Configuring Inter-Trunk Routing

Inter-trunk routing is a feature new to Lync Server 2013 that allows calls to route through Lync. This enables administrators to place Lync “in front of” a PBX or another system, and still be able to route calls to the downstream, legacy PBX.

Inter-trunk routing is configured by assigning a collection of PSTN usages to a specific trunk configuration. As calls come in to Lync through that trunk, they will be evaluated against the PSTN usage list and potentially routed out another trunk. From an outbound routing perspective, treat the trunk the call was received on as the Lync voice user. Similar to how a user’s voice policy processes PSTN usages to select an outbound route, the PSTN usages assigned to that trunk will be processed and look for a matching route.