TDD

Definition:

Telecommunications Device for the Deaf. Used in 7‐1‐1 call services. 7‐1‐1 is assigned nationwide for access to Telecom

Relay Services (TRS). TRS allows persons with a hearing or speech disability to use the telephone. These consumers use

special telephone devices known as text telephone or a Telecommunications Device for the Deaf (TDD).

The sound provided to a caller to indicate the desired destination is unavailable. (60 IPM (interruptions per minute).)

An Alternate PSAP is designated to receive 9‐1‐1 calls if the call cannot be delivered to the primary PSAP.

The Zone Default number is like an MSC (Mobile Switching Center) default for GSM (Global System for Mobile Communication). Because there are...

The entity responsible for establishing and overseeing the functions necessary to accept 9‐1‐1 calls from carriers and deliver to PSAPs using...

Glossary of Terms