Dial
pulsing. An old method of
signalling dialed
digits on a
phone line (most commonly on the
local loop). Each digit is transmitted by opening the circuit that number of times; `
0' is transmitted by opening the circuit
10 times (this is why it is at the end of a
rotary dial). This happens at some (almost) fixed rate; pauses between digits are guaranteed by the time it takes to dial the next digit. The rate is achieved by a
centrifugal friction device on the dial mechanism.
You may simulate DP on any line by tapping the cradle at the correct rate; on some switches, you'll need to tap the cradle one more time than the digit you're dialing.