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What is TTY?

The telephone is a vital element in our daily living. We routinely use the phone to chat with friends, make dinner reservations, inquire about job openings, and even do our banking. For most of us, the telephone provides a convenience that we take for granted.

However, for the several million Deaf people in this country, the conveniences as well as life-saving capacities of the telephone have, until recent years, been inaccessible. Today, a Deaf or speech-impaired person can make telephone calls using a TeleTyprewriter (TTY). With the TTY, the conversation is typed rather than spoken and direct communication is possible with anyone who has a similar device. Calls placed to or from a non-TTY user can be placed through the Telecommunications Relay Service.

A growing number of government agencies and businesses are installing a TTY to provide direct phone communications o and for their Deaf employees and customers. Availability of this service is denoted with a β€œTTY” or β€œV/TTY” directly following the phone number. This service indicates to the public that they care about the needs of all of their customers.Β 


Telecommunications Relay Service provides voice telephone access to people who use TTYs. Specially trained agents complete calls and stay online to relay messages either by TTY, or verbally to hearing parties. This service is available 24 hours a day with no restrictions to the length or number of calls placed.Β 

Find your state’s toll-free telecommunications relay service number:Β Relay Service DirectoryΒ 


Some TTYs are now equipped with both Baudot and ASCII. Baudot is the communication code used by TTYs, and ASCII is the code used by computers. A TTY equipped with ASCII allows the user to call any computer that has a telecommunication set-up. If the TTY does not have ASCII, the computer must have a special modem to translate the Baudot code.

TTYs do not require special telephone equipment or installation. The telephone receiver, or handset, is put in the cradle of the acoustic coupler on the TTY before the conversation begins. The modem converts electric TTY impulses into acoustic signals and transmits those tones to the telephone receiver.Β 

Choosing the right TTY for your needs is important. We hope this information will be helpful in assisting with your decision. ADCO Hearing Products always has trained product specialists available to assist you in choosing the right product for you. Please contact us with any questions or concerns that you may have. We strive to maintain a wide selection of products that are competitively priced to meet your needs. If you find that our prices are higher than another reputable company, please let us know and we will gladly price-match.Β 

To help you further, please refer to the following glossary of commonly used terms:

  • TTY, TDD and TEXT TELEPHONE – All refer to the same device, a Teletypewriter, although TTY is the preferred acronym.
  • AUTO ID – Automatically transmits an audible tone to identify TTY calls. Especially helpful in emergency situations.
  • TURBO CODE – Allows typed information to transmit faster
  • MEMORY – Memory buffers allow information to be saved and retrieved as needed.
  • TTY ANNOUNCER – Pre-programmed voice announcement that identifies a TTY call.
  • VCO – Voice Carry Over, used in conjunction with the relay service where a user talks into a handset and reads incoming conversation.
  • HCO – Hearing Carry Over, used in conjunction with the relay service, the user listens to the other party and types their response using a TTY.