Here's how a typical telephone call works:

1. You pick up the receiver and listen for a dial tone. This lets you know that you have a connection to the local office of your telephone carrier.

2. You dial the number of the party you wish to talk to.

3. The call is routed through the switch at your local carrier to the party you are calling.

4. A connection is made between your telephone and the other party's line using several interconnected switches along the way.

5. The phone at the other end rings, and someone answers the call.

6. The connection opens the circuit.

7. You talk for a period of time and then hang up the receiver.

8. When you hang up, the circuit is closed, freeing your line and all the lines in between.