DTMF issue when connecting to PSTN RRS feed

  • Question

  • I’m facing an identical issue on two separate installations of OCS. I have an OCS 2007 R2 with Exchange integration that is connected to either an AudioCodes or a CUCM 7 gateway via a mediation server.  


    The problem that I’m experiencing is related to DTMF, but only when connecting in via the PSTN network. In both scenarios (CUCM and AudioCodes) when I dial in to the Exchange UM or Dial-in conferencing facilities, DTMF does not work correctly. I did a couple of traces and it seems as if the all numbers send through via the DTMF is send through in duplicate. If for instance I want to enter 12345 the OCS / Exchange server is receiving 1122334455.


    The strange thing is that internally, everything works fine. A user connecting to the CUCM and AudioCodes directly, can successfully enter the require credentials when logging on.

    Both the CUCM and AudioCodes have been configured for RFC2833.

    Does anyone have any idea what might be causing this?

    Sunday, July 19, 2009 2:24 PM

All replies

  • Take a look at this blog article and see if it helps; could be applicable to at least the one CCM integration:

    Jeff Schertz, PointBridge | MVP | MCITP: Enterprise Messaging | MCTS: OCS
    Monday, July 20, 2009 11:12 AM
  • Casper,

    It seems like the inbound TEL - > IP numbers are being manipulated.  Couple of things to check:

    * In the Audiocodes Mediant navigate to the Protocol Configuration -> Manipulation Table -> Tel to IP
      * Make sure you are not addition anything in the 'Prefix to add'.  If there are digits in this box, those will be prepend to the inbound number before AudioCodes pass it to the destination i.e. UM or OCS.

    * Also make sure your Audiocodes is at correct firmware version that is certified to OCS R2; which is version M1000_SIP_F5.60A.012.005.cmp.

    * Also make sure if there is a Cisco IP load balanced in front of the OCS R2 Director, it is patched correctly - since there is a known issue with the Cisco LB

    * Get a protocol trace on the FE, Mediation, Access Edege and Director for S4, Inboundrouting, outboundrouting, SIP with ALL flags.



    Monday, July 20, 2009 9:04 PM
  • Hi Guys,

    Thanks for the reply. I reviewed the PointBridge Blog post and unfortunately this is only applicable for internal calls, which works fine. The issue still remains when connecting via a gateway device.

    On the AudioCodes side, I’m doing no manipulation on the AudioCodes at this moment in time. Everything is passed to the OCS server “as is”.

    My gut feeling is, that it has something to do with the PSTN Gateway devices, but as my GSM gateway has no DTMF related settings, I’m forced to try and get a resolution on my media gateways. Not sure if that is even possible....



    Tuesday, July 21, 2009 5:26 AM
  • Certainly the gateway is a good place to start. I have seen similar issues with Cisco gateways. I would follow james suggestion of checking your firmware version to begin with as it is highly probable it could be the issue.
    Friday, July 24, 2009 3:50 PM