John Hansen wrote:
>
> At 06:15 AM 11/4/98 -0800, you wrote:
> >Hello all,
> >   I am working on a PIC based telephone project which will
> >intercept and screen all incoming calls, without the phone ringing and
> >conditionally, based the screening criteria,
> >either issue a voice message or ring the phone and connect the phone to the
> >incoming line.
> >
> >Can anyone point me to information on how to carry out the
> >actual connect functions to the handset.  This is the only
> >part of the project I haven't figured out.
> >
> >Thanks in advance.
> >
> >
> >73,
> >Dan Welch
> >w6dfw@qsl.net
> >
>
> I've been looking into this as well.  My theory is that most of the automated
> calling services these days have about one second of silence after you pick up
> the phone, but before you are connected to the salesperson.  I think it should
> be possible to key off this delay to hang up on automated sales calls.  The
> problem is getting the pic chip to answer the phone and to hang up at the
> appropriate time (or to actually ring you if it is not a sales call).  In
> asking around about this, everybody I heard from said the best book on the
> subject was one that used to be sold by (believe it or not) Radio Shack.   I
> remember that book and now regret not having bought one, but it is no
> longer in
> print.  If you can find someone with a copy, I'd like to have one too!
>
> Best of luck with your project.
>
> John, W2FS

  That book was great!  It was written by some folks at Bell Labs, and
covered things pretty well - My copy has disappeared (apparently
forever), I'll HELP someone re-publish the darn thing (or buy multiple
copies!) if it can be re-published - If I'm lucky, my copy may
eventually re-surface, but don't hold your breath.  Good book.

  Mark, mwillis@nwlink.com