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The complexity of a network - telephone or computer - rises dramatically with the number of people connected to it. This was not something that had bothered people until the telephone became widespread, when it suddenly became really important.

If there are only a few people with telephones, the network is quite simple and everyone can be connected to everyone else. If there are more people, you need some sort of exchange to connect a call to another person through a central system.

But if there are thousands of people it gets much more complicated.

The different network topologies : rings and stars

The different network topologies : rings and stars

How does a switchboard work? : have a go yourself

How does a switchboard work? : have a go yourself

How the old Exchange worked

How the old Exchange worked

How the cell system works

Click and drag the phone around to see how adjacent cells arrange handoff so that it never loses the radio signal.

How the cell system works

Telephone operator trainee : Jean Elliott

Jean Elliott was born in Harrow, north London in 1924. She had had no experience with the phone until she joined the GPO at the age of 17, where her cousin already worked.

Jean was put through training at the Temple Bar exchange to become an operator, which as she recalls was quite a prestigious job to have at that time.

Here she recalls some of the pitfalls of her early training with the phone service, particularly the rigours of timekeeping.

audio clip


Well we had to sit at the switchboard with a supervisor besides us and she was connected also to this switchboard and so she knew exactly what was going on both ways and she could but in if we did the wrong thing. It was an automatic exchange so it was just if anybody had any of the trunk and toll calls and if anybody couldn't get through well they'd ring the operator. If you arrived five minutes late then that was booked against you and you had to stay late and do that five minutes - well they collected the minutes up and if they were short of a girl, a late duty girl, they'd say you'll have to stay half an hour tonight because you owe the department 30 minutes and you had to stay, there was no question about it.

fun and games

Can you beat our games? Explode equipment to see what's inside, hear the changing sounds of telecommunications, see how telecommunications designs have changed over time or send an e-postacard.

what's on

The UK's first permanent gallery dedicated to the history of information and communication technologies opens in the new Information Age gallery at London’s Science Museum.

audio history

Take a trip down memory lane with extracts of the interviews which have been recorded as part of the Connected Earth oral history programme.

featured story

100 years of automatic switching!
In 1912 the GPO installed Britain's first automatic telephone exchange in Epsom.

Discover the early days of the telephone...