Modem is abbreviation for Modulator – Demodulator. Modems are used for data transfer from one computer network to another computer network through telephone lines. The computer network works in digital mode, while analog technology is used for carrying massages across phone lines.

Functions:

• Error Correction: In this process the device checks if the information they receive is undamaged. It divides the information into packets called frames. Before sending this information, it tags each of the frames with checksums. Checksum is a method of checking redundancy in the data present on the computer. The device that receives the information, verifies if the information matches with checksums, sent by the error-correcting modem. If it fails to match with the checksum, the information is sent back.
• Compressing the Data: For compressing the data, it is sent together in many bits. The bits are grouped together by the device in order to compress them.
• Flow Control: Different devices vary in their speed of sending signals. Thus, it creates problems in receiving the signals if either one of them is slow. In the flow control mechanism, the slower one signals the faster one to pause, by sending a ‘character’. When it is ready to catch up with the faster one, a different character is sent, which in turn resumes the flow of signals.