so u need a dialling ckt from scratch.. r u intend to use PC in ur project..
case 1: if u use pc , and just need to dial a number , send atdt# (#is the number) to a modem, it will dial
case 2: ur usig a pc , but with no modem. u need a dmf encoder and a relay to make the off-hook condition(low resistance loop) and then send a seq: of bcd to the encoder from PC to dial.
case 3: u have no pc , no modem.. then u alteast need a micro: to provide timing , so that the digits be synchonously send to the encoder
which part describes ur need best.?