PSTN Reroute

The capability to route calls between users in different offices even when the WAN is unavailable is referred to as PSTN reroute. As discussed previously in the “Voice Routing” section, the ability for PSTN reroute to function is based on whether it is enabled in the user’s voice policy, and whether a PSTN usage allows calls to the destination number.

When it’s enabled, if users in two sites cannot call each other because of a WAN outage, a PSTN call can be placed through a local media gateway, received by a media gateway at the remote site, and still delivered to the user. This happens automatically within the Lync client, and the end user sees a notification that the call is being rerouted and might take longer than usual to connect.