In a previous post I discussed how the policies related to PSTN re-routing and bandwidth policy override worked. In this post I’ll use the same setup and describe how to configure voice routing to support PSTN re-rerouting. I will assume that the calling user is allowed PSTN re-routing by policy and that Alice has been configured with Line URI +4512345678 and Bob with Line URI +4587654321
PSTN re-routing is the ability of the Lync Server to re-route a Lync call via an external network in case bandwidth is restricted. The network is typically the PSTN, but could also be a private PBX infrastructure.
Lync re-routes the call to the Line URI of the called user. It bypass the normal Reverse Number Lookup (RNL), such that the call is not converted back to a Lync call.
The voice policy of the calling user and the normal voice routing configuration are also used for PSTN re-routing. Outbound Routing (OBR) will look to find a matching route (PSTN Usage and number pattern). In order to make sure PSTN re-routing can happen it is therefore necessary to ensure that voice routes are available for the DID range(s) used for Lync users and that PSTN gateways in all sites are listed in those voice routes.
For the setup above the following voice route would enable PSTN re-routing for users with PSTN usage “DK”:
OBR use the following logic when trying to route the call via PSTN re-routing:
Let’s try to summarize the different outcomes in the scenario where Alice calls Bob, bandwidth is restricted and Alice has been allowed PSTN re-routing: