What is Dial up Modem : Top Manufacturers & Companies

A dial up modem is a communication device that enables data transmission over traditional telephone lines by converting digital computer signals into analog signals and vice versa. Widely used during the early internet era, dial up modems provided network connectivity for homes and businesses, supporting email, web browsing, file transfers and remote communications.

“Modem” is short for “modulator-demodulator.”

A dial-up modem is used to establish an internet connection using the existing plain old telephone exchange via a telephone line in a home or office. This setup is shown in the figure below. A dial-up modem will have two ports: one is a voice port where the telephone line is connected, and the other is a data port where the PC is connected.

It provides a lower data rate connection compared to other modem technologies but requires less investment if one has an analog telephone line. The disadvantage of dial-up internet is that if one uses the internet, the same telephone line cannot be used for making or receiving voice calls.

ITU-T (formerly CCITT) has classified various standards based on the data rate/modulation type the dial-up modem supports. These are referred to as the V series of standards. A few are summarized below.

A dial-up modem converts digital data into an analog form compatible with being transported via an analog telephone line.

Standards

• ITU V.21 - Audio FSK, 300 bps
• ITU V.22 - PSK, 1200 bps
• V.32 - 9600 bps
• V.34 - 28.8 Kbps and 33.6 Kbps options, backward compatible with V.32
• V.90 - 56 Kbps
• V.92 - Transmits at the same speed as V.90 with some additional features

Protocols Supported

PPP (Point-to-Point Protocol) is used in dial-up modems to establish a connection with the ISP’s server. It has more features compared to its predecessor, SLIP (Serial Line Internet Protocol). PPP is defined in RFC 1661.

PPP is regarded as a data link layer protocol and is interfaced with the network layer of the system to establish the TCP/IP connection with the peer entity.

Dial-up Modem Manufacturers

The following table lists dial-up modem manufacturers:

Manufacturer Name	Website
Conexant	www.conexant.com
Zoom Telephonics	www.zoomtel.com
Ikanos	www.ikanos.com
D-Link	www.dlink.com
Linksys-Cisco
BESTDATA	www.bestdata.com/

Summary

A dial-up modem is a hardware device that connects computers to the internet through standard telephone networks by converting digital and analog signals. Leading modem manufacturers developed dial-up solutions that enabled internet access, remote networking, and data communication before the widespread adoption of broadband technologies.