Broadband power cut: what happens to your wifi and landline
A broadband power cut knocks out your wifi the moment the lights go off, because your router needs mains electricity to run. If you still use a landline for calls, that goes down too, unless you’ve got a battery backup in place. That’s a big change from the old copper phone line, which carried its own tiny current and kept working even when the power was out.
Most households don’t think about a broadband power cut until it happens. Then it’s dark, the wifi’s gone, mobile signal might be patchy, and there’s no way to call anyone from the landline. Ofcom has rules to soften that gap. They only help if you know they exist, though, and actually check you’re covered rather than assuming the supplier sorted it when you signed up.
It catches people out because full fibre and other digital landlines are wired differently to the old copper network. A traditional analogue phone line carried a small current from the exchange, so the handset kept working in a blackout. Digital voice services run over your broadband connection instead, which means a broadband power cut takes the phone line down along with the wifi unless there’s a battery in the loop somewhere.
Why this storm season matters for your broadband
The UK’s storm season officially began on 1 September 2026, and the Met Office has already released its new list of storm names for 2026-27, including Austen, Boelo and Chloe, chosen by public vote (checked September 2026). Named storms bring exactly the kind of weather that causes local power cuts, usually with little warning.
At the same time, more UK homes are moving from analogue to digital landlines ahead of the full phone network switch-off, now expected by the end of January 2027. Every household that makes that move is one storm away from a broadband power cut with no working phone line, unless it’s planned for. Even our own Roo, who’s spent enough time on building sites to know a torch app isn’t a plan, keeps a battery pack by the router at home.
Do you need a battery backup for your router?
Yes, if you or anyone in your home relies on a landline to make calls, particularly in an emergency. Ofcom requires providers to keep landline customers able to reach 999 for at least one hour during a broadband power cut, and to give a free backup solution to people who depend on their home phone, including many on the Priority Services Register (checked September 2026, Ofcom).
If you’re mainly a mobile phone user with broadband as a bonus, a battery backup is still useful but less critical. Anyone on the Priority Services Register, elderly, disabled, or without reliable mobile signal at home should ask their provider directly whether they qualify for a free unit. It’s worth reading up on how Ofcom’s wider power cut rules for phone signal work too, since mobile networks have their own separate resilience requirements.
Asking is usually straightforward. Call your provider’s customer service line, or check their website, and ask specifically whether you’re eligible for a free battery backup unit under Ofcom’s landline rules. You may need to confirm you’re on the Priority Services Register or explain that you have no reliable mobile signal at home, so it helps to have those details ready before you call. If you’ve recently moved onto a digital landline as part of the wider landline switch-off, this is exactly the moment to ask.
How long does a broadband battery backup last?
The legal minimum is around one hour of standby power, enough to reach emergency services during a broadband power cut. In practice, several providers now go further. Vodafone, BT, KCOM and Zen Internet have all brought battery backup units to market that can keep a router running for roughly four to seven hours, depending on how the device is used (checked September 2026).
Some reports put the retail value of these units at around £150, though eligible customers are generally given one free rather than asked to buy it. Worth a proper look behind the router, honestly. Some backup devices are built into the box itself and others sit alongside it as a separate unit with its own little battery light, and plenty of people have one without realising.
What to do before the next storm hits
You can’t stop a broadband power cut happening, but you can make sure it doesn’t catch your household out. A few checks now save a stressful evening later, especially if anyone at home depends on the landline.
Key takeaways
- Ask your provider whether you qualify for a free battery backup unit for your router.
- Check you’re registered on the Priority Services Register if you or someone in your home is vulnerable.
- Keep a mobile phone charged as a backup way to make calls if broadband and landline both fail.
- If a storm is forecast, charge any existing battery backup device the night before.
- Know where your nearest public payphone is, or a neighbour on a different network, as a last resort.
It’s also worth factoring a provider’s power cut policy into any switching decision, not just the monthly price. Some providers are clearer than others about who gets a free backup device and how long it lasts, and that’s a genuine point of difference when you’re comparing deals.
Frequently asked questions about broadband power cuts
- Will my broadband work in a power cut?
- No, not without a battery backup. A standard router needs mains power, so a broadband power cut cuts your wifi and any digital landline calls straight away.
- Do all broadband customers get a free battery backup?
- No. Ofcom’s rule covers people who depend on their landline for calls, including many on the Priority Services Register. Everyone else can usually buy a backup unit separately, so it’s worth checking eligibility with your own provider (checked September 2026).
- How long will a battery backup keep my broadband running in a power cut?
- The legal minimum is about one hour of access to emergency calls. Some newer devices from providers such as Vodafone, BT, KCOM and Zen can run for roughly four to seven hours depending on use.
- What should I do if my broadband goes down in a storm?
- Keep a charged mobile phone as a backup, check your provider’s app or status page for known local outages, and confirm your battery backup unit is charged if a storm has been named and forecast.
- Can I buy my own battery backup for my router?
- Yes, standalone UPS-style units are available to buy. It’s worth checking with your provider first though, since eligible customers can often get one free rather than paying for their own broadband power cut protection.
