The terms modem, gateway and router are often used interchangeably and it can sometimes be difficult to discern the differences between them. However they are all different types of device with varying uses and specialisations.

 

What is a Modem?

A modem, or modular demodulator, is a hardware device that converts data encoded in a digital format designed for communication with devices into something that is suitable for network transmission like WiFi or Ethernet cabling. This is known as modulating and demodulating signals.

Standalone modems can be used to feed into a single device, like a computer, or feed into a network by connecting to a router. Many routers even have modems built into them so they can encode and decode digital data on their own; modems and routers both have their niche uses as standalone devices but their most widespread uses in networks are when they’re combined together.

An example of a modem would be Teltonika’s TRM250. This is a cellular modem, so it would convert the 4G signal data into electrical signal data so that it can be transmitted to non-cellular hardware.

 

What is a Router?

A router is a networking device that routes data packets travelling within a network environment, guiding them to and from their destinations. They will often act as the primary hub of a LAN (Local Area Network) and can also transmit data from a LAN to a WAN (Wide Area Network) and vice-versa.

As previously stated, many routers come with modems built into them so that they can connect to external WANs on their own (i.e. the internet). For example, the RUT200 comes with a built-in cellular modem to allow it to transmit data to and from the mobile network.

Routers also come equipped with various interfaces in order to interact with various types of hardware and fulfil several different applications. Common-such interfaces include Ethernet, RSRP and WiFi but more specialised niche interfaces can also be present, such as RS232 and RS485 which are often used with data monitoring equipment.

A typical home or small office router will simply forward IP packets between computers and the Internet, but more expensive enterprise routers are used to connect large businesses or Internet Service Provider (ISP) networks to powerful core routers that forward data at high speed along the optical fibre lines of the Internet backbone.

Most modern routers come with numerous sophisticated features that allow you to use them at a higher level, such as firewalls, VPNs and QoS utilities.

 

What is a Gateway?

A gateway is a piece of network hardware or software used to connect two separate networks together, which can be two different LANs or a LAN and a WAN.

A gateway is similar in some ways to a router but is generally much more niche. Rather than supporting multiple interfaces, a gateway will often use just one, typically rendering them simpler to install and more cost-efficient than an alternative router system. They will often be used for granting internet access to data-monitoring equipment, machinery or even IP cameras which aren’t part of a LAN environment.

Internet of things (IoT) gateways like the TRB501 act as a bridge, or protocol convertor, between other IoT devices and the Internet (often a cloud server). IoT gateways provide a communication link between the field and cloud as well as provide offline services and real-time control of devices.
 

 

In summary, a modem converts digital and analogue signals, a gateway is used to connect two separate networks together using one interface and a router is used to route data packages around a network. Many routers will come with built-in modem and gateway functionalities already, so standalone modems and gateways are usually only needed for niche situations and specialised equipment.