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How does information travel across phone lines?

As electrical signals, since they are electrical wires! Actually, the method used is being changed from "analog" to "digital" - you may have heard some of the long distance companies advertising, as are some of the cellular phone companies now, about how they use clear, sharp digital rather than analog. The old way was easier for voice-style communication because you just convert the analog sound waves of the voice directly into the analog signals of the telephone. A modem converts digital computer signals into analog telephone signals, for example, which seems an unnecessary step (you could just send the digital message directly as is done on ethernet's and other local area networks between computers).

Arthur Smith

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