Path: utzoo!mnetor!uunet!husc6!bu-cs!polygen!pablo
From: pablo@polygen.uucp (Pablo Halpern)
Newsgroups: comp.sys.mac
Subject: Re: Modems/Emulators recognizing Call Waiting?
Message-ID: <128@polygen.UUCP>
Date: 16 Mar 88 17:28:16 GMT
References: <21864@bbn.COM>
Organization: Polygen Corporation, Waltham, MA
Lines: 28

In article <4201@husc6.harvard.edu> hellerst@husc8.UUCP (Joe Hellerstein) writes:
>Is there such a thing as a modem, and/or terminal emulation software, that could
>recognize call waiting, and buffer data while you answer the phone (or
>some such system?)  If not, why not?  Seems like a reasonable idea, providing

Since no data or carrier passes through the line while you talk on the
second, call waiting line, the hardware and software on both ends would
have to agree to suspend the "data conversation" until you returned to
the data line (most modems will drop the line on loss of carrier).  Even
if you could get the correct hardware/software combination, there is a
serious problem with allowing the modems to remain off-hook during loss
of carrier.  That problem is that the modem might confuse a real hangup
with a call waiting interruption (the remote end does not get the beep,
only a momentary interuption of signal).  If the computer leaves you
logged-in after a real loss of the line it would leave a serious security
hole.  Modern phone exchanges give an unambiguous hang-up signal so
the problem isn't as bad as I make it out to be, but it is worth
mentioning.  Also, the computer could prompt you for your password on
re-connect.  Modern phone exchanges also let you turn off call waiting
for a single phone call (better than getting disconnected, anyway).

David Kovar mentioned Data Over Voice (DOV) modems as a solution.
I wonder how they work?

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