Will Your Digital Landline Work During a Power Cut? A UK Guide

Usually, no. A UK digital landline normally stops working in a power cut because the phone service relies on powered equipment in your home. With a suitable battery backup or another emergency-calling solution, you may still be able to call 999 or 112. Do not assume a digital phone will remain available just because its handset looks like an old-fashioned landline.

This matters as the UK replaces its aging analogue telephone network with digital calling. The industry is working toward a January 2027 transition, although individual households may have different arrangements and migration dates. If you rely on your landline, the time to check its backup is before the lights go out. See the UK government’s switchover guidance.

Why digital landlines stop working when the electricity fails

Traditional analogue lines could supply enough electricity from the telephone exchange to run a basic corded handset during some local power cuts, provided the wider network stayed operational. A digital service, often called Digital Voice or VoIP, carries calls using an internet-protocol connection. Your broadband router, digital phone equipment and sometimes a separate fiber modem or optical network terminal (ONT) need power.

When the household supply fails, those devices generally switch off. Even a fully charged cordless handset may be useless if its base station or router has no electricity. A simple corded handset connected to the router does not, by itself, solve the problem.

On full-fiber connections, ask whether the ONT and router both need backup power. As Openreach’s equipment checks explains, fiber equipment also needs electricity. A battery can address a home power cut, but it cannot guarantee service if the provider’s network is damaged or offline.

Are providers required to give you free battery backup?

Yes, if you depend on your landline to reach emergency services during a power cut and do not have a workable alternative. Ofcom says providers must offer an appropriate solution free of charge in that situation. This could be a battery backup unit or another way of making emergency calls. The solution must provide access for at least one hour; some providers offer longer coverage.

That does not mean every digital landline customer automatically gets a free battery. The key question is whether you can reliably reach emergency services another way, for example with a working mobile phone and adequate mobile coverage. Providers must also identify and support customers with additional needs. Read Ofcom’s digital landline advice and Ofcom’s provider rules.

A one-hour minimum is not a promise that every power cut will end within an hour. If outages in your area tend to last longer, tell your provider and ask what extra resilience is available. For example, BT’s battery backup instructions describe units intended to power the necessary equipment for essential calls.

What about 999, 112 and mobile phones?

If your digital landline has no backup and its equipment is off, you should not expect it to make 999 or 112 calls. A charged mobile phone is a useful alternative. In the UK, an emergency call to 999 can connect via another mobile network when your usual network is unavailable, if a compatible network is accessible. It will not work if no suitable network is reachable.

Keep a mobile charged, consider a charged power bank, and make sure everyone in your household knows where the phone is. If you have poor indoor reception, ask your provider about the options before an emergency. Do not call 999 or 112 merely to test whether your equipment works; arrange a safe check with your provider instead. Ofcom also recommends preparing for communications outages in its Ofcom’s power-cut advice.

Extra precautions for telecare alarms and medical devices

If someone in your home uses a fall detector, care pendant, monitored alarm, health device or other equipment attached to the telephone line, contact both the phone provider and the device or monitoring-service provider. An older alarm may not reliably communicate over a digital line, even when voice calls appear to work. Battery backup for the router does not necessarily power the alarm itself.

Ask the equipment supplier to confirm compatibility, backup duration and how the alarm will signal for help during an outage. Do not disconnect or migrate a critical device until a compatible, tested arrangement is in place. Government October 2026 telecare guidance, published October 8, 2026, specifically warns that outdated analogue telecare and warden-call systems can become unreliable or stop working after migration.

Five things to check before the next power cut

1. Find out which phone service you have. If your handset plugs into a broadband router rather than an old telephone wall socket, it is likely digital. Your provider can confirm.
2. Tell your provider about your household’s needs. Explain if anyone relies on the landline for emergency calls, has no mobile, experiences poor signal, is disabled, or uses a care alarm.
3. Ask what stays powered. Find out whether a supplied battery covers the router, ONT, phone base and any necessary adapters. Check who installs or replaces it.
4. Confirm the backup duration and maintenance. Ask how long the arrangement will last, whether it needs charging or periodic replacement, and what to do during a longer outage.
5. Make a simple outage plan. Keep emergency contact numbers on paper, charge a mobile and power bank, agree how to check on vulnerable relatives, and consider a battery-powered radio.

What should you do if your provider is switching you now?

Read the provider’s letter, then call the customer service number printed on a recent bill or on its verified website. Explain your emergency-calling and telecare needs before agreeing to installation. Ask for the backup arrangements in writing and check who will test the complete setup. If an essential alarm is not compatible, request that the change be paused until a safe solution is ready, consistent with Ofcom’s digital landline advice.

Be wary of unexpected callers demanding payment or bank details to prevent your landline being cut off. Verify the request independently rather than using a number supplied by the caller; see Ofcom’s scam-call advice.

Can I buy my own UPS instead?

A properly sized uninterruptible power supply (UPS) may keep compatible equipment running during a brief power cut, but selecting one requires knowing the power draw and connectors for every device involved. Its advertised runtime may not reflect your actual setup. Ask your communications provider whether a third-party UPS is suitable, and never treat it as a substitute for a confirmed emergency-calling plan if you rely on your landline.

The bottom line: A digital landline does not automatically survive a power cut. Check what equipment needs electricity, arrange backup if you depend on the phone, and confirm that any connected care alarm works with the new service. Taking those steps now is safer than discovering a gap during an outage.