TTYs for the deaf

From: Fred Cisin <>
Date: Sat Dec 11 13:00:29 2004

On Sat, 11 Dec 2004, Michael Sokolov wrote:
> Hello folks,
> I have a question about those TTYs that the deaf use. Are they real
> Teletypes, like ASR33 and friends, or not? I guess probably not, because
> it would be so super-cool if they were that it's probably too good to
> be true, but I thought I would ask anyway. So what are they? Are they
> normal ASCII terminals with standard modems built in, or something
> entirely different?

They ARE Baudot (well, actually Murray) code devices.
SOME of the newest ones ALSO support ASCII.
The communications protocol is CCITT .18? (sorry, can't remember for
SOME (few) of the newest ones ALSO support Bell 103, Bell 202, 212, or
even v.90.

Most of the people using them do not understand the difference between
"code" and "communications protocol". Therefore, you will run into a lot
of confusion about "ASCII is a higher speed than Baudot", etc.

> Can one pretend to be deaf, go to some social service
> or whatever agency asking to use a deaf TTY, and dial into a timesharing
> host or BBS with it?
If you can prove a significant hearing impairment (they sometimes want an
audiogram, and an audiologists signature), you can get a long term free
loan of one. For a long time, there has been a tiny surcharge on all
phone service to pay for those programs.
Any large bank of payphones is SUPPOSED to include at least one - try your
nearest large airport.
They often show up at flea markets (often borrowed ones that weren't
There is also software available to emulate one with certain "voice"

> It also seems like there are two kinds of deaf devices, TTY and TDD.
> What's the difference?
"politically correct" name change.
"Teletype" v "Telecommunications Device for the Deaf" NO difference.

Grumpy Ol' Fred
Received on Sat Dec 11 2004 - 13:00:29 GMT

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