ESRN
Emergency Services Routing Number. This is a unique number assigned to an emergency call in voice peering for routing the call to the correct PSAP...
Definition:
1. Emergency Service Number A three-digit number that is assigned to the caller's telephone number in the tandem office translations. The emergency service number routes the call to the proper PSAP. PSAPs also receive a display of the ESN information. The display shows which police, fire, and ambulance agency serve the telephone number calling 9-1-1.