Does Wi-Fi work in a power cut? Broadband, landlines and 999

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No. Your home Wi-Fi needs mains power, so it stops in a power cut unless your broadband has a backup power source. Ofcom says home broadband, including any digital landline, will not work during a power cut without an additional power source. For most people, Ofcom says, a mobile phone is a practical alternative.

Quick answer

Home broadband and Wi-Fi stop in a power cut unless they have backup power, and so do digital landlines. Use your mobile instead. In the UK, a mobile can call 999 or 112 free through another network if yours is down. In the US, the FCC says broadband phone service needs a battery to work in an outage.

Why does my Wi-Fi stop working in a power cut?

Your router and broadband equipment run on mains electricity. When the power goes, they go too. The 105 power cut service lists internet and phones among the things that won't work without power, along with gas boilers, hobs and heat pumps.

Ofcom, the UK communications regulator, advises considering a battery backup power solution for your home broadband.

The FCC, the US regulator, gives two other options when the power is out: you may be able to connect to secure Wi-Fi if it's available nearby, or charge your phone from a charged laptop or tablet with a USB cable, though doing so may drain the computer's battery.

Will my landline work in a power cut?

That depends on the kind of line you have.

UK: landlines are moving to digital, and Ofcom counts a digital landline among your home broadband services. It says digital landlines need mains electricity and will not work in a power cut unless there is a battery back-up.

If you depend on your landline, your provider must make sure you can contact the emergency services during a power cut. If you don't have a working mobile phone or a reliable mobile signal, your landline provider must offer you a free back-up solution, such as a battery back-up unit. Ofcom says it must last at least one hour in a power cut, and some providers' back-ups last up to seven hours. If you aren't eligible for a free one, you can buy one from your provider or a retailer.

  1. Ask your provider whether your line has moved to digital.
  2. Tell your provider if you rely on your landline and don't have a working mobile or reliable mobile signal.
  3. If you use a care alarm, health pendant or other telecare device on your phone line, tell your provider before your line moves to digital. Ofcom says these may not work properly on a digital landline.

US: the FCC says to know which kind of phone service you have. Phone service over broadband, such as VoIP, will not work during electric outages without a battery or other backup power source. Traditional landline service, typically powered over copper lines, may work in an outage, though you may need a corded phone, because many cordless phones rely on electric power.

Providers that run home phone service over their own network, where the line doesn't carry power, must offer to sell you at least one backup option giving 24 hours of standby power for the equipment in your home. The FCC reminded providers of this rule, which applied from 13 February 2019. Ready.gov suggests finding out whether your home phone will work in a power outage and how long its battery backup will last. If you have a battery, the FCC says to test it from time to time, understand how long it should last, learn how to replace it, and consider a spare.

Can I call 999 or 911 in a power cut?

Yes, from a charged mobile phone, in most places.

UK: Ofcom says that for most people a mobile phone is a practical alternative when the power goes out. Even with no signal on your usual network, calling 999 will automatically connect through another network if one is available. Your phone shows this as "emergency calls only" on Android or "SOS only" on iPhone. Calling 999 or 112 is always free and works even without credit. Some phones can also contact the emergency services by satellite, using Emergency SOS on iPhone or Satellite SOS on Android, when no mobile network is available.

A digital landline needs power to make any call, 999 included. Ofcom's rule is that if you depend on your landline, your provider must make sure you can contact the emergency services during a power cut, with the free back-up above if you have no working mobile or reliable signal.

US: the FCC warns that VoIP service may not work during a power outage or when your internet connection fails. It suggests a backup power supply, keeping a traditional phone line, or having a mobile phone as a backup. Call 911 only for emergencies. You can text 911 in some areas, so the FCC says to check availability ahead of time.

Does mobile data work in a power cut?

Often, yes. Ofcom says that for most people a mobile phone is a practical alternative when the power goes out. It also notes that severe weather can cause service outages, that extreme heat and floods can damage mobile masts, and that mobile networks may get extremely busy.

When calls won't connect:

  1. Send a text. Ofcom says a standard text may get through even when the network is very busy. The FCC says the same.
  2. Wait between call attempts. Ofcom suggests waiting 20 seconds between attempts; the FCC suggests 10 seconds. Redialling quickly adds to the congestion.
  3. Use Wi-Fi calling if you have broadband. Ofcom suggests turning on Wi-Fi calling so calls can go over your broadband when the mobile network is down. That only helps if your broadband is still running, for example on backup power, or you're somewhere else that has power.

How do I keep my phone going in a power cut?

Charge it before the power goes, if you get any warning. Ofcom suggests charging your devices before any extreme weather the Met Office warns about, and keeping a battery power bank to recharge them if it lasts a long time.

Once the power is out, lower your screen brightness and turn on battery saver mode, as Ofcom recommends. If there's no signal at all, the FCC says turning the phone off stops the battery draining while it searches for one. Keep calls short: the FCC says limiting calls also conserves battery. There's more in how to charge your phone during a power cut.

Can I keep my broadband running in a power cut?

Only with a power source that isn't the mains. Ask your broadband provider what it offers for your equipment; in the UK, a provider must offer a free back-up to landline-dependent customers who don't have a working mobile or reliable signal.

If your broadband often goes down, Ofcom says you might consider satellite internet as a backup, especially in a rural or remote area.

More questions

Can I call 999 with no signal on my network?

Yes, if another network is available. Ofcom says calling 999 automatically connects through another network when yours has no signal. Your phone shows "emergency calls only" on Android or "SOS only" on iPhone. Calls to 999 or 112 are free and work without credit.

Do cordless phones work in a power cut?

Usually not. The FCC says cordless phones usually won't work in a power outage, and suggests keeping at least one corded phone that doesn't depend on electricity. That applies to a traditional landline. In the UK, a digital landline also needs mains power unless it has a battery back-up.

Will Wi-Fi calling work in a power cut?

Only if your broadband is still on. Wi-Fi calling sends calls over your broadband connection, and Ofcom says home broadband won't work in a power cut without an additional power source. Use your mobile network for calls and texts instead.

What should I do if my broadband is still down after the power returns?

Report it to your provider. Ofcom says most providers take reports by phone, online, live chat or app. If your provider is in Ofcom's automatic compensation scheme and your broadband or landline isn't fixed within two working days, you may be entitled to compensation.

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