Routes

Routes in Lync consist of a pattern to match and a list of trunks to use, which ultimately determines which gateway or SIP trunk is used to place a call. The patterns on routes again use regular expressions to search for a match against the E.164-formatted number after it has been processed by the dial plan. There are no translation rules on routes—the pattern is only evaluated to see whether a match exists. If the pattern matches, the route can be used and the call will be sent to one of the trunks listed on the route.

Each route is also associated with one or many PSTN usages. The fact that the associated PSTN usages are included in a voice policy is what allows a particular route to be used for a call. The specific pattern a route is searching for is typically described by the name of both the PSTN usage and the route.