TTY stands for Teletypewriter, a device that allows people who are deaf, hard of hearing, or have speech impairments to communicate over the phone. TTYs are used by typing messages on a keyboard, which are then sent as electrical signals over the phone line to another TTY. The other TTY converts the signals back into letters that are displayed on a screen. Some TTY models can also print a paper copy of the messages.
To make a TTY call to someone who doesn't have a TTY, you can dial 7-1-1 to reach the Relay service. The Relay service connects TTY users with people who use a phone by having a TTY relay service communication assistant (CA) relay the conversation. The CA speaks what the TTY user types and types what the phone user says. The Americans with Disabilities Act (ADA) requires nationwide relay services to be available 24/7 in every state and territory
