> Hi,
>
> Not directly related to PICs, but I'm building a phone transmitter
> with a 16C84.
>
> My problem: I'd like to phone somebody and to detect when the
> callee has lift the receiver. Idea anybody ?
>
> Thanks,

> Fabrice POPINEAU

Hi,

If i've understood you're requirements:

Firstly, you'll need a line interface which depends on the country of
use and you may well have to gain approval to attach to the local
phone system.

Secondly, use a dtmf encoder (Most major semis do 'em, look on web
for circuits) to dial which will easily interface to PIC's.

Thirdly, you'll need some filters to detect tones. ie engaged tone,
ringing tone. If you detect ringing tone and then it disappears
someone's answered. Better system will look for engaged tone and give
up for a while and retry later.

Regards,
Greg Plummer