Have a look at:
http://www.playground.net/~mwandel/pbx.html

- Keelan Lightfoot


>I've been looking for a general all-around telephone switching circuit.
>Something like a small PBX.
>
>I know there was an article / schematic / etc. a couple of years ago in
>Circuit Cellar, but haven't been able to find it or anything like it on
>the net.
>
>Ideally, it would except DTMF from an extension, direct 1 of 2 incoming
>lines to one of X number of extensions.
>
>Any circuits out there like that someone is willing to share.
>
>John Mullan