SIP Trunk and outbound calls - Will NAT work? RRS feed

  • Question

  • Hi,

    We have a colocated mediation server on our Front end Lync server.  All other servcies work as expected, including inbound calling and conferencing.  Outbound to external tel numbers just stops after the connection is made to the SIP Trunk provider.  The reason is the contact record contains our internal mediation server name, and not a public IP that the firewall is listening on. 

    I am using 1 IP for the server where the mediation server is on, and have a firewall rule allowing conenctions on port 5060.  So inbound works, but the provider cannot validate that outbound calls originates from us, because our call to them does not contain the correct IP (Maddr).

    So the question is, do I need a publically routeable IP, and do I then have to enter it on the PSTN IP when configuring the medation server?  Everything is running Hyper-V, so I will need to do a few tweaks to get it to work if this is the case.  I was curious, as our provider specifically asks, when registering the service, if our mediation server is using NAT.  So it sounds like it is supported, but maybe I am way off.  I looked and could not find it in the documentation anywhere.....

    Any help appreciated


    Thursday, March 31, 2011 6:25 AM


  • Sounds like no one knows, and I have not found any documentation on what is required when using a ITSP.  Even though the provider had a setting for "mediation server uses NAT", it still did not work.

    I therefore installed a new mediation server in the DMZ, and assigned it a public IP, and now it is working.  Inbound and outbound calling.

    • Marked as answer by stephanhuman Wednesday, April 6, 2011 2:17 PM
    Wednesday, April 6, 2011 2:17 PM