ARCHIVED: What are TDDs and TTYs?

This content has been archived, and is no longer maintained by Indiana University. Information here may no longer be accurate, and links may no longer be available or reliable.

Telecommunications Devices for the Deaf (TDDs) and Teletypewriters (TTYs) are nearly interchangeable terms to describe the terminal devices used by deaf people for text communication over telephone lines.

TDD and TTY devices are usually the size of a small laptop with a keyboard and small screen, which typically only displays one line of text. Often, a small printer is attached to the devices for making transcripts of terminal sessions. As technology advances, TDDs and TTYs are being replaced by Internet services, such as email and instant messaging.