FNZAK@WEIZMANN.BITNET.UUCP (04/28/87)
After discussing with Sarah Ferguson the topic of converting a terminal+modem
into a TDD-compatible machine, I decided that the information may be useful
if it is made more widely available.
TDD machines use a special modem standard (Weitbrecht) which is half duplex
and works at about 50 baud.
Some modem manufacturers manufacture modems which can work at either Bell 103
or Weitbrecht standards. The only case of which I remember is that Novation
once advertised a modem card which does the above. You may inquire there.
In addition, one of the TDD manufacturers (Krown Research) also manufactures
such a modem (if I remember correctly). However, it may be overpriced.
If you adopt the above approach, you need to replace the modem in your setup
by one of those modems.
The other approach is to exploit the fact that there are TDDs which work
at both Weitbrecht ("Baudot") and Bell 103 ("ASCII") standards. If you are
contemplating the conversion for the benefit of a particular deaf individual,
how about checking whether he/she is using such a TDD? If it is so, no
conversion work is needed by you.
While I am not familiar with TDDs issued by the phone companies, if I
remember correctly, they are required to be able to work at both standards.
Thus, the percentage of such TDDs among the deaf population is expected
to increase over time, eventually making the issue of converting a terminal+
modem into a TDD-compatible machine - a moot issue.