What Does TTY Stand For?

By Contributor

Updated September 28, 2017

What Does TTY Stand For?
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A TTY allows deaf and hearing-impaired users to communicate over conventional telephone lines. Users of a TTY device type text into a specialized device, and this text gets to a TTY device on the other end.

What TTY Stands For

TTY stands for "text telephone" or "telephone typewriter."


TTY devices are sometimes called "telecommunications devices for the deaf," or TDDs.

Two-Way Communication

TTY devices require the user on the other end to also have a TTY device, unless a telphone relay service is used.

Telephone Relay Service

Telephone users with hearing must use the relay service if they do not have a TTY device themselves. An operator types the message and sends a text message to the TTY user. The operator speaks the text messages received from the TTY into her phone to allow the person with a standard telephone to hear the message.

TTY Phone Devices

Some TTY devices plug directly into the phone line, or in other instances, the user may have to place the phone receiver on the top of the device.