Question: how does a telephone work? How does the cable from the wall then connect to the telephone cables outside and then connect to somewhere in another country like Australia?

Tim Stephens answered on 26 Jun 2012:

The telephone uses a microphone to convert sound to electrical signals, and a speaker to convert the signal back to sound at the other end.

In the olden days, the telephone system was a lot more simple than it is today. The wire from the telephone in your house went to the local exchange where it was connected to a bank of switches. These then connected the wire to long distance telephone cables, which connected though other telephone exchanges to the one nearest whoever you were calling. That exchange then rang the telephone of your friend and connected you to them. It was one complete circuit.

Today it’s all a bit more complicated. There are computers in the telephone exchange that are connected to optical fibres, which are thin strands of glass that can carry light long distances. The sound of your voice is translated into digital signals, which are then sent through the optical fibre to the exchange at the other end where it’s decoded and sent to your friend’s telephone. The modern technology lets more people make a call at the same time (it used to be that only a few people could make a long-distance call at once), and the quality of the calls sounds much better.