What is Modem in Computer Network? and How Modem works?

In this article, we will discuss what is modem in networking? How does it work? and also discuss the basic history of the modem device.


A modem is a hardware networking device that helps to convert signals from one computer network to another. It is used to connect the computer to the internet where it converts data signals into digital and analog forms.

Modem establishes and maintains a dedicated connection to your internet service provider (ISP) to give access to the internet.

It works as a signal translator because it translates one signal to another signal so the computers and telephone lines can interact with each other.



Why do we use a modem?

If we want to access the internet in our home or business, we should have a modem.
The main reason we have to use a modem is because there are two types of signals that are used when we connect our computer to the internet. Our computer can only understand digital signals, while the phone lines which help to connect the internet are works on analog signals.
A computer cannot communicate directly with your ISP phone lines, both the computer and the internet are works on different signal types that’s why we use a modem, which is used as a signal translator between your computer and the internet.

What is Modem in Networking

How Modem Works?

This term modem comes from Modulator and Demodulator

MO + DEM = Modulator, Demodulator

A computer or a machine can only understand digital signals (1’s and 0’s), but the telephone lines can only transmit data in analog form, so to convert the signals from digital to analog and analog to digital, we used a device called modem which comes from the term modulator and demodulator.
So a modem can modulate the signals and also demodulate the signals.

Modulate means to convert computer’s digital data signals into analog data signals so the data can travel on the internet.

Demodulate means to convert analog data signals from the internet into digital data signals so a computer can understand it.


You should also read: How Router Works, How NIC Works.



Types of Modem

Dial-up Modem:

  • Dial-up modems are the old technology-based modems, used with the telephone lines to connect with the internet by using the dial-up connections.
  • To use the dial-up modems, we had to dial the telephone number to connect with the internet.
  • To establish a dial-up connection, we need an active phone line that is not in use and we dial up the phone number (like we calling someone) to the receiver’s phone that’s attached to another computer.
  • When the connection is made, our computer can check emails, share files, etc.
  • The speed of the dial-up modems can only reach up to 56kbps due to technical limitations.

DSL Modem:

  • DSL means Digital Subscriber Line also called DSL broadband.
  • DSL modems are also used with the local telephone lines like dial-up, but they are totally different from the dial-up connections.
  • DSC uses separate frequencies for phones and the internet, so we can use both the phone and the internet at the same time.
  • It helps to connect a single computer or with the help of a DSL router, can connect multiple computers through multiple Ethernet ports.

External Modem:

  • As the name suggests, these types of modems are used externally, connected outside the computer using a cable.
  • External modems are easy to use, but they are a little bit expensive.
  • It provides a high-speed data transmission rate and helps to avoid interruption in network connectivity.

Internal Modem:

  • Those types of modems are installed on the computer’s motherboard.
  • Data transmission rates are slow.
  • They are not portable, and cannot move or replace easily from one computer to another and they are used for dedicated computers.



Basic History of the Modem

According to Wikipedia,

In 1958, the telephone line modems were used in the US for the air-defense system as a part of SAGE (Semi-Automatic Ground Environment). Their purpose was to connect various airbases, radar sites, and command centers with SAGE director centers, to expand throughout the USA and Canada.

In 1959, the first modem (called Bell 101 dataset/modem) was commercially released by AT&T Corporation, which data speeds around 110 bit/s.

In 1962, the second commercial modem (called Bell 103 dataset/modem) was released by AT&T Corporation, which provides full-duplex data transmission at the speed of around 300 bit/s.

In 1977, the world’s first PC modem (called Hayes 80-103A) was created by Dale Heatherington and Dennis Hayes. At that time this modem was very popular in the US because of its ability, which allowed a direct connection to the phone at the right price.

In 1996, the technology of 56k modem was invented by Dr. Brent Townshend.

In 1998, the first 56k modem was commercially released in the market at a reasonable price.


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