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From: "Jim Pennell"
Subject: Re: Telephone Ring Suppressor
Date: Sat, 21 Sep 2002 18:42:44 -0700
Organization: MindSpring Enterprises
X-Server-Date: 22 Sep 2002 01:42:47 GMT
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
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I built an anti-telemarketer system which did something similar... I
disconnected the phone until my computer had identified the caller as
"friend or foe"
My 'personal' answering machine was on the same side of the relay as the
phone I wanted to ring for a real phone call so either I would get it or my
answering machine would.
Actually, I used a relay to disconnect the phone and activated it when I
wanted to get the call using a control from a parallel port pin. I also
used an external modem with CID built in so it would deliver the CID number
to my computer's RS232 port. This was an old laptop and it was most
convenient to be able to use simple com port messages to set the modem up
and capture the CID response into my program.
I did buy a cheapie answering machine for the telemarketers to listen to
which was connected to the phone line when the relay was not activated...
And on that one I recorded the three tone 'DISCONNECTED LINE' beeps. If
they got through that, they got a fairly nasty message about how I know they
are a telemarketer and this was all they'd EVER reach.... If they still
wanted to leave a message, MAYBE it would be listened to. Someday.
That answering machine covered the remote chance of a call my computer
misrouted that I would really want to hear.
The blocked number message on the CID packet is different than the one
sent when there is literally no CID number.
I based the program on the assumption that a blocked number was almost
certainly from a private party and hence more likely to be a call I'd want
Of course, NO CID NUMBER was pretty much guaranteed to be a telemarketer
and it got dumped into an answering machine without bothering me.
These days I am using a telezapper, but they are starting to program
around that gizmo and I may rebuild my old CID based system. I think I
still have most of the parts....
What I really want is a wall powered CID device that outputs RS232 which
is actually a really simple device, but all I've seen in the stores just
show an LCD display. Given that, a real simple PIC or some such could do
the decision making and the entire gadget would be pretty small.
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