push-button dialing

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References

Images

On the left, a hand dials a number on a green rotary phone above a graph showing pulses (interruptions in DC current) that represent the phone being dialed. On the right, a hand presses a button on a red tone-dial phone above a representation of a push-button pad showing frequencies corresponding to each button.

Evolution of the Phone

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push-button dialing: Media

telephones

Images

On the left, a hand dials a number on a green rotary phone above a graph showing pulses (interruptions in DC current) that represent the phone being dialed. On the right, a hand presses a button on a red tone-dial phone above a representation of a push-button pad showing frequencies corresponding to each button.

Two methods of call-number signaling in a telephone system

A major component of any telephone system is signaling. (Left) For telephones with...

Encyclopædia Britannica, Inc.

Interactives

Evolution of the Phone

Evolution of the Phone

A look at telephone technology through the decades.

Encyclopædia Britannica, Inc.