A modem is connected in between a telephone line and a ________.

Concept

A modem (modulator-demodulator) is the device that lets a computer exchange data over an ordinary telephone line. It converts the computer's digital signals into analog tones the phone line can carry (modulation) and converts incoming analog tones back into digital data (demodulation).

Applying it here

The telephone line carries analog signals while a computer works with digital data, so the modem sits exactly at that boundary. One end of the modem faces the telephone line; the other end faces the computer that owns the data. The device on the far side of the modem from the telephone line is therefore the computer.

Cross-check

Trace the data path end to end: computer to modem to telephone line to a distant modem to a distant computer. The modem's local endpoint is always the computer that produces and consumes the data, which confirms the answer.