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TDD (Telecommunications Device for the Deaf)
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Telecommunications Device for the Deaf (TDD)
The following is a definition of a TTY/TDD:
- A Telecommunications Display Device TDD, also known as a text telephone or TTY, is a telephone equipped with a keyboard and a display for people who are hearing- or speech-impaired.
- A TDD allows individuals to send and receive typed messages using its keyboard. Both home and public telephones can be equipped with a TDD.
History
The term TTY derives from "Teletype", which is a registered trademark of the Teletype Corporation. Like the word "aspirin", which was originally a trademark, the term "teletype" has become almost generic.
TDD, a later term, stands for "Telecommunications Device for the Deaf". Many people use the two terms interchangeably, while others use TTY for mechanical teleprinters and TDD for the modern electronic gadgets which perform the same function in a fraction of the size and weight. More recently, the Federal Communications Commission has come up with yet another term for the same thing. In one of their recent orders, they call it a "text telephone".
The TTY was first developed by Robert Weitbrecht, a deaf physicist. He was also a ham, and was familiar with the way hams use teleprinters to communicate over the air. He realized that these machines, which were becoming available in large numbers from military and telephone company surplus, could be used by deaf people to "talk" over the phone. He developed and patented a modem which, when coupled to a teleprinter, allowed them to do just that. The technology is very similar to that still used by hams: it uses Frequency Shift Keying (FSK) and a single tone pair, so that only communication can only take place in one direction a time.
TDD Technology
TDD devices can be used as stand-alone phones or can also be addressed using automatic phone messaging systems such as Voice broadcasting technology. Both voice and text messages can be broadcast during an emergency or community alert scenario [1].
Related Technology
- IVR Interactive Voice Response
