Modem And Its Types

A modem is a device that modulates or demodulates the signals. The modem receives a digital signal from a networking device (i.e., PC, laptop), converts it into an analog signal, and transmits it to an ISP and vice versa. Speed is dependent on the type and cost of the modem being used. 

A modem typically has just two main ports:

  • WAN/Line Port: This connects to the ISP’s line (e.g., phone line, coaxial cable, or fiber, depending on the modem type).
  • LAN/Ethernet Port: This connects to either a computer directly or to a router for sharing the internet with multiple devices.
A device can work without a modem, but it depends on how it connects to the network.

1. If the Internet Connection Is Digital (e.g., Ethernet or Fiber with ONT):

  • Devices like computers, laptops, and routers can connect directly using Ethernet cables.
  • In this case, there’s no need for a modem, because the network is already digital.
  • Example: LANs (Local Area Networks), or a fiber connection that uses an ONT (Optical Network Terminal).

2. If the Network Uses Analog Signals (e.g., phone lines, old DSL):

  • A modem is required to convert digital data from your device into analog signals, and vice versa.
  • Without a modem, your device wouldn’t understand the signal—it’s like trying to listen to a song in a language you don’t know.

The modem comes first at the physical layer, when converting digital to analog for transmission, and then repeaters may be used along the path to keep that signal strong.

Need for a Modem

The internet sometimes uses analog communication channels (like telephone lines), but computers can only understand digital data. To bridge this gap, we use a modem, a device that converts digital signals to analog (for sending) and analog to digital (for receiving), allowing digital devices to communicate over analog systems.

Types of Modem

The way of  data transmission and how it is installed modem is of two major types

types of modems (internal and external modems)

1. Internal Modem

It is mounted into an expansion slot of the motherboard. It is used for the dedicated computer, and data transmission speed is also slow.

Internal modems are of two types.

  • Dial-up: it uses telephone lines and requires a network access phone number and login information (i.e., username and login ID) to make a connection.
  • Wireless (Wi-Fi): It connects wirelessly and without credentials in certain cases by using Wi-Fi.

Note: dial-up modem can work as external modem as well

2. External Modem

it is connected outside the computer system using a cable and provides a high data transmission rate. So, it is expensive.

Some types of external modems include:

  • USB Modem
  • Cable Modem
  • DSL (digital subscriber line) Modem
  • External wireless modems

Internal Vs. External Modem

A comparison of Internal vs. External Modem is given below

S.No. Internal Modem External Modem
1 It is powered by a PC. It needs an external power supply.
2. It is present inside the computer. It is present outside the computer.
3. It can be inserted into an expansion slot. It cannot be inserted into the expansion slot.
4. It is incompatible with different PCs. It is compatible with all kinds of PCs.
5. Its Price is low because no extra hardware is needed It is high in price. It requires extra cable and setup.