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Outgoing SIP calls issue

    Question

  • Hi,

    I'm having a problem with outgoing calls over a SIP trunk.  The issue doesn't effect all calls (probably about 80% and dialling the same number twice, one call may have the issue, the next may not).  The call dials and connects but there is no incoming audio until you make a noise (say something into the mic) then the incoming audio starts coming through normally and the call is fine from then on.

    The setup is a Single Standard Lync 2013 Server with collocated Mediation Server.  There is no problem with bandwidth etc, as the problem is exactly the same is there are no users on the network.  I have also taken out our firewall and connected the Lync Server directly to the router.  This has no effect.

    The Lync Server is Virtual Machine on a Hyper V Server.  Incoming calls are working fine and haven't had any delay issues with these.

    Hope someone can help!

    Thanks,

    Andy

    Thursday, October 03, 2013 1:04 PM

All replies

  • Take a wireshark trace on the mediation server to understand the issue better.

    Praveen | MCSE Messaging 2003

    Thursday, October 03, 2013 1:15 PM
  • Did you use dual IP addresses for Lync Front Server and collocated Mediation Server?

    The standalone Mediation Server is required if you deploy SIP trunk.

    If you use collocated Mediation Server, you need to use dual NIC on Lync Front End Server.

    The IP address should be in different subnets.


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    Monday, October 07, 2013 5:28 AM
  • Can you explain how the SIP trunk connecting to the Mediation server? what's the Gateway that you're using for the PSTN leg?

    Monday, October 07, 2013 6:13 AM
  • Hi Lisa

    Many thanks for your reply.  I am in the middle of installing a standalone Mediation Server.  Is it safe to connect the External NIC from this server directly to the Internet though?  Or should I NAT from behind my Fortigate Firewall?

    I'm just a bit wary of server not being behind a firewall.

    Thanks,

    Andy

    Monday, October 07, 2013 9:01 AM
  • Hi Thamara

    It's a direct SIP trunk from our Lync Server to our SIP Provider.  We are not using a Media Gateway.

    Thanks,

    Andy

    Monday, October 07, 2013 9:01 AM
  • This could be a problem. unless the SIP Provider is a Microsoft lync certified Provider, there is a higher chance that the problem you currently facing is due to incompatibility of SIP messages between 2 parties. 

    you need to get a certified gateway deployed in between the SIP Trunk and the mediation server. that will most probably fix the problem. check below URL to find out who are the certified providers for Lync Server

    http://technet.microsoft.com/en-us/lync/gg131938.aspx

    Monday, October 07, 2013 9:11 AM
  • Hi,

    I have had confirmation that BT is our Service Provider and they are Lync Certified.

    Installing a standalone Mediation Server has not made any difference to the issue.  I have even tried plugging in the External Interface into our router directly so bypassing our switch and firewall, but again this hasn't made any difference.

    Are there any known issues with Hyper V virtual NICs and Switches?

    Thanks,

    Andy

    Monday, October 07, 2013 4:11 PM
  • Hi Lisa

    Many thanks for your reply.  I am in the middle of installing a standalone Mediation Server.  Is it safe to connect the External NIC from this server directly to the Internet though?  Or should I NAT from behind my Fortigate Firewall?

    I'm just a bit wary of server not being behind a firewall.

    Thanks,

    Andy

    It is not safe to connect the External NIC to Internet directly. You can check the recommendation at

    http://technet.microsoft.com/en-us/library/gg398720.aspx


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    Wednesday, October 09, 2013 6:11 AM
  • Hi,

    It turned out to be our SIP Provider.  Even though they are Microsoft Lync Certified (not sure how).  All the issues we have had were due to the SIP Provider.  Now we have changed and all seems ok. 

    Apart from Music on hold not working when an incoming call is answered through a response group.  When put on hold you hear the hold music for half a second and then nothing.  When being taken off hold you hear another half a second of the music.

    Any ideas with this issue?

    Many Thanks,

    Andy

    Thursday, October 17, 2013 7:43 PM