How telephone exchange works?

Question

Explain in very few words how telephone exchange works?

Answer 1

You turn the crank on your phone and it sends a signal to the main telephone office that you want to make a call. The operator picks up and says, "number please." You tell her the number you want to call, and she plugs in a cable that routes your phone to the switchboard (exchange) of the place you're trying to call. The operator on the other end sends a signal to the phone you're trying to reach, and hopefully your party picks up.

Simple.

Answer 2

Like Zosh said, only now the operator and the patch board have been replaced by computer operated electronic switches.