One way Audio - Lync / Trixbox RRS feed

  • Question

  • Hidown the trunk from lync to


    I have Lync setup to dial out to the pstn via a Trixbox PBX. I can dialout ok (granted it does take almost 10 seconds before the house phone rings), however when answered they can hear me but I cant hear them. If I use a softphone and make an outgoing call directly from the trixbox from a trixbox extentsion and I get two way audio. I have opened the required ports on the firewall, they must be ok as it works with the softphone. What could be the problem? Is there some kind of NAT'ing issue down the trunk from lync to the trixbox?

    Any ideas?

    Sunday, August 28, 2011 7:31 PM

All replies

  • Hi,NEOband,

    Would you please try adding the line "NAT=yes" on the trunk configuration and see if it works?

    Furthermore you can read through this old thread below,I am sure you will get more hints in it


    If above doesn't work for you,would you also please check your configuration step-by-step with this guide?Just replace the CircuitID gateway with your Trixbox hostname/ip.

     Part 1

    Part 2



    • Proposed as answer by Sharon.Shen Thursday, September 1, 2011 10:34 AM
    Tuesday, August 30, 2011 8:00 AM
  • Hi,NEOband,

    Any updates here?

    If you have fixed it please do let me know.Thanks!



    Thursday, September 1, 2011 10:34 AM
  • Hi

    Yes i have tried those suggestions already and can't work it out. I'm going to spend a hour or so tomorrow, I'll let you know how it goes. However I know know the issue is not with lync as the one way audio is also present with a sip client directly on the Trixbox, so once i work it out hopefully lync will work too.

    Saturday, September 3, 2011 4:23 PM
  • OK,

    Ignore my Lat entry, the issue is only present with Lync call via the Trixbox. Calls made to the PSTN work fine in both ways so it must be something to do with NAT'ing or the trunk setup in Trixbox. This is my trunk in Trixbox to connect to Lync:

    host=(the IP of the Mediation Server/Lync Front End)





    fromdomain=The IP of the trixbox (not sure if this what is supposed to be in there)







    Im hoping the issue will stand out to someone. 
    With the above trunk, Lync establishes a connection to the trixbox and I can call in both directions, although come to think I haven't tested to see if audio works in both directions, I ha jut go to the part where i could ring and answer. I had lync client and X-Lite client on PC so was content it worked. 
    I will test if audio works in both ways from lync to X-Lite client on 2 different PC's. If this fails then it may give me some common ground to work on.

    Sunday, September 4, 2011 4:19 PM
  • What codec is being offered by Trixbox ? Sometimes G711 is not being offered causing one way audio issue.

    The codec offered will be seen in the 200 OK (content portion) in the SipStack,S4 log from the Mediation Server.


    Wednesday, September 7, 2011 3:13 AM
  • Hi

    This is now working, but unfortunately I don't know why. I rebooted the trix box several times over the weekend and it just started working. I had been trying various bits and pieces, changing and deleting entries in the config files. So i am not sure what I have done, but it works now great. Apart from a 10 second delay before the recipient phone rings , all is well. Would like to know how to shorten this delay if anyone knows. Thanks everybody for your contributions.

    Friday, October 14, 2011 12:24 AM
  • I know this thread is very old but I am attempting to use Trix with Lync 2010 and wanted to get some advice on how to set up before running around in circles.  I originally set up Trix but I am definetly not the most comfortable making changes to it.  We have a working Trixbox now with Polycom phones and have a few Polycom Lync phones to try and get the setup working.  Any advice on the Lync or Trix side would be great.  Just for getting the trixbox talking with lync.


    Lead Pusher

    Tuesday, March 13, 2012 1:38 AM