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Whenever you make a long distance call, there is an amazing amount of computer technology working to make your call happen! In order to understand the computerized systems used today, however, it is helpful to go back in time and look at how human beings once routed long distance calls.
Think back to a time when a human being worked in a town's central office. The phone company would build the central office in the middle of town, and then run a pair of copper wires to every home. The operator -- lets call her Mable -- would work in the central office. Mable would sit in front of a switchboard, and on this switchboard would be a collection of sockets -- one socket for each of the phones in town. When you wanted to place a call:
You would pick up your phone.
A light above your phone's socket would turn on.
Mable would plug a jack into your socket and ask you who you would like to talk to.
Mable would then plug her jack into the receiving party's socket, send a ring signal down the line, and talk to the person who answered.
Mable would then plug a wire between your jack and the receiving party's jack to connect the two of you together.
When she saw the lights go out above your jacks, Mable would remove the wire connecting the two sockets.
This was an incredibly simple system!
To allow long distance calls in this simple system, the local phone company would add a line (or multiple lines) to connect to a long distance office. To make a long distance call to your friend in this system, you would pick up your phone and tell Mable the long distance number for your friend. Then:
Mable would connect to one of the lines going to the long distance office.
She would speak to the operator in the long distance office.
The long distance operator would connect Mable to another long distance office -- the office for the area code of your friend.
Mable would tell the long distance operator the number, and she would connect to another office.
Eventually Mable would be able to talk to the operator in the central office for the town that your friend lives in.
That operator would make a connection to your friend.
Then Mable would connect you to the long distance line, and you would be able to have your conversation.
As you can see, this system is still remarkably simple. Your call was patched together with direct, physical wires going from one office to the next. The long distance operator would keep track of the length of your call and create a billing record.
The first act of automation was to replace Mable with a mechanical switch. When you placed a local call, the switch would connect you. To make a long distance call, you would dial "O" to speak to a human being, and the human being would connect the call through the long distance offices as before.
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