An assistive technology typically used by people who are deaf or cannot speak for purposes of communicating via the phone. TTYs typically have a keyboard and a two-line display with ringing function via flashing lights. TTYs allow users to type messages over the phone lines to other TTY users. Users can acoustically couple the TTY to the phone or the TTY can connect directly to an IP network via an FXS port. Also sometimes called a TDD, or Telecommunication Device for the Deaf.
a device that allows text communication over standard telephone equipment. Additional information.
Formerly TDD of TTY a text telephone is a telecommunications device used by those who cannot understand on the phone. A typewriter-like unit shows the conversation on a screen so that it can be read. A text telephone must "talk" with another text telephone or a computer.