A large part of phone automation uses DTMF signaling. DTMF stands for Dual Tone Multi Frequency and has been in place since the 1960s. Dialing a phone number before the advent of DTMF involved using a rotor. The spinning dial would generate a number of pulses that the phone company would interpret as a number. The phone company then placed each number in order and after a set number was reached, the phone company would place the call. We still … Continue reading DTMF Automation