ahsan1

for a simple PBX, you need the following stuff 1) 3 SLIC (88500) 2) Analog switch (8816) 3) DTMF receiver (8870) 4) Tone detector and external line circuit 5) Tone generator (sine wave generator 300-400 hz) 6) Controlling device (micro-controller) first go through all these thing and get the basic idea, then move toward designing.