Glossary of Terms

Understand basic Public Safety definitions and terms.

ESN

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.

2. Electronic Serial Number. The unique number assigned to a wireless phone by the manufacturer. According to the FCC,
the ESN is fixed and unchangeable.

Admin ESN

Administrative Emergency Service Number. An Admin ESN is a three‐ to five‐digit alphanumeric code that represents an Emergency Service Zone (ESZ). It...

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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...

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Overlap ESN

Overlap Emergency Service Number. ESN that is used for MSAG ranges in counties that border E9‐1‐1 counties and are provided dial tone by an end...

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ESCO

Emergency Service Central Office Number. The information delivered to the PSAP when there is an ANI failure between the end office and the 9‐1‐1...

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