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What exactly is a TTY, TDD and/or Text Telephone?... is there a difference?

With all the acronyms and other confusing lingo, people find it hard to understand what a TTY or TDD or text telephone is and what it actually does. Of course, nobody is going to buy something they don't understand, so let us explain. All these different names mean the same thing: TTY stands for teletypewriter, TDD stands for Telecommunication Devices for the Deaf and Text telephone means a phone that is enabled to send text over phone lines. All these terms are referring to the same device.

So how does a TTY / TDD / Text Telphone work?

This device or phone, when hooked up to a phone or analog jack, allows for the typing of messages back and forth between text telephones. Anybody can call in to a TTY phone (presumably to a hard of hearing or deaf person) from a relay service, also known as Telecommunications Relay Service or TRS (people love making up acronyms). Under Title IV of the Americans with Disabilities Act, this service must be offered free of charge by every state (just press 7-1-1 to get into touch with a representative from your state relay center).

The Text telephone user can call in to the relay service and give the service representative a phone number to call to facilitate the relay. The TTY user can type in the message which the relay rep will verbally relay to the other person. The other person will verbally speak his message and the relay representative will type it into the Text telephone. Also, a non-TTY user can facilitate a call to the relay service (also by calling 7-1-1) so he or she can communicate with a TTY user. This service is available 24 hours a day.

What is VCO?

Some Text Telephones offer VCO (yet another acronym) which stands for Voice carry over. This feature allows people who are hard of hearing but not speaking to communicate verbally but get typed communication relayed from the relay representative to the TTY phone.

What is HCO?

Some text telephones offer HCO (another one?) which stands for hearing carry over. This feature allows people who hear clearly but have difficulty speaking on the phone to communicate through the relay representative by typing and listening to the other person regularly. So the relay representative will verbally relay your typed message while you listen to the person’s responses directly.

Federal law believes people with these types of disabilities deserve to communicate as effectively as everyone else, so we hope this information will help people understand and use these helpful services.

» Click here or more information about Relay Services

» Contact the FCC directly

» Click here to buy a TTY Phone

Some other common questions:

Is my cellular or cordless phone TTY compatible?

Please contact the manufacturer of the product you are looking to purchase to make absolutely sure your cellular or cordless phone is compatible with product your interested in:

Krown Manufacturing, Inc.
12082 Western Avenue
Garden Grove, CA 92841-2913
(800) 874-3005 voice
(800) 772-2889 TTY
(714) 897-4703 fax

Ameriphone, Inc.
3408 Indale Road
Fort Worth, TX 76116
(817) 738-2485 voice
(817) 738-8993 TTY
(817) 738-1970 fax

Can my computer communicate with a TTY directly?

Text telephone communication is done through a different type of Data transmission code than regular computers called Baudot, which is incompatible with ASCII (American Standard Code for Information Interchange), which is the worldwide computer standard code. A Baudot/ASCII modem, or TTY modem, is necessary to make your computer act like a TTY. This 300 baud modem is more expensive than regular data modems and can’t be used as a replacement for a data modem. You must have two modems for separate computer activities (if there is a modem out there that does both, please let us know).

Below is the most promising hardware and software provider we can find for this need:

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