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TTY/TDD General Information


What is a TTY?

TTY stands for TeleTYpewriter (previously known as a TDD, a Telecommunications Device for the Deaf or text telephone).  The TTY consists of a keyboard and a display screen.  A TTY user types letters that are converted into electrical signals and travel over regular telephone lines (either directly or by the user having placed the telephone handset on the TTY itself) to another TTY, where they appear on a display screen and/or a paper print-out.  The TTY has four million users nationwide (three million are deaf or hard of hearing, and one million have severe speech disabilities).

What are telephone relay services?

Telephone relay services are the answer to the following questions:

  • How can a deaf or speech-impaired individual communicate with one another or with others who have no TTY?
  • How can someone communicate on a telephone with someone who can only communicate with a TTY?
  • How can someone speak on the phone with someone who has a speech disability?

Below is a description of the California Relay Service, used to facilitate communication between standard telephone and TTY users, and the Speech-to-Speech service, as well as used to facilitate telephone conversations with those who have speech disabilities.

California Relay Service

The California Relay Service is a telecommunications relay service that provides full telephone accessibility with TTY users.  Specially trained Communication Assistants (CAs) complete all calls and stay on-line to relay messages electronically by typing on a TTY or by voicing information to hearing parties. The Relay Service is available 24 hours a day, 365 days a year, with no restrictions on the length or number of calls placed. There is no additional cost for the service; calls are billed at regular rates. This valuable tool gives individuals who have TTYs and those who are not able to communicate effectively via telephone.

The state of California began using a relay service before the signing of the Americans with Disabilities Act (ADA) into law on July 26, 1990.  Title IV of the ADA requires all telecommunications common carriers (telephone companies) to provide, or contract to provide, full interstate Telecommunications Relay Services (TRS).  Currently, Sprint has the contract to provide these services.

How does the California Relay Service work? CRS enables hearing people using a standard telephone to communicate with people who are deaf, deaf-blind, hard-of-hearing, or speech disabled, and use a TTY or a specially equipped personal computer, and vice versa. A person who is deaf-blind may use either a TTY (often with a larger visual display) or a TeleBraille device (with refreshable Braille display). A person who is speech-disabled types his/her conversation for the Communication Assistant to read to the standard telephone user, but can listen to the person being called with Hearing Carryover service (also known as voice carryover). These conversations take place in real time. By law, all calls are handled in strict confidence. 

How to make a California Relay Service call to someone with a TTY

  • Call the Relay Service by dialing 711.  Tell the CA the number you wish to call and the person to whom you wish to speak.
  • Wait briefly while the CA dials the TTY user.  After making the connection, the CA will tell the TTY user that this is a relay call.
  • As with any telephone call, you and the TTY user take turns.  The CA will voice the TTY user’s words to you, and will type your words on the TTY for the TTY user.
  • It is impolite to interrupt the other person while talking via TTY.  It is respectful to be brief and to the point, taking breaks to give the other person a chance to respond.
  • During the conversation, each time you finish with your turn and wish to hear from the other person, say “go ahead” or “GA” (like saying “over” in radio talk).
  • Deaf TTY users may not have a broad range of English skills and for many, English is their second language.  Some may use what seem to be awkward phrases, misspelled words, or may communicate thoughts and ideas without using Standard English grammar, syntax, or sentence structure.  Take care to be respectful and try to avoid jargon and use language that the caller will be able to understand, depen-ding on his or her facility with English.
  • The CA will relay what you say to the TTY user verbatim.  Be sure to talk directly to your caller, not to the CA.  For example, say, “How are you today?” rather than “Ask him how he is today.”
  • At the end of the conversation, you or the TTY user say “GA to SK” (TTY shorthand for “stop keying”).  If also finished, the other person will say “SK” and you both can hang up.
  • A Relay Service call will likely take a bit longer than a standard telephone call.  Be sure to set aside sufficient time for your call.
  • Calls with TeleBraille users may take longer than the average Relay Service call.  The TeleBraille unit works like a TTY but uses a Braille display that takes longer to read than a visual output TTY screen.  Be patient if the person you are calling takes a little while to respond.

Use one of the California Relay Service telephone numbers

711 or 1-877-735-2929  TTY/TDD calls
1-888-877-5379 Voice
1-888-877-5381 Spanish
1800-676-3777 Customer Service (Voice or TTY)

Speech-to-Speech Service

Some individuals with speech-related disabilities may have difficulty being understood in standard telephone conversations, particularly if the callers are not well known to each other.  Speech-to-Speech users may have Parkinson’s disease, cerebral palsy, multiple sclerosis, ALS, muscular dystrophy, or are people who stutter or have had a laryngectomy.  Speech-to-Speech may also be useful for those who use speech synthesizers.  This Speech-to-Speech service provides an intermediary “communication assistant” to facilitate effective telephone conversations.

How does the Speech-to-Speech Service work?

The STS access number for California is 711. 

Anyone may access this service, either the individual with a speech disability or someone who would like to telephone a person with a speech disability.  Either party can dial toll-free 24 hours a day to reach a trained operator who is familiar with many speech patterns and has acute listening skills.  This STS Communication Assistant (CA) then completes the connection by calling the other individual.  The CA is there to listen to messages from the person with a speech disability, and re-voice that message to the other party to the conversation.  In this way, telephone communication will be clear and accessible to both individuals.

What is Voice Carry Over (VCO)

People who can speak clearly but have difficulty hearing can also place or receive calls through the relay service. Many people in this category are senior citizens or others who become deaf later in life. This type of relay call is Voice Carry Over (VCO) because the hard of hearing person's voice is "carried over" to the other party. In this category, no typing is required, except by a communications assistant. A communications assistant types everything that the other person says and the words appear as text on the VCO user’s TTY or on a voice carry over phone.

What is Hearing Carry Over (HCO)

People who can hear clearly but have difficulty speaking on the phone can also place or receive calls using the relay service. This type of relay call is Hearing Carry Over (HCO) because the person with a speech disability is able to "hear" the other party's voice. HCO users can type what they want to say using a TTY. As is the case with other relay service calls, communications assistant then reads their words to the person they called.

Based on original documents, courtesy King County (Washington) Office of Civil Rights and City of San Francisco's Mayor's Office.