Woman holds a mobile phone to her ear, c. 2011
A telephone (1876- ), or phone for short, is an invention that allows you to talk to someone far away. If you both have a telephone then you can hear each other’s voices through it and talk.
To talk to someone on his telephone you must know his telephone number and put it into yours. This is called dialing the number. Your telephone then calls his telephone. His telephone rings, telling him that someone wants to talk to him. If he answers his telephone, opening the connection between the two, you begin to talk. When you are both done, most likely a few minutes later, you hang up, ending the call.
The telephone was invented by Alexander Graham Bell in 1876, but it did not become common in America till the 1920s. In time each house and business had at least one. Making telephones was not the hard part – it was setting up the telephone network. All the telephones had to be connected together by lines of copper wire, called telephone lines.
A telephone uses the network to open a connection to another telephone. Then it converts your voice into something that can go through the network. When it gets to the telephone at the other end, it is converted back into your voice. The other person can then hear what you said.
Some of the sound in your voice is lost so that two people could sound alike. The sound quality is good enough for talking but not for singing.
In the 1990s mobile phones – also known as cellphones or handphones – became common. Instead of wires, they send calls through the air to a nearby tower. You can put a mobile phone in your pocket or your bag. You can call anyone almost anywhere.
Some mobile phones are now smartphones. They are pocket computers that can also go on the Internet.
When you call someone you are using a part of the network called a circuit. While the network is designed to handle thousands of calls at once, there is a limit. If everyone calls at the same time, like on 9/11, then the network will run out of circuits and you will hear a message that says, “All circuits are busy. Please try again later.”
The longer your call lasts and the longer the distance, the more of the network you are using up. The telephone company can charge you accordingly.
This way of running the network is called circuit switching. It was designed for a time before computers when human operators connected calls together on a big switchboard.
With computers you can run a telephone network the same way as the Internet using packet switching. This makes calls much cheaper, so cheap that time and distance barely matter. At first the Internet was not fast enough and good enough for telephone calls, but now it is. So in time most telephone calls will go over the Internet. Some already do.
Pictures of telephones through the years:
1919: Western Electric 51AL candlestick phone
1927: Western Electric Model 102
1949: Western Electric Model 500
1980: Western Electric Model 2500 touch-tone telephone
1999: Nokia 3210 mobile phone
2010: iPhone 4 smartphone
See also:
The telephone is a wonder. It brings people together and make the dissemination of ideas and goods much easier.
Thank goodness for the telephone!
Stephanie B.
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