A signaling mechanismCusually incorporated within a telephone setCthat when rotated and released, generates dc pulses required for establishing a connection in a telephone system.

Remember your grandparents phone where you had to spin the wheel to get it to work? Well rotary dialing uses a sequence of pulses to represent different numbers that are dialed. (If you were quick enough you can rapidly hit the hookswitch 8 times to signify an 8 in a phone number).

The rotary dial is a device mounted on or in a telephone or switchboard that is designed to send interrupted electrical pulses, known as pulse dialing, corresponding to the number dialed. It was invented in 1888 by Almon Strowger. The device was phased out from the 1970s onwards with the onset of Touch Tone™ dialing, which uses a telephone keypad instead of a dial.