Hi Matt et. al.

> > Think one who wanted to save money on long distance phone calls
> > with his cellular could call a close by voice phone number, then have the
> > voice phoner person call wherever the cellular person wanted and
> > connect the people by three-way calling? Anyway to automate this by
> > replacing the voice-phone person with a pic thing or switch?
>
> Yes, there is, but why bother? You won't save any money. You either pay
> long distance on the cell phone or on the landline, and you pay cellular
> airtime either way.

Sometimes Cellular long distance is at premium rates (not here).

> The hard part would be verifying that both voice parties did in fact get
> connected to each other.

I think much harder would be to detect when the calls were to be terminated
unless you force the initiator to send some more DTMF tones and hope you
do not drop out the Cellular call first.  You would be best served by adding
a functional call progress tone detector IC to your PIC and DTMF ICs
and this is all starting to be hard work.  Type arooval is a LOT of work.

There is a certain group of numbers near where I live that is local
to two trunk areas.  The local calls are 1/6 of the trunk calls but
you have to effectively make 2 of them and pay for two phones in the
intemediate area or one phone and the premium service charge for
3 party calling facilities.

However I think the PIC can be dispenced with completely if you can
subscribe to call forwarding that is programmable.  Just program
the new number into the landline forwarding service, call it and
let it forward the call, don't even have to write any code.

Cheers
--
Kalle Pihlajasaari   kalle@ip.co.za   http://www.ip.co.za/ip
Interface Products   P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750   Fax: 402-7751    http://www.ip.co.za/people/kalle

DonTronics, Silicon Studio and Wirz Electronics uP Product Dealer