The rotary dial was introduced for use with automatic switching
equipment. The earliest dials had an eleventh finger hole labeled
"Operator." This was added to reassure subscribers that they would
not find themselves talking to the operator when they dialed a "0"
as part of a telephone number. Dialing "Operator" sent the same
signal as dialing "0." When people became used to dialing, this
extra position was not necessary.
When making a call, you use the finger hole corresponding to a
digit to rotate the dial to the stopper. When the dial is released,
it spins back to its resting position. As it spins, it makes and
breaks the dialing circuit. The number of times it makes the circuit
corresponds to the digit dialed: The farther the dial spins on the
return, the more times it makes and breaks the circuit. The number
of pulses sent from the dial operates a system of electromagnets in
the switching system to make the connection for the number dialed.
If you listen carefully when using a rotary telephone, you can hear
the clicks as the circuit is made and broken behind the dial.
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Heritage Community Foundation and
Telephone Historical Centre All Rights Reserved