How to Keep Your Home Phone Working During a Power Cut in the UK

Old landline phones had one quiet superpower: they kept working when the power went out, because the phone line itself supplied a small amount of power. Digital home phones do not work that way. Once your phone runs through a broadband router, a power cut takes the router down with it, and your home phone goes silent too. With the UK’s move to digital voice, this is a change every household should plan for, especially if anyone in the home relies on the phone in an emergency.

Step 1: Understand what stops working in a power cut

Start by working out which parts of your setup depend on mains power. A digital voice phone plugs into your broadband router, and the router needs electricity. If the power goes out, the router switches off, your broadband drops, and the digital phone service stops with it. Cordless handsets add a second problem, because their base station also needs power and the handsets themselves run on rechargeable batteries that drain over time.

Mobile phones are the obvious backup, but they have their own limits. A power cut can also knock out nearby mobile masts if their backup batteries run down, and your own phone battery will drain faster if the signal is weak. Treat your mobile as one layer of backup, not the whole plan, and keep it charged as part of your routine.

Step 2: Ask your provider about a battery backup unit

Many UK broadband providers offer a battery backup unit for customers who depend on their landline, and vulnerable customers can often get one free of charge. The unit sits between the mains and your router, and it keeps the router running for a limited time when the power fails, typically long enough to make and receive calls while the outage is dealt with.

Call your provider and explain your situation, especially if anyone in the household uses a telecare alarm, has a medical condition, or has no mobile phone. Ask three questions: whether you qualify for a free backup unit, how long it will power your router, and whether it also powers your phone handset or only the router. Write down the answers and the date of the call, so you have a record if anything needs chasing later.

If your provider does not offer a unit, you can buy a small uninterruptible power supply, often called a UPS, from an electronics retailer. Choose one rated for routers, check that it has enough capacity for your router’s power draw, and test it once it arrives rather than leaving it in the box.

Step 3: Keep a charged mobile phone as your second line

A charged mobile is the simplest backup, and it becomes far more useful with a few habits. Keep your phone charged above half whenever a storm or planned outage is forecast, and keep a portable power bank charged and in a known place. A power bank that can recharge your phone two or three times costs little and can cover a long outage.

Save the numbers that matter most in a place you can reach without the internet. That includes family members, neighbours, your GP surgery, your power network operator, and your telecare provider if you have one. In the UK you can report a power cut and get updates by calling 105, which connects you to your local electricity network operator free of charge. Store 105 in your phone now, while you are thinking about it.

Step 4: Use a corded phone if you can

If your setup allows it, keep one simple corded phone that plugs directly into the router’s phone socket. Corded phones draw their power from the router connection, so as long as the router has backup power, the corded phone will work. This matters because cordless handsets stop working as soon as their base station loses power, even if the router is still running on a battery unit.

You do not need an expensive handset. A basic corded phone is cheap, it has no batteries to go flat, and it can live in a drawer until it is needed. Test it once after you set it up, so you know it works and you are not discovering a faulty cable during an actual outage.

Step 5: Make a simple power cut plan for the household

Write down a short plan and stick it somewhere visible, such as on the fridge. It should say where the torch and power bank live, where the battery backup unit is and how to check it, and who to call first. If someone in the household uses a telecare alarm, note what happens to that alarm in a power cut and what the telecare provider advised, because some alarms have their own battery backup and some do not.

Step 6: Know what to do when the power comes back

When power returns, your router will usually reconnect by itself within a few minutes. If it does not, switch it off, wait thirty seconds, and switch it back on. Check that your home phone has a dial tone before you assume everything is normal, and check that any telecare alarm has reconnected. If the alarm shows a fault light or your provider’s app reports a problem, call the telecare provider straight away rather than waiting for the next test.

Frequently Asked Questions

How long will a battery backup unit keep my router running?

It depends on the unit and your router, but many provider supplied units are designed to keep a router running for around an hour, which is enough for most short outages and emergency calls. Larger units bought separately can last several hours. Ask your provider for the expected runtime of your specific unit, and test it so you know the real figure for your home.

Will my telecare alarm still work in a power cut?

Many modern telecare alarms have their own battery backup, but older units may depend on the phone line or mains power. Contact your telecare provider and ask directly what happens to your exact model during a power cut, and whether it needs a separate battery or a digital upgrade. Never assume it will work without checking.

Is a mobile phone enough backup on its own?

A mobile is a good backup but not a complete plan. Signal can weaken during a widespread outage, batteries drain, and not everyone in the household may have a mobile or know how to use one under stress. Pair the mobile with a battery backup unit or a corded phone, and keep the important numbers saved where anyone in the home can find them.