Telecommunications device for the deaf

Other names for the device include teletypewriter (TTY), textphone (common in Europe), and minicom (United Kingdom).

In addition, TDDs commonly have a small spool of paper on which text is also printed – old versions of the device had only a printer and no screen.

The text is transmitted live, via a telephone line, to a compatible device, i.e. one that uses a similar communication protocol.

The term TDD is sometimes discouraged because people who are deaf are increasingly using mainstream devices and technologies to carry out most of their communication.

Teletype Corporation, of Skokie, Illinois, made page printers for text, notably for news wire services and telegrams, but these used standards different from those for deaf communication, and although in quite widespread use, were technically incompatible.

When computers had keyboard input mechanisms and page printer output, before CRT terminals came into use, Teletypes were the most widely used devices.

In 1964, Marsters, Weitbrecht and Andrew Saks, an electrical engineer and grandson of the founder of the Saks Fifth Avenue department store chain, founded APCOM (Applied Communications Corp.), located in the San Francisco Bay area, to develop the acoustic coupler, or modem; their first product was named the PhoneType.

During the late 1960s, Paul Taylor combined Western Union Teletype machines with modems to create teletypewriters, known as TTYs.

In the early 1970s, these small successes in St. Louis evolved into the nation's first local telephone relay system for the deaf.

The battery-powered MCM was invented and designed by a deaf news anchor and interpreter, Kit Patrick Corson, in conjunction with Michael Cannon and physicist Art Ogawa.

After a year Micon took over the marketing of the MCM and subsequently concluded a deal with Pacific Bell (who coined the term "TDD") to purchase MCMs and rent them to deaf telephone subscribers for $30 per month.

However, the lack of true computer interface functionality spelled the demise of the original TTY and its clones.

During the mid-1970s, other so-called portable telephone devices were being cloned by other companies, and this was the time period when the term "TDD" began being used largely by those outside the deaf community.

In 2009, AT&T received the James C. Marsters Promotion Award from TDI (formerly Telecommunications for the Deaf, Inc.) for its efforts to increase accessibility to communication for people with disabilities.

[6] The award holds some irony; it was AT&T that, in the 1960s, resisted efforts to implement TTY technology, claiming it would damage its communication equipment.

In 1968, the Federal Communications Commission struck down AT&T's policy and forced it to offer TTY access to its network.

[8] The UltraTec company implements another protocol known as Enhanced TTY, which it calls "Turbo Code," in its products.

Turbo Code has some advantages over Baudot protocols, such as a higher data rate, full ASCII compliance, and full-duplex capability.

However, Turbo Code is proprietary, and UltraTec gives its specifications only to parties who are willing to license it, although some information concerning it is disclosed in US patent 5,432,837.

Other protocols used for text telephony are European Deaf Telephone (EDT) and dual-tone multi-frequency signaling (DTMF).

For those with hearing difficulties the telephone ring and conversation sound level can be amplified or pitch adjusted; ambient noise can also be filtered.

[clarification needed] A new development called the captioned telephone now uses voice recognition to assist the human operators.

Miniprint 425 TDD. The acoustic coupler on the top is for use with telephone handsets. The printer records the conversation. The specific GA and SK keys allow for speedier use of common abbreviations .
AT&T TDD 2700