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This section of the Extended Microsoft UC Features Quick Start Guide describes the configuration of Microsoft Office Communications Server to use a VX node as a voice gateway.

Configuring OCS to Use VX as a Voice Gateway

After VX is added as an OCS Gateway, the OCS configuration must be changed to employ VX. Use the steps in this section to install a VX as an OCS Gateway.

To Configure OCS to use VX as Voice Gateway

  1. In the Microsoft Office Communications Server application, right-click Forest and then select Properties > Voice Properties.

  2. Select the Routes Tab, select the VX gateway and click Edit.

  3. In the Edit Route dialog, in the Gateways section, click the Add button.

  4. Select the VX gateway address from the drop down list and click OK.

  5. Confirm the address and click OK.

  6. Ensure other undesired gateways are removed.

Edge Server Configuration

If an edge server is installed, the VX must be added as a server with authorization to connect.

To Configure an Edge Server to Work with VX

  • On the Edge Server, set VX as an Internal Server using the server snap-in:
  • Or re-run the Edge Server wizard on the Front End and enter VX as an Authorized Internal Server.

To Configure VX to Work with an Edge Server

  1. Create a SIP Inbound Call Route for the connection to the edge server.
  2. In the Address/FQDN field of the SIP Inbound Call Route, add the fully qualified domain name of the edge server.

    Always use FQDNs for VX and OCS host addresses.

    Configure the FQDN of all Front-Ends into the SIP Inbound Table

  3. If the Enterprise OCS installation has a separate pool and front end (FE), both should be entered as SIP Inbound Call Routes.

To Configure VX to Communicate with OCS

  1. Edit the TrunkGroup view.

  2. Edit the Call Route view.

    The SIP domain in the Output Translation Rule, ( in the example above) is required.

    The SIP domain in the Output Translaton Rule must match the SIP domain from the Communicator sign-in screen.

  3. Ensure the OCS-Gateway configurations are correct for your installation.

  4. Ensure the Chassis (STIX TDM) Card \ Payload Feature is set for MSRTA or G.722.1.

    OCS expects a calling number.  Use the Calling Number translation to supply a calling number if none is present.

    If you attempt to send a SIP call to OCS/MOC without the STIX TDM loop, the user=phone will not be added unless the call plan/type is set to IDSN/National. Without user=phone, OCS will presume the TO URI is a SIP URI and not a telephone URI and it will fail to find the user. As noted earlier in this document, SIP to MOC calls are not supported without the TDM loop.

Secure Real-time Transport Protocol (SRTP)

VX is required to have a Security Accelerator Card installed in order to support SRTP connections. Before attempting to enable SRTP, you must verify that a Security Accelerator Card is installed.

To Confirm the VX has a Security Accelerator Card installed

  • In the VX CLI, use the sho card all command to list all installed cards, as shown below:
    extucdemo# sho card all
    Slot  Enabled State       In service Type                 Source clock state Number of DSP
    ===== ======= =========== ========== ==================== ================== =============
    1:2   true    active      true       STIX-4T1E1/DSP       PSTN Port 1        188
    1:15  true    active      true       Virtual              N/A                66
    N/A   true    active      true       Security Card        N/A
    The last line of this example output confirms there is a security card installed on this VX node.

If your VX configuration does not already contain a Crypto Class, you must add one.

To Add a Crypto Class

  1. In the VXbuilder Settings Tree, navigate to tree-root > Telephony > Media Crypto Classes.
  2. In the right panel, right-click anywhere and choose Insert to create a Media Crypto Class Table.
  3. In the Settings Tree, expand the Media Crypto Classes element and select the new Media Crypto Class Table.
  4. Double click the Media Crypto Class entry and

    There should only be the listed crypto suite shown above. No other crypto suites can be in the class.

Finally, adjust the settings of the inbound Trunk Groups for OCS.

To Configure Trunk Groups to Use SRTP

  1. In the VXbuilder Settings Tree, navigate to tree-root > Telephony > Trunk Groups
  2. Select the Trunk Group for the OCS server, and in the General tab, set the following fields:
    • In the Media Handing field, select Terminate SRTP Only.
    • Enable the Optional SRTP option.
    • In the Media Crypto Class field, set the class to #1 (default class).

Verifying MRAS Connectivity

After you have configured VX to communicate with OCS, you may wish to verify the MRAS to Edge Server connectivity from VX using the Command Line Interface.

To Verify MRAS Connectivity

  • In the VX CLI, use the sho mras to verify connectivity, as shown below.
    fmt-shout> en
    Password: ********
    fmt-shout# sho mras
    Media Relay Authentication Information
    MRA Server      :
    MRA Server IP   :
    MRA Port        : 5062
    MRA Server GRUU :;gruu;opaque=srvr:MRAS:hhj34m9
    VX GRUU         :;gruu;opaque=srvr:Gateway:baKhuVg
        Password: YoawWVWC0LCauPPSch/h3lEe5UI=
        Expiration Time : 480 mins
        Turn Server FQDN    :
        Turn Server IP      :
        TCP Port        : 443
        UDP Port        : 3478
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