How Does A Traditional Landline Phone Operate?

Alexander Bell first invented the telephone in 1876. The technology he used has certainly stood the test of time because landline telephones still operate in a similar way today. The creation of the phone offered a rapid and reliable alternative form of communication to the postal service for households and businesses alike. Even today, advances in internet communications and cellular networks have not fully replaced the traditional telephone and most households and businesses keep their landline for low-cost and reliable phone calls.

A basic phone is comprised of a switch (hook switch) to connect and disconnect from the network, as well as a speaker and a microphone. The majority of modern phones use a component called a duplex coil to block the sound of your own voice, a bell and a touch-tone keypad. Often a mechanical bell is replaced with a speaker and circuit to create a ring tone.

The phone is connected to the network through a phone jack in the house. Pairs of copper wires from the phone jack run from the house to a box at the road called an entrance bridge. A thick cable of 100 copper wires or more then runs along the road and directly to the phone companys switch or concentrator in your local area.

The audio sample of your voice is then sampled at a rate of 8000 per second and transmitted down a fibre optic cable to the phone company office. In the days when a manual switchboard was in operation there were a pair of copper wires running from every house to a central office in town. When one person picked up the hook switch a connection was made and a light flashed above that persons jack on the switchboard. The operator would then connect their headset and ask the caller whom they would like to speak with. The operator would then send a ring signal to the recipient and once they had answered simply connect the two lines together.

At first the network of telephone numbers the operators used was small and numbers were relatively short, but as the network has grown to reach a global scale the length of numbers has also increased. Most countries use area codes to keep phone numbers as short as possible and often emergency services have a three-digit shorthand so they can be dialled quickly. Since every call is essentially tracked by the unique sequence of numbers it is possible to display a caller ID to the recipient. This is a feature that is incorporated into most modern household phones.