When the gateway in a Lync - SBC Edge - PBX topology fails, a Lync client will lose its connectivity with PSTN. The use of a back-up or fail-over gateway becomes highly desirable in order to maintain connectivity between Lync and PSTN.
This article describes the steps necessary to configure an additional SBC Edge (SBC) as a fail-over gateway along with the necessary Lync topology configuration bits. For the purpose of this article, it is assumed that PBX – SBC (Primary) – Microsoft Lync 2010 configuration is already in place with MTLS/SRTP as the SIP Transport as shown in the diagram below.
This is a two-part process; in the first part of the process, we use the Lync 2010 Setup Wizard on two different SBCs to point each of them at the same Lync Pool. In the second part, we do the complementary action on the Lync side by specifying both of the SBCs as PSTN Gateways using the Lync 2010 Topology Builder.
For this exercise, the following are the identities of the pool and SBC devices:
After successfully running the wizard, a primary SBC is configured for Lync 2010 Interoperability as shown below.
After successfully running the wizard, a secondary SBC is configured for Lync 2010 Interoperability as shown below.
To add the secondary SBC Node into the Lync Topology, please follow these steps:
To define the gateway:
Select Define New Gatewayto add the secondary SBC gateway as shown below.
To associate the gateway:
Click Add...to associate it with the Mediation Server as shown below.
Select Publish Topology...as shown below.
To configure voice routing:
Double-click the relevant policy_ in the list.
Double click the relevant PSTN usage record.
Double click on the Route entry.
Add the secondary SBC gateway into Associated Gateways list