ESN
1. Emergency Service Number A three-digit number that is assigned to the caller's telephone number in the tandem office translations. The emergency...
Definition:
Emergency Service Zone. An area in which all 9‐1‐1 calls are routed to a specific PSAP and in which all residents are
served by the same responding agencies. Each ESZ has its own administrative ESN (a 15‐digit number consisting of a 9‐
digit PSAP ID and a 5=digit PSAP ESN).