|  | 2.2 | WAN Devices
| 2.2.3 | Describe modems on a WAN

A modem is a device that interprets digital and analog signals by modulating and demodulating the signal, enabling data to be transmitted over voice-grade telephone lines. At the source, digital signals are converted to a form suitable for transmission over analog communication facilities. At the destination, these analog signals are returned to their digital form. The Figure illustrates a simple modem-to-modem connection through a WAN.