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CSTA Gateway Connections to OCS RRS feed

  • Question

  • We have had stable integration between our UDP SIP PBX and UM on Exchange 2007 for some time but now need to look at full OCS integration (using remote call control).

     

    My understanding is the the mediation server will provide a gateway for TLS > TCP SIP flow (assuming the next hop only supports TCP), but with Remote Call Control enabled on Office Communicator and the mediation server set as the default (only) route for all calls, I see no traffic hitting the mediation server. Worse still, Communicator has the error "The call control server may be temporarily unavailable.........". There is currently no CSTA gateway installed in this scenario.

     

    My questions:

     

    1.) Is the CSTA gateway expected to have registered it's abilities to OCS via the mediation server for RCC to be enabled, or should the mediation server just pass CSTA messages embeded in SIP to the IP address it believes the CSTA gateway to be at without any other form of a tie in?

     

    2.) If the latter, is the Communicator error likely unrelated to the lack of CSTA gateway - this error disappears when Enterprise voice is enabled and Communicator can happily connect to UM for voicemail etc.

     

    Many thanks if you are able to provide some pointers.

     

     

    Friday, October 31, 2008 5:48 PM

Answers

  • In an RCC-only deployment (no Enterprise Voice functionality) the Mediation Server role is neither required nor used.  In a dual-mode deployment you'll still need the Mediation server for EV traffic but any RCC signalling moves between OCS and the phone system's own gateway (e.g. the CUPS server in a Cisco deployment).

     

    Saturday, November 1, 2008 2:06 PM
    Moderator

All replies

  • In an RCC-only deployment (no Enterprise Voice functionality) the Mediation Server role is neither required nor used.  In a dual-mode deployment you'll still need the Mediation server for EV traffic but any RCC signalling moves between OCS and the phone system's own gateway (e.g. the CUPS server in a Cisco deployment).

     

    Saturday, November 1, 2008 2:06 PM
    Moderator
  • Thanks for the fast reply Jeff. Just to clarify my (lack of!) understanding:

     

    1.) So with RCC only enabled, the key settings are the 'Server' and Line URIs in the user settings. If my CSTA gateway is on a machine with FQDN csta.mydomain.local then the server could read "sip: anythingIlike@csta.mydomain.local" ???

     

    2.) Is there any way to set the type of traffic flowing between OSC and the csta gateway? ie. I'd prefer in the short term if this was plain TCP rather than TLS / MTLS.

     

    3.) Nothing in the Location based routes or static routes affect RCC traffic?

     

    4.) Am I missing some MS documentation that would have explained all this? I have all the deployment guides, OCS admin guide and VoIP guide but they appear to be short on specific detail.

     

    Thanks again Jeff.

    Sunday, November 2, 2008 1:08 PM
  •  

    I've been able to answer my own questions.

     

    1.) Basically yes. I've set my server URI to sip:mycstagateway@mydomain

     

    2 & 3.) A (static?) route is needed for the server URI the same as it would be for any other. This route can be set to TCP or TLS.

     

    4.) Would be nice to have this documented somewhere.

     

    I am now seeing the initial INVITE with RequestSystemStatus and a SUBSCRIBE for presence on the csta box.

     

    Thanks for the pointers Jeff, they paved the way.

    Sunday, November 2, 2008 3:11 PM