Corded vs cordless phones in power cuts

Last reviewed: 2026-03-04

How corded phones used to work

On the old analogue phone line, a corded phone drew its power directly from the telephone cable. No batteries. No mains plug. If the electricity went off, the phone still worked because the exchange supplied the power.

That is why people were told to keep a corded phone in the house for emergencies. It was good advice at the time.

Cordless phones have always needed mains power

A cordless phone has a base station that plugs into the wall socket. The handset talks to the base station wirelessly, and the base station connects to the phone line. If the power goes off, the base station stops and the handset is useless, even though the phone line itself may still be live.

This was true on the old analogue line and it is still true on digital voice.

What changes with digital voice

On a digital landline, your calls go through the broadband router instead of the old copper line. The router needs mains power to work. If the power goes off, the router shuts down and there is no phone service, regardless of what phone you have plugged in.

A corded phone plugged into the router's phone port does not need its own power supply. The router provides the power to the phone, just as the old exchange used to. But the router itself still needs mains electricity.

A cordless phone base station still needs its own mains connection, on top of the router needing power.

So on a digital landline, both types of phone depend on the router having power. The corded phone has one fewer point of failure (it does not need its own plug), but it cannot work without the router any more than a cordless phone can.

Does "keep a corded phone" still make sense?

Partly. A corded phone plugged into your router's phone port is still simpler and more reliable than a cordless phone, because it has no battery to go flat and no base station to fail. If the router has power, the corded phone will work.

But it no longer gives you a phone that works when the electricity is off. That was the whole point of the old advice, and it no longer applies.

What to do instead

If you need to make calls during a power cut, you have two practical options:

Battery backup for the router

A small battery backup unit (sometimes called a mini UPS) sits between the wall socket and the router. When the power goes off, the battery keeps the router running for a few hours. If the router has power, your landline works, corded or cordless.

Under Ofcom's rules on landline migration, your phone provider must offer at least one solution for making emergency calls during a power cut. Ask them what they provide.

See battery backup basics for a full explanation of the options.

A charged mobile phone

For most people with reasonable mobile signal, a charged mobile is the simplest backup. Keep a charger in the car or a power bank in a drawer, and check signal in different parts of the house.

See mobile fallback and signal for more on this.

Summary

See will my phone work in a power cut? for the full picture.