Thread Subject: TTY 255 Guidelines and 508 Standards ... for 11.27Telecomm Subcomm. Discussion

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From: Brooner Mary-AMB004
Date: Mon, Nov 27 2006 9:20 AM

TO: TEITAC Telecomm Subcommittee Members
>From : Mary Brooner
RE: 11.27.06 Conference call meeting - Topic is TTY

Below are the text segments relating to TTY for discussion today.


Section 255 Guidelines:

5.3.4.6 (C-6). Text Telephone Connectability.

Guideline: Where readily achievable, products which provide a
function allowing voice communication and which do not themselves
provide a TTY functionality shall provide a standard non-acoustic
connection point for TTYs. It shall also be possible for the user to
easily turn any acoustic pickup on the product on and off to allow the
user who can talk to intermix speech (live microphone) with text
telephone use.

Rationale: Individuals who use text telephones (TTYs) to
communicate using text-over-telephones must have some non-acoustic way
to connect TTYs to telephones to get clear TTY connections. Acoustic
coupling is subject to interference from ambient noise, as many handsets
do not provide an adequate seal with TTYs. Therefore, alternate
(non-acoustic) connections are needed. Control of the microphone is
needed for situations such as pay-phone usage, where ambient noise
picked up by the mouthpiece often garbles the signal (user needs to be
able to mute the handset microphone). Some users of TTYs cannot hear and
use the TTY to receive communication but can talk and use speech for
outgoing communication. The microphone on/off switch on the telephone
should therefore be easy to flip back and forth or have a push-to-talk
mode available.


5.3.4.7 (C-7). Text Telephone Signal Compatibility.


Guideline: Where readily achievable, products providing voice
communication functionality shall be able to support use of all
cross-manufacturer non-proprietary standard signals used by
telecommunication devices designed for use by or with people who are
deaf, hard of hearing or have speech impairments.

Rationale: Some telecommunication systems, which have been
developed and released, compress the audio signal in such a manner that
standard signals used by TTYs are distorted or attenuated, preventing
successful TTY communication over the systems.

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