This question comes up again and again. It seems logical: why not use your computer and modem to communicate with TDDs? Trouble is, more often than not because of conflicting standards it won't work.
Most TDDs use a very old technology called Baudot (pronounced "baw DOUGH"). It has different character codes than computers and uses completely different audio tones to send signals through phone lines. Regular computer modems can't understand Baudot tones or codes, and most TDDs, especially older ones, can't understand the ASCII character codes and high speeds we use with our computers. It's a standoff.
Now, if you're lucky, your friend may have more recent, more deluxe TDDs that can communicate in ASCII as well as Baudot. If that's true, then you need to set your modem to 300 baud (the speed is important) and try 8 data bits, 1 stop bit, no parity and half--not full--duplex. You may have to try other parity settings (even or odd) to get this to work, depending on how your friend's TDD is set up.
If you friend does not have an ASCII-compatible TDD, there are a few alternatives:
1. Persuade your friend to purchase a new TDD.
2. Persuade your friend to get a computer with a modem and get on AOL or any other national bulletin board service like CompuServe, GENIE, and FIDO-net bulletin boards.
3. Buy a combination Baudot/ASCII modem.
That third option sounds good, but there's a big problem. Two problems, in fact. First, almost all of the combination Baudot/ASCII modems out there are not "Hayes compatible." That means they can't be used with standard programs (like the AOL software, or Microphone or Crosstalk) because they don't recognize standard commands to to do things like dial out. They usually come with their own special, limited-purpose software.
Problem number two: all of the combo modems, including the one that is Hayes-compatible (see below) will only go up to 300 baud in ASCII mode! Nobody in their right mind would ever try to use a 300 baud modem to log onto AOL or any other computer info service...it's about ten times too slow. So if you bought one of the Ultratec modems to talk to your friends with TDDs, you would STILL have to keep your regular high-speed modem for use with AOL. That's an expensive, complicated setup.
Bottom line: ask your friend if s/he has an ASCII-capable TDD. If s/he does, you can connect with her or him (with luck and some fiddling around). If not...consider the alternatives mentioned.
Sources for equipment and information:
Harris Communications
800-825-6758 (voice)
800-825-9187 (TDD)
612-946-0924 (fax)
Supplier of a wide variety of deaf-related products, including phone flashers, books, videotapes and the complete line of Ultratec TDDs. Ask for their catalog.
Ultratec
6442 Normandy Lane
Madison WI 53719
608-238-5400 (voice/TDD)
608-273-0707 (V/TDD)
The major source for TDDs in the U.S. Their Hayes-compatible ASCII/Baudot modem, the "Intellemodem," runs at 300 baud in ASCII and 45.5 baud in Baudot.
Phone-TTY Inc.
202 Lexington Avenue
Hackensack NJ 07601
201-489-7889 (voice)
201-489-7890 (TTY)
201-489-7891 (FAX)
201-489-3323 (CBB)
Manufactures the CM-4; also distributes other makes of modems, TDDs, signalling devices etc.
Krown Research Inc.
10371 West Jefferson Blvd.
Culver City CA 90232
213-839-0181 in California
800-833-4968 elsewhere
Manufactures the SM-85 modem and other TDD devices.
MicroFlip
11211 Petworth Lane
Glenn Dale, MD 20789
301-262-6020 (V/TDD)
Manufactures the MIC300i modem and the associated software for MS-DOS, called "FullTalk".