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 ...
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How does a switchboard work? : have a go yourselfVisit our interactive demonstration and try it for yourself. A new window will open.
How the old Exchange workedVisit our interactive Old Exchange demonstration and try it for yourself.
How the cell system worksVisit our interactive demonstration and try it for yourself. A new window will open.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.
Play the audio clip and view the transcript to learn more. A new window will open.