Changing SIP Transport from MTLS - SRTP to TCP - RTP

This article describes the steps necessary to modify the Sonus SBC 1000/2000 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 – Sonus SBC 1000/2000 – Microsoft Lync 2010 configuration is in place already with MTLS/SRTP as SIP Transport. 

The process requires changes on both the Sonus SBC 1000/2000 and on the Lync Server. The six steps to accomplish the change are:

1. Edit the appropriate Signal Group on the Sonus SBC 1000/2000.
2. Edit the appropriate Media List on the Sonus SBC 1000/2000.
3. Edit the appropriate SIP Server Table on the Sonus SBC 1000/2000.
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

Topology After

Sonus SBC 1000/2000 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 Group Before

SIP Signaling Group After

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 Crypto Profile ID value to None as shown below.

Media List Before

Media List After

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 Before

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 Sonus SBC 1000/2000 entry).
4. Right-click the relevant Sonus SBC 1000/2000.
5. Select Edit Properties...
6. Change the Listening Port for IP/PSTN gateway to 5068, as shown below.
7. Change the SIP Transport Protocol to TCP, as shown below.

8. Click OK.

   PSTN Gateway Properties Change

   

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