Which one works as both an output and input device?

✔A modulator demodulator, or simply a modem, is a hardware device that converts data from a digital format.

✔A modem modulates and demodulates electrical signals sent through phone lines, coaxial cables, or other types of wiring;

✔It transforms digital information from your computer into analog signals that can transmit over wires, and it can translate incoming analog signals back into digital data