TTY and TTY Relay Services

The invention of the telephone in the late 1800’s was heralded by most people.  However, people who are deaf or hard of hearing had difficulty or could not use the telephone at all.  For generations, deaf and hard of hearing people had to depend on hearing family members, friends, and neighbors to make telephone calls – to their doctors, children’s schools, and other necessary contacts.

Robert Weitbrecht, a deaf scientist, developed the teletypewriter (TTY) in the 1960s.  With the invention of the acoustic coupler (which holds the telephone handset receiver) and the distribution of recycled teletype machines, deaf and hard of hearing people were able to call each other directly using these devices.  In the late 1970’s and through the 1980’s, much smaller and compact versions of the TTY were manufactured, marketed, and made available through state TTY equipment distribution programs.

Calls between TTYs were terrific, but most people had telephones.  To provide greater access, TTY relay services began, first as volunteer programs with limited hours and areas, connecting deaf and hard of hearing TTY users with people who used telephones.  The TTY relay service communication assistant (CA) connects TTY relay calls with people who communicate by telephone.  The CA converts voice-to-text and text-to-voice communication.  The text is displayed on the user’s TTY.  Because communication using a TTY could flow only in one direction at a time, TTY etiquette was developed.  People who communicate using a TTY or TTY relay service, signal conversation turn-taking by saying or typing “go ahead” (GA) and signal the end of a conversation by saying or typing “stop keying” (SK).

With TTY relay services, deaf and hard of hearing people could finally call their hearing family members and friends, make their own appointments, order pizza, and make other calls on their own.  California became the first state, in 1987, to mandate and establish a state Telecommunications Relay Program.  Other states established their own state relay services and a patchwork of relay services emerged across the country.  In 1990, Title IV of the Americans with Disabilities Act (ADA) mandated nationwide relay services, to be available 24/7 in every state and territory.  More than 100 years after the invention of the telephone, deaf and hard of hearing people could finally make a telephone call to anyone.

Today, TTY relay services, the original and now “traditional” relay service, can be reached by anyone by dialing 711 from a telephone or TTY.  The 711 dialing feature is now available nationwide to access non-Internet-based relay services such as TTY relay services, speech-to-speech (STS) relay services, and voice carry over (VCO) TTY, and hearing carry over (HCO) TTY relay services.  For more information about 711, see

Many TTY users have migrated to other forms of communication to access the telephone network, using newer technologies and relay services, including Internet-based relay services.

TTYs, however, are still used by many people who are deaf or hard of hearing; particularly by people who do not have access to available, affordable broadband and Internet access.  TTYs also continue to play an important role by providing direct access to 9-1-1 emergency services.Related IssueAccess to 9-1-1 Emergency Services