Telephone land line and mobiles details

*when you ring up a friend, you phone sends a signal to your friend’s phone. This only takes a few seconds, even if you friend lives far away. Hoe does the signal travel?

Image via Wikipedia

Land lines

• When you dial number, your telephone sends a signal through the telephone wire.
• The wire carries the signal to a bigger wire called a cable, under the ground.
• The cable carries the signal to the telephone exchange. There are telephone exchanges all over the world.
• The computer in the telephone exchange read the number you have dialed and send the signal to the telephone exchange nearest you friend’s place.
• Some signals are sent along cables. If your friend lives in a far away city the signal may be sent through the air.
• The signal reaches the telephone exchange nearest your friend’s place.
• This exchange sends the signals to your friend’s telephone and it starts ringing.
• When your friend picks up the phone, the two phones get connected and can talk to each other.

Mobile phones

Image via Wikipedia

*Mobile phones send signals through the air; these signals are called radio waves. They can travels through the air and do not need wires.

Image via Wikipedia

So mobiles phones can be used almost everywhere. To make mobiles phones work `Transmitter towers’ than can pick up and send radio signals are made all signals are made all over the world.

• When you dial a number the mobile phone sends a radio message. It is picked up by the nearest transmitter tower.
• The transmitter tower sends the signal to the nearest telephone exchange.
• The telephone exchange sends the signal to number of transmitter towers.
• The phone you have dialed picks up signals from the nearest transmitter tower, and rings.