Emergency Service Network Element. An entity in the emergency services network which serves as the point of interface
to an MSC. Also called a Selective Router or E9‐1‐1 Tandem. A feature in which 9‐1‐1 calls from a central office area that
is served by more than one PSAP are electronically routed to the proper PSAP. This is accomplished by the combination
of the routing ESN and the customer location information.