Glossary of Terms

Understand basic Public Safety definitions and terms.

Source Systems

Definition:

A telephone company’s customer records database that contains all telephone subscriber records.

ESS

Electronic Switching System - Computerized switching of telephone calls used by the telephone company.

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ICO

Independent Telephone Company. Pre‐divestiture term referring to any local telephone service provider that was not part of American Telephone and...

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Manual Transfer

A feature that enables the PSAP attendant to transfer incoming 9‐1‐1 calls by manually obtaining dial tone through use of the telephone switch or...

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DMS

Data Management System - A data base managed by the telephone company which includes ANI and ALI information.

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