Edge should be middle of Firewall.. 

     


    Madushka Dias : MCITP(Lync Server 2010 Administrator) & MCTS - Active Directory) - http://uctechi.blogspot.com/ | Live - madushka@live.com | If got your answer don't forget to Rate as an Answer
    Wednesday, December 28, 2011 4:45 AM
  • Hi

    Are you still facing this issue or resolved.

    Front end server and mediation server colocated with sip trunk provider is not recomended.

     

    -Jiten

    Thursday, January 5, 2012 11:37 AM