How does Lecter dial the telephone in Red Dragon?

I was watching Red Dragon and Lecter is given a phone to talk to his lawyer with no dial on it. He hangs up on the lawyer and dials a different number by tapping the buttons at the top. Can someone tell me how this works? I am really curious.

Its called Pulse Dialing or Rotary or Decadic dialling in the United Kingdom, in which a direct-current pulse train is produced by interrupting a steady signal according to a fixed or formatted code for each digit and at a standard pulse repetition rate........ In other words:

The pulses are generated through the making and breaking of the telephone connection (akin to flicking a light switch on and off); the audible clicks are a side effect of this. As a result, all that is really needed to dial a number with pulse dialing is a switch. Each digit in the number is represented by a different number of rapid clicks. In most countries one click is used for the digit 1, two clicks for 2, and so on, with ten clicks for the digit 0. Two exceptions to this are New Zealand, with ten clicks for 0, nine clicks for 1, and so on, and Sweden, with one click for 0, two clicks for 1, and so on.