Modem: what connects your device to the internet
A modem is a device or chip that converts signals from a communications line (fibre, cable, phone line or a mobile network's radio signal) into digital data a computer or router understands, and back again.
In plain words
A modem is like an interpreter between two languages: the language of the "pipe" (light in fibre or radio waves from a tower) and the language of your devices. The router is the dispatcher who shares out what has been translated among everyone at home. Often the interpreter and the dispatcher live in the same box.
How it works
- The modem receives the signal from your provider or operator.
- It demodulates the signal, turning it into digital data.
- When sending data, it modulates it back into a line signal.
- A router (separate or built in) shares the data with your devices.
- In a phone, the modem is part of the chip or a separate chip.
Where you'll see it
Fibre terminals (ONT/ONU) from your provider, DOCSIS cable modems, ADSL modems, 4G/5G modems and routers, USB modems, and phones' built-in modems (Snapdragon X, Exynos Modem, Apple C1).
Does it matter when buying
For home internet, your provider usually supplies the modem. For a holiday home, a 4G/5G modem or router with good band support. In a phone, modem quality affects how stable the connection is when the signal is weak.
Myths
- Myth: A modem and a router are the same thing. Reality: A modem "translates" the line signal; a router distributes the network around your home.
- Myth: Modems are obsolete. Reality: Without a modem you cannot connect to any provider's or operator's network.
FAQ
What is an ONT?
An optical network terminal - a modem for fibre broadband.
Can I replace my provider's modem with my own?
Sometimes, but check with your provider.
What is a USB modem?
A modem for mobile internet that plugs into a laptop or router.