Telephone pick up problem

Hi
I am also trying to work on a telephone controlled switch. I also have the problem of answering. I saw the posted reply for "theego". I would appreciate it a lot if anyone could further share ideas with me. I intend it( the cct) to pick up the line(ie connect to the dtmf decoder) after the line rings for,say, about 5 times.
Do you know how I could achieve that?
any suggestion would be appreciated.

Rectify the ring signal to make pulses, count five of them then connect a load resistor across the line and connect the dtmf decoder.