One way audio - Call Manager gateway FXS port-> OC ok but OC -> Call Manager gateway FXS port not RRS feed

  • Question

  • Hi, anyone had a similar issue, I need to do some digging into the SIP SDP but am posting in case someone has seen this and there is something obvious wrong.


    I have

    - OCS and OC (Of course)

    - Cisco Call Manager 5.1.3

    - Cisco 3640 running 12.4(10a) with analog phone conencted to FXS port


    When I make a call to or from the analog phone conencted to the Cisco gateway, I get one way audio from analog phone to OC client.


    I have other SIP trunks from Asterisk for example, and this problem does not occur with SIP clients connected to Asterisk, so something different is happening with the signalling from the mediation server to call manager than from asterisk to call manager


    The actual problem is clear, the cisco media gateway is not listening on the media port that the mediation server is sending the RTP to, I can see this when tracing the traffic and the gateway is sending back icmp unreachable.


    If I call a Cisco IP phone from OC it works fine, it's just the analog FXS port which fails, and only with media coming from OCS


    As I said before, this two way RTP flow works from Asterisk to Call Manager but not from OCS.



    Any ideas, any known bugs ?

    Thursday, November 22, 2007 3:45 AM

All replies

  • Hi,


    What protocol is your FXS gateway running? SIP? Do you have MTP's setup for your SIP trunk to OCS?





    Friday, December 28, 2007 3:45 AM

    Hi, yes sorry I didn't mention the gateway signalling protocol. When I had the problem I was running mgcp, as soon as i changed to SIP trunk to gateway, everything worked fine.



    Friday, December 28, 2007 3:49 AM
  • Hi Mark,


    Sounds like an MTP issue to me then since you said when you change to SIP it worked fine. When using MGCP the terminating SIP trunk from callmanager to OCS will need to terminate on to an MTP on Callmanager. Hardware IOS MTPS are best as the Callmanager software MTPS can cause issues with OCS integration.


    Hope this helps. 




    Wednesday, January 2, 2008 4:52 AM