This article describes the steps necessary to modify the SBC Edge (SBC) configuration such that the SIP Transport is changed from TLS/SRTP (MTLS/SRTP) to TCP/RTP.

For the purposes of this article it is assumed that PBX – SBC – Microsoft Lync 2010 configuration is in place already with MTLS/SRTP as SIP Transport. 

The process requires changes on both the SBC and on the Lync Server. The six steps to accomplish the change are:

  1. Edit the appropriate Signal Group on the SBC.
  2. Edit the appropriate Media List on the SBC.
  3. Edit the appropriate SIP Server Table on the SBC.
  4. Edit the port and protocol settings on the Lync Server.
  5. Publish the altered topology
  6. Stop/Restart the Lync Mediation Server service.

Topology Before

PBX – SBC – Microsoft Lync 2010 configuration in place with MTLS/SRTP as SIP Transport

Topology After

PBX – SBC – Microsoft Lync 2010 configuration in place with TCP/RTP as SIP Transport

SBC Configuration Changes

SIP Signaling Group

  1. In the WebUI, click the Settings tab.
  2. In the left navigation pane, go to Signaling Groups > (relevant SIP Signaling Group).
  3. Change the Listening Ports configuration to 5068, as shown below.

  4. Change the TLS Profile ID to N/A.

SIP Signaling Listen Port

Media List

  1. In the WebUI, click the Settings tab.

  2. In the left navigation pane, go to Media > Media List > (relevant media list entry).

    This is the Media List specified in the SIP Signaling Group above.

  3. Change the SDES-SRTP Profile to None as shown below.

Media List Before

 

SIP Server Table

  1. In the WebUI, click the Settings tab.
  2. In the left navigation pane, go to SIP > SIP Server Tables >(relevant SIP Server Table Entry).
  3. Change the Port value to 5068, as shown below.

  4. Change the Protocol value to TCP, as shown below.

SIP Server Table After

Lync Changes (Topology Builder)

PSTN Gateway Properties Change

  1. Log into the Lync front end server PC.
  2. Launch the Lync Server 2010 Topology Builder.
  3. In the Navigation Tree, go to Branch Sites > PSTN gateways > (relevant SBC entry).
  4. Right-click the relevant SBC.
  5. Select Edit Properties...
  6. Change the Listening Port for IP/PSTN gateway to 5068.
  7. Change the SIP Transport Protocol to TCP.

  8. Click OK.

Publish Topology

To publish the topology:

  1. In the Topology Builder navigation tree, right-click Lync Server 2010.

  2. Select Publish Topology....

    Publish Topology

Lync Mediation Server Service Restart

  1. Launch the Lync Server 2010 Configurationpage
    1. In your brorwser, go to (the FQDN of the front end pool//cscp).
  2. Select the *Mediation Server in the Service list.
  3. Select Stop service from the Action drop-down list, as shown below.

  4. Select Start service from the Actiondrop-down list, as shown below.

    Lync Mediation Server Service Restart