TechWhirl (TECHWR-L) is a resource for technical writing and technical communications professionals of all experience levels and in all industries to share their experiences and acquire information.
For two decades, technical communicators have turned to TechWhirl to ask and answer questions about the always-changing world of technical communications, such as tools, skills, career paths, methodologies, and emerging industries. The TechWhirl Archives and magazine, created for, by and about technical writers, offer a wealth of knowledge to everyone with an interest in any aspect of technical communications.
Subject:Re: Fax machines/modems and voice calls From:Fred M Jacobson <fred -at- BOOLE -dot- COM> Date:Tue, 22 Jun 1993 08:52:33 PDT
> I was looking at one pf thos [switches that distinguish fax calls from
> voice], but couldn't find any indication of how
> it handles computer calls, as distinguished from computer/faxcard calls.
> Know how it does on that score?
The handshake for fax requires the caller to send a tone, so it is easy for
a device (built into the fax receiver or added on) to distinguish a fax
caller from another. (They usually fool the human caller by sending a phony
[;-)] ring over the line while they listen for the tone. Sometimes it sounds
different enough so you can tell.) The protocol for data modems requires
the answering modem to send a tone (you've probably heard it), so the devices
need to get a responce from the (human) caller to identify the voice call
(I think). They use something like a recording asking the caller to press
a key on her phone's keypad.
-Fred
--
INTERNET: fred -at- boole -dot- com PHONE: (408) 524-3292 FAX: (408) 730-0558
USPS: Fred Jacobson / Boole & Babbage / 510 Oakmead Pkwy / Sunnyvale CA 94086
