To start the call a person (caller) picks up or activates the phone handset.
A computer at the Telephone Company detects the phone is “off hook” and places a dial tone on the line to alert the caller that the phone is ready for use.
The caller keys in the number desired.
The Telephone Company computer receives the dialed numbers from the caller and removes the dial tone from the caller’s line.
The Telephone Company computer then checks the line of the person being called for usage and options.
If the line being called is in use, and the called person has options like call forwardingvoicemailor other features for their line, the Telephone Company computer sends the caller there.
If the called person doesn’t have those options for their line the Telephone Company computer alerts the caller that the line is in use by sending back a busy signal
This illustration shows the entire telephone network,
including a home connection, cell phone towers,
long distance exchanges and transcontinental connections. You will be automatically redirected to howstuffworks.com!
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