Access for 9-1-1 and Telephone Emergency Services

Recognizing TTY Calls/Treating Silent, Open Lines as Potential TTY Calls

All call takers must be able to recognize and handle TTY calls properly. There are three types of TTY calls a call taker may receive. Some TTYs emit a recorded spoken announcement to the call taker that a TTY call is being placed, such as "HEARING IMPAIRED CALLER. USE TTY." Other times, TTY callers may press TTY keys to emit audible tones and more quickly notify the call taker that a TTY call is being placed. Most often, however, a person using a TTY will make a call that is perceived by the call taker as a silent, open line call. This is because the caller's equipment does not recognize that the call has been answered until the call taker sends a TTY response.

The only way for PSAPs to properly identify all TTY calls is for call takers to recognize TTY tones and to query every silent, open line call with a TTY to determine if it is a TTY call after it has been queried by voice.