A modem or also known as a modulator-demodulator, is a computer hardware that’s used to convert digital data to a form that’s suitable for an analog transmission medium such as radio or telephone. It transfers data by modulating carrier wave signals to encode digital information. Modems are often used on any means of transmitting analog signals, like from a light-emitting-diode or LED to radio.

Table of Contents


The first generation of modems were used to transmit audible sounds that were suitable for telephone systems or leased lines. It operated around 110 to 300 bits per second (bits/s), and were controlled manually using a telephone handset attachment. In the 1970’s, modems with speeds of 1200 to 2400 bits/s were soon made available and used on dial and leased line connections.

By the 1980’s, cheaper dialup modems were released and were widely used on radio and other communication systems. As newer technology innovations were launched in the 1990s to early 2000s, modems reached a standard bandwidth of 56 kilobits per second (kbit/s). It also led to new encodings for internet and cable TV lines.

Public use of smartphones in the 2000s led to the development of improved radio-based systems. Now, it’s embedded in almost every mobile computing device in one form or another and is capable of transferring data up to hundreds of megabytes per second (Mbps).


Helpful Articles about Modems


Common Types of Modems

Dial-up Modem

Dial-up modems are devices that transmit computer data over a switched telephone that’s not designed for data use. The modulated data that’s transferred must fit the frequency of normal voice audio signals. Early dial-up modems relied on the communicating parties to dial and establish a voice connection before switching to line.

The fastest dial-up modems were developed and used in the 1990s, with a maximum ideal bandwidth of 56 kbit/s. It was made popular worldwide for dial-up internet access, paired with computers or desktops. However, it was soon replaced by broadband internet, such as a digital subscriber line or DSL.

Optical Modem

Modems that are used to connect to a fiber optic network are called an optical network terminal (ONT) or optical network unit (ONU). It’s used in fiber to the home systems, which are installed on a residential unit to convert the optical medium to a copper Ethernet interface, along with a router or gateway, for internet connection.

Broadband Modem

Broadband modems were used in place of dial-up modems in the early 2000s due to their capability to exceed the 56 kbit/s maximum bandwidth. Innovations such as the digital subscriber line (DSL) modems and cable broadband were all based on fundamental broadband technologies.

It used less sophisticated means of data transfer, since signals don’t pass through telephone exchanges and no dialing was required. Hence, broadband systems had higher frequencies and faster speeds. For instance, Asymmetric digital subscriber lines (ADSL) were designed to receive voice calls and initiate data transfer over the same line simultaneously.