Your landline in a power cut: the digital switch explained

Why the old rule no longer holds

For decades, a basic corded phone kept working in a power cut. The old copper line carried a small amount of power from the telephone exchange, so the phone didn't need your electricity.

Digital landlines work differently. GOV.UK says a digital line can't carry a power connection, so the handset and the router both need power at home. Ofcom puts it plainly: digital landlines need mains electricity and won't work in a power cut unless there is a battery back-up. That includes calls to 999.

Ofcom says BT plans to retire its old analogue network by 31 January 2027. Virgin Media O2 and KCOM also plan to retire theirs, but Ofcom says their dates haven't been set. Many homes have already been moved.

Who gets a free battery back-up

Ofcom's rule: if you rely on your landline because you don't have a working mobile phone or a reliable mobile signal, your provider must offer you a free back-up, such as a battery unit for your home.

• It must last at least one hour in a power cut.
• Ofcom says some providers offer units that last up to seven hours.
• Be Ready says vulnerable customers, including telecare users, are entitled to a free back-up battery.

If you have a mobile with signal at home, Ofcom says that is a practical alternative for most people. A 999 call from a mobile will connect through another network if yours is down and another one is available.

Ask now, not during a storm. Ring the number on your bill and ask: when will my line move to digital, what back-up do you offer in a power cut, and can you note on my account that I rely on the landline?

The corded-phone myth

Many people keep an old corded phone "for power cuts". On a digital line, that phone plugs into the router, not the wall. If the router has no power, the corded phone is dead too. It only helps if the router is kept running, for example by the provider's battery unit.

Citizens Advice still says an analogue phone on an analogue line will work in a power cut. That's true, but it only applies while your line is still analogue. Check with your provider.

Telecare, pendants and health devices

Ofcom says a care alarm or telecare device might not work properly on a digital landline. GOV.UK adds that telecare devices may not work in a power cut. Citizens Advice notes that personal alarms that rely on wifi can stop when the power goes.

What to do:

• Tell your landline provider and the alarm supplier that the line has telecare. Ofcom says the provider can make arrangements, including pausing the change until a safe solution is in place.
• Before you buy a new alarm or device, ask the maker whether it works on a digital line (Ofcom).
• Ask what happens to the alarm in a power cut, and how long its own battery lasts.
• Be Ready also mentions connected health devices, such as diabetes sensors. Check how yours behaves if broadband or the mobile network goes down.

If you help an older relative, this is a good thing to check on your next visit.

If 999 won't connect

Be Ready's advice if you can't reach 999 or 112:

1. Try from both a mobile and a landline, as one may still work.
2. If your mobile network is down but wifi works, turn on WiFi Calling.
3. If you still can't get through and it is safe, go for help in person: a police station, fire station, ambulance station or hospital, or flag down emergency responders.

A simple back-up plan

• Keep a mobile charged and a power bank topped up. See how to keep your phone charged in a power cut.
• Keep a paper list of important numbers, as Be Ready suggests, in case your phone dies or you can't reach your contacts.
• Keep a battery or wind-up FM radio for news, and write down the frequencies of the stations you use (Be Ready). See choosing an emergency radio.
• Know the power cut number: 105 in England, Scotland and Wales, 03457 643 643 in Northern Ireland (Be Ready).
• If someone at home is older, disabled, has a long-term condition or relies on powered medical equipment, ask the energy company and network operator to add them to the Priority Services Register. Ofgem says it gives priority support in an emergency and advance notice of planned power cuts where possible.
• If you can't call anyone, agree in advance who will visit in person. Our post on reaching family when mobiles go down covers a family plan.

Scam warning: GOV.UK says to make sure messages really come from your provider and aren't marketing. Our general advice (not an official rule): if a call about "the digital switch" asks for payment or bank details, hang up and ring your provider on the number on your bill.

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Related guides

• The digital landline switch: will your phone work in a power cut?
• Broadband and phone outages: what to do, and how to prepare
• Priority Services Register: a plain guide
• Emergency planning for older people and carers (UK)
• Emergency planning for disabled people and carers

Free tools

• Priority Services Register checker
• Power cuts near me

We're an independent UK site, not the government. We check guides against official sources and link to them. In an emergency call 999.

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