Computers that are connected to a telephone line incorporate a device called a modem. It turns signals into a form that can be transmitted along the telephone line. The name ‘modem’ comes from the term Modulator-Demodulator. The device modulates, or changes, the digital signal from a computer into an analogue signal, which is the type of signal that travels along telephone lines. The modem decodes or demodulates the signals it receives back so they can be read by the computer.
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