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Path: utzoo!henry
From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: misc.consumers
Subject: Re: automatic sales calls
Message-ID: <7236@utzoo.UUCP>
Date: Thu, 16-Oct-86 13:53:51 EDT
Article-I.D.: utzoo.7236
Posted: Thu Oct 16 13:53:51 1986
Date-Received: Thu, 16-Oct-86 13:53:51 EDT
References: <5939@decwrl.DEC.COM>
Organization: U of Toronto Zoology
Lines: 23

> I believe with some electronic hacking, (and a capacitor) one can monitor
> the signal on the phone line while the line is ringing, so there is no need
> to fake the ring signal.  It depends on whether the phone company sends the
> signal from the caller's phone to the callee's phone while it is ringing.
> (which I believe it does, but I've never tried it)  If so, such a device is
> easy.

Monitoring the signal on the line during ringing is no big trick.  However,
only the older phone exchanges connect the two ends during ringing.  Newer
ones do not, because there is an obvious possibility of sending data or even
voice without ever picking up the phone.  Anything that permits unrecorded
calls is anathema to the phone company.  So whether or not this would work
is a function of what sort of equipment the phone company has on the other
end, which is subject to change without notice.

The simplest approach, actually, would be to include a buzzer or bell or
whatever in the monitoring box.  Ringing the phone bell itself is not
trivial, you need fairly high voltages and the right frequency (the bell
ringer is resonant at the ringing frequency).  Adding your own ringer
may be inelegant, but it's easier.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,decvax,pyramid}!utzoo!henry