Backup internet for UK homes and small businesses: every option, cost and set-up

BT Group plans to retire the UK's old analogue phone network by 31 January 2027. Once your landline is digital — and many already are — your home phone only works while your router has power. This guide matches each kind of failure to the cheapest backup that actually survives it, with costs, a step-by-step guide to automatic failover, and how to check that it works.

Which backup is right for you?

Answer up to five short questions. Each answer sends you to the cheapest option that handles your situation, with a link to the part of this guide that explains it. If you don't know an answer, say so: some questions can't be answered honestly without a quick check first.

Whatever you choose, none of these options works in a power cut unless every box in the chain — fibre box, router, backup router — has battery power.

Who needs backup internet

A useful test: what does a day offline cost you? If the answer is "nothing much", your phone is your backup. If it's lost earnings, missed sales or a safety risk, a proper backup may cost less than one bad day.

Remote and hybrid workers

If you're paid by the day or the client, an outage during working hours is lost income and lost goodwill. The minimum is a phone hotspot on a different network from your broadband. If you're on video calls most of the day, an automatic 4G/5G failover router means a dropped line becomes a short pause rather than a scramble.

Small businesses, card terminals and phones

Shops, cafés, salons and offices increasingly run everything — card payments, tills, booking systems, internet phones — over one broadband line. Some card terminals have a built-in mobile SIM and can carry on when your Wi-Fi drops; others rely entirely on your broadband. Check with your terminal provider which kind you have and whether it switches over automatically. For anything with staff and customers on site, automatic failover and a UPS are the baseline.

Rural homes

Long copper lines and overhead cables are more exposed to storms and faults, and repairs can take longer to reach remote areas. If your broadband is your only practical connection, a backup on a different medium — 4G/5G where signal allows, satellite where it doesn't — removes a lot of anxiety.

Telecare and alarm users after the switch to digital

Once your landline is digital, a telecare alarm that connects through the phone socket on your router needs that router to have power — and a working connection. Some digital telecare alarms have their own battery and mobile SIM and carry on regardless; others stop when the router does. And some automatic broadband backups don't carry phone calls at all: BT, for example, says its Digital Voice home phone doesn't work while its Hybrid Connect 4G backup is in use.

Ofcom's guidance says providers should offer customers who depend on their landline — for example, people with no mobile signal at home or who use telecare — a free solution that lets them call 999 for at least one hour in a power cut. That covers emergency calls, not your broadband or every device on the line. Providers that signed the government's telecare and landline charter have committed to go further where they can, and GOV.UK says battery back-up units typically last four to seven hours. If you or a relative depend on telecare:

• tell both the phone provider and the telecare provider, and ask exactly how the alarm connects;
• ask what happens in a power cut and in a broadband fault, and how long any backup lasts;
• after any change, test the alarm with the telecare provider, following its instructions.

We can't tell you whether a particular set-up is safe: only the providers involved can confirm that for your equipment.

Gamers and streamers

A backup connection will keep you online, but rarely at the latency you're used to. Treat it as a way to finish a match or keep a stream from dropping, not as a like-for-like replacement.

Landlords, HMOs and holiday lets

Tenants and guests now expect working Wi-Fi as much as hot water, and smart locks, heating controls and remote check-in all depend on it. An unattended property needs an automatic backup, plus alerts so you know when it has switched over.

What can fail — and what each failure takes out

A backup only helps if it doesn't fail for the same reason as your main line. That's the idea most guides skip, and the reason a second broadband line from the same street cabinet is often a poor backup.

The five failures to plan for:

1. A fault on your own line — a damaged cable, a faulty socket or a dead fibre box. Only your home is affected.
2. An area outage — a cabinet loses power, a fibre is cut by roadworks, an exchange has a problem. Your whole street or town may be affected, on that network.
3. A power cut at your home — your fibre box, router and digital phone all stop, even if the network outside is fine.
4. A wide-area power cut — after a storm, for example. Your home, the street cabinets and possibly nearby mobile masts lose power. Mobile masts have some battery backup, but how long it lasts varies: Ofcom's June 2026 resilience guidance sets expectations without a fixed number of hours.
5. A provider-wide outage — a fault in your provider's core network can take down customers across the country, whatever the physical line.

And one people forget: your own router fails. If your backup depends on the same box, it fails too.

Failure × backup: what survives what

This table shows how each technology is built, not results of our own tests. Phone calls, telecare and alarms need checking separately: an internet backup doesn't always carry them.

What this means in practice:

• Different provider beats different technology alone. A mobile backup from the same company — or the same group — as your broadband (for example BT broadband with EE mobile backup) may share some network systems, so it may not protect you from a fault affecting that provider's whole network.
• Power is the common weakness. Every option except phones and battery-powered mobile Wi-Fi needs a UPS to survive a power cut at home.
• Satellite is the only option that doesn't depend on local infrastructure in a wide-area power cut — provided you can power the dish, which draws far more than a router.

Every backup option, with pros and cons

Phone hotspot or tethering

Your phone shares its mobile data over Wi-Fi. Pros: free, instant, no extra kit, survives a power cut on battery. Cons: drains the phone, ties it up, and some plans limit how much data you can share — check yours; serves only a few devices well. Best for: occasional short outages, light use, a first line of defence. Make it more useful by choosing a phone plan on a different network from your broadband provider's mobile arm.

4G/5G mobile Wi-Fi (MiFi)

A pocket router with its own SIM and battery. Pros: keeps your phone free, portable, battery-powered, its own data allowance. Cons: you switch over by hand; small antennas; fewer devices. Best for: home workers who are usually present, travel, second homes.

4G/5G router with automatic failover

A router that watches your main line and switches to mobile data when it drops, then switches back when the line returns. Two ways to get one:

• Provider bundles. BT's Hybrid Connect adds an EE 4G backup to BT broadband and is included in BT Halo 3+. BT values it at £7 a month when bought separately; check the current price with BT before ordering, as third-party sites quote different figures. BT says switching to the 4G backup takes about two to three minutes, and once switched you stay on mobile for at least 15 minutes before it moves back; backup speeds are up to 30Mb download and 5Mb upload, depending on signal. BT also says Digital Voice calls don't work while you're on the 4G backup. BT's other Halo tiers offer a "Keep Connected" 4G mini hub, but it's posted to you after you report a fault, so it isn't automatic. Vodafone's Pro 2 broadband packages include a 4G broadband back-up with a 100GB monthly allowance. Bundles are simple, but may share the provider's network systems (see the table above).
• Standalone failover routers with a SIM slot, used with a data SIM on a network of your choice. More set-up, but you can pick a network unrelated to your broadband provider.

Pros: automatic, fast, cheap to run. Cons: needs good indoor signal; needs a UPS for power cuts; mobile data limits; may not carry your home phone. Best for: most home workers and small businesses with decent mobile signal.

Dual-WAN router (bring your own)

A router with two internet inputs, so your fibre box goes into one and a separate 4G/5G router (or a second line) into the other. Pros: the most flexible option; works with any combination of lines; can alert you when it switches. Cons: needs some confidence configuring a router; the dual-WAN router itself becomes the single point of failure. Best for: confident users, small offices, anyone combining fibre with satellite or a second line.

A second fixed line on a different network

Pros: full speed and unlimited data on backup; ideal for heavy users. Cons: a second monthly bill and installation; only resilient if it is genuinely separate — a different network operator and, ideally, a different route into the building. Two lines from the same cabinet or duct can fail together, and many addresses only have one full-fibre network. Best for: businesses and heavy home users where full fibre from two networks reaches the address. Our fixed broadband guide explains how to check which networks reach you.

Satellite as backup

Pros: independent of local cables and masts; works where mobile signal is poor. Cons: expensive as a full second line; high power draw; needs a clear view of the sky. Two ways to use it:

• Standby Mode keeps a Starlink dish connected at a very low speed (about 0.5Mbps) for a reduced monthly fee — reported at £9 a month since June 2026, up from £4.50. It isn't available on Starlink's newer V5 dish, so check your kit and the current price on Starlink's site. That should be enough for messages, email and other light use — test your card terminal on it before relying on it — but not for video calls.
• A full satellite plan as a true second line, connected to a dual-WAN router for automatic failover.

More in our guide to satellite broadband.

Bonded and load-balanced connections (business)

Bonding combines two or more connections so traffic flows over all of them at once; if one fails, the others carry on with no switch-over at all. Pros: seamless for internet calls and video; extra capacity day to day. Cons: usually a business service with set-up and monthly fees; still needs the underlying lines to be diverse. Best for: offices where every minute offline costs money.

Power backup for all of the above: the UPS

An uninterruptible power supply sits between the mains and your equipment and switches to battery when the power fails. To size one:

1. List everything in the chain that must stay on: fibre box (ONT), router, backup router, phone adapter, and any switch or mesh unit.
2. Add up their power draw in watts. The label or power adapter shows a maximum; a plug-in power meter shows what each device actually uses.
3. Estimate runtime as roughly the UPS's usable battery capacity in watt-hours divided by your total load in watts. As a rough illustration, a 20W load on a battery with 200Wh of usable capacity would last about 10 hours before losses — real runtime will be lower. Runtimes vary with battery age, temperature and load, so check your load against the manufacturer's runtime chart for the specific UPS, and test it.
4. Check the outputs: many small "router UPS" units provide 12V or USB outputs that match routers directly, which is more efficient than a mains-output UPS.

A satellite dish changes the sums entirely: Starlink's Standard kit typically draws 75–100W on average, so it needs a far larger battery. Check the specification for your model.

Don't rely on a runtime figure for safety. If someone depends on a telecare alarm or on being able to call 999, ask the phone and alarm providers what backup they provide and test the real set-up, rather than relying on a general estimate.

Costs compared

The cheapest backup is the one you already own. After that, costs rise with how automatic, how fast and how independent the backup is. We only show prices we could check on 8 November 2026; elsewhere, enter the quotes you get into the calculator below.

Compare the cost over 24 months

Compare what it costs to keep up to three backup options running. Prices you enter stay in this browser tab.

This tool needs JavaScript, which seems to be switched off or still loading. The guide around it explains the same steps in words.

Compare over1 to 60 monthsmonths

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Option A

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Option B

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Option C

Name (optional)

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One-off costsSet-up, installation, delivery£

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Router, dish or other equipment

Included or none Buy outright Rent monthly

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First rise fromMonth, as YYYY-MM

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Average power draw (optional)For electricity cost; leave empty to excludeW

Your own outage scenario (optional)

Only if you want to compare the cost of a backup with what outages might cost you. This is your estimate, not a saving we can promise.

Working days lost to outages a yeardays

What a lost day costs you£

How the calculator works

Each option’s total is the monthly price for every month in the period (promotional months at the promotional price), plus each price rise from its month onwards, plus one-off costs, plus equipment — either bought once or rented every month, never both — plus electricity if you give a power draw and a unit rate (watts × 24 hours × 30.4 days per month ÷ 1,000 × your rate). Amounts are worked out in pence. It doesn’t include early exit fees, credits, cashback or price changes not written into the contract. More in our methodology.

A quick way to decide what to spend: estimate how many working days you lost to outages last year and what each cost you. If a backup costs less over two years than that, it may be worth it — as long as it survives the kind of failure you actually had.

How to set up automatic failover, step by step

This is the general method for a home or small office. Exact menus differ by router, so follow your router maker's instructions for each step.

1. Map your chain. Write down every box between the wall and your devices: fibre box (ONT) or modem, main router, any phone adapter, mesh units, network switch. Note which plug each one uses.
2. Choose a backup that shares as little as possible with your main line — a different medium (mobile or satellite), a different network operator and, ideally, a different provider. Run the one-day 4G/5G test at the spot where the backup router will sit.
3. Pick your hardware route.
   • Your existing router supports failover (some have a SIM slot or accept a USB modem): enable it in the router's internet or WAN settings.
   • Add a dual-WAN router in front of everything: the fibre box goes into WAN1, the 4G/5G router into WAN2.
   • Use a provider bundle: follow the provider's set-up; it's usually plug-and-play with their router.
4. Put the 4G/5G router in bridge or passthrough mode if you're feeding it into a dual-WAN router and it supports this. That avoids two routers both handing out addresses ("double NAT"), which can upset internet calls and gaming.
5. Configure the failover rules.
   • Set the main line as primary and the backup as failover only (not load-balancing, unless you want both used at once).
   • Set health checks that test two independent, reliable internet addresses, so one site being down doesn't trigger a false switch.
   • Choose how many failed checks trigger a switch, and turn on automatic failback so traffic returns to the main line when it recovers.
   • Turn on alerts (email or app notification) for switch-over and switch-back.
6. Protect your data allowance. While on backup, pause cloud photo and file backups, games console downloads and operating-system updates. Some routers can block named services when on the backup link; otherwise, set usage alerts on the SIM.
7. Add power. Plug the fibre box, routers and phone adapter into a UPS, and check the manufacturer's runtime chart against your total load.
8. Check voice and special devices. Ask your providers whether phone calls, card terminals, alarms and telecare work over the backup path — some don't — and arrange a test with them.
9. Write a one-page note for everyone in the home or business: what the lights mean, how to tell you're on backup, who to call, and how to report a fault to your provider.

How to check your backup works

A backup you've never checked is a hope, not a plan. Check it after setting up, after any router firmware update, and then regularly. Do it at a quiet time, tell everyone in the home or business first, and never during a call or a busy trading period.

1. Disconnect the main line in a controlled way. Unplug the cable between the fibre box and the router (or the router's WAN cable). Note how long your devices take to come back online.
2. Keep something low-stakes running while you do it — a video stream, for example — and note whether it drops or just pauses.
3. Check power backup with care. If your UPS maker suggests a test, follow its instructions. Don't cut power to equipment that someone relies on for safety, such as a telecare hub, and don't make test calls to 999.
4. Check failback. Plug the main line back in and confirm traffic returns to it and the backup goes idle.
5. Check once in the evening. Mobile backup speeds are lowest at busy times; make sure it's still usable at 9pm.
6. Check data used on the backup SIM afterwards, so you know how quickly a real outage would eat your allowance.
7. Write down the results — date, switch-over time, any drops — so you notice if things get worse.

For telecare and alarm equipment, ask the provider how to test it: many have a test procedure that doesn't involve the emergency services.

Printable checklist: before your broadband fails

• I know which network my broadband uses, and my backup uses a different one.
• I know which devices must keep working: phone, telecare, alarms, card terminal, router.
• I've asked my phone and alarm providers how each device connects and what happens in a power cut and a broadband fault.
• I know whether my backup carries phone calls.
• Every box in the chain that needs mains power is on a UPS, and I've checked the manufacturer's runtime chart against my load.
• I've checked switch-over and switch-back at a quiet time, and written down the result.
• I know how to report a fault to my provider, and I keep the reference number.
• Everyone at home or at work knows how to tell when we're on backup.

Your rights during an outage

Automatic compensation (fixed broadband and landline)

If your provider has signed up to Ofcom's automatic compensation scheme, you're credited without having to ask — usually within 30 days. These were the rates on Ofcom's website in November 2026; they rise each year with inflation:

Ten providers are signed up: BT, EE, Hyperoptic, Plusnet, Sky (including NOW Broadband), TalkTalk (restrictions for customers not on the Openreach network), Utility Warehouse, Virgin Media, Vodafone and Zen Internet. The scheme covers residential fixed broadband and landline products, so mobile broadband, satellite and business lines are not included. The clock starts when you report the fault, so report it straight away and keep the reference.

Other rights worth knowing

• Complaints: if your provider hasn't resolved a complaint within six weeks, you can take it to a free dispute resolution scheme (the Communications Ombudsman or CISAS), under Ofcom rules in force since 8 April 2026.
• Persistent slow speeds: providers that follow Ofcom's Broadband Speeds Code of Practice must let you leave without penalty if your speed stays below the minimum guaranteed level and they can't fix it within 30 days.
• Small businesses: if no more than 10 people work for you, Ofcom's rules give you many of the same protections as households — including a contract summary, a 24-month maximum contract and access to a free dispute resolution scheme — but automatic compensation doesn't apply to business lines. Check your contract for any service-level agreement with faster repair times.
• Power-cut protection for landline users: if you depend on your landline and can't use a mobile (for example, no signal, or you use telecare), Ofcom's guidance says your provider should offer a free solution that lets you call 999 for at least one hour during a power cut. Ask your provider what it offers.

Frequently asked questions

What is the best backup internet for home?

It depends on what you need to keep working. For most homes, a phone hotspot or a cheap 4G/5G router on a different mobile network covers short outages. Remote workers and small businesses should consider a router with automatic failover, plus a UPS if it must work in a power cut.

Will my broadband work in a power cut?

No. Your fibre box and router need mains power, and once your landline is digital your home phone does too. A small uninterruptible power supply (UPS) can keep them running for a while. If you depend on your landline, ask your provider about the free solution Ofcom's guidance says it should offer for calling 999 for at least one hour.

Can I use my phone as backup internet?

Yes — it's the simplest backup there is. It works best on a different network from your broadband, for short outages and a few devices. It drains your battery and some plans limit how much data you can share.

What is automatic failover and how does it work?

Automatic failover means a router detects that your main broadband has dropped and switches traffic to a backup connection, usually 4G or 5G, within seconds to minutes depending on the router and settings. When the main line returns, it switches back. You need a dual-WAN or failover-capable router and a backup data plan.

Is a second broadband line worth it?

Only if it's genuinely separate — a different network operator and ideally a different route into the building — and you need full speed during outages. For most homes, a 4G/5G backup is far cheaper and covers most failures.

Can Starlink be used as a backup connection?

Yes. Standby Mode keeps a dish connected at about 0.5Mbps for a reduced monthly fee — enough for messages and email — though it isn't available on the newer V5 dish. A full plan works as a true second line with a dual-WAN router. Either way, the dish needs plenty of power in a power cut.

How much does a 4G backup router cost to run?

The running cost is mainly the data SIM — often modest if you only use it during outages — plus a little electricity. A 10W device running all the time uses about 88kWh a year, roughly £23 at the October–December 2026 price cap average of 26.32p per kWh. BT values its Hybrid Connect add-on at £7 a month where it isn't already included.

Do I get compensation when my broadband goes down?

If your provider is in Ofcom's automatic compensation scheme and your service is completely lost, you get £10.34 for each day it stays unfixed after two full working days. The scheme covers residential fixed broadband and landlines only, not mobile, satellite or business lines.

How do I keep my card machine working if the internet goes down?

First check whether your terminal has a built-in SIM that takes over automatically. If not, put your broadband on a router with automatic 4G/5G failover and a UPS, so the terminal has a connection when the line drops. Check it works at a quiet time, not on a busy day.

Will my telecare alarm work in a power cut after the digital switchover?

It depends on your equipment. Some digital telecare alarms have their own battery and mobile SIM and keep working; others connect through your router's phone socket and stop when the router loses power. Ask your telecare and phone providers how your alarm connects, what happens in a power cut or broadband fault, and how long any backup lasts — then arrange a test with them.

How we checked this guide

Product terms, prices and regulatory rules were checked against providers' own pages, Ofcom, GOV.UK, Ofgem and router and UPS manufacturers on 8 November 2026. Where only a secondary source was available — for example, for some Starlink prices — we say so. We have not tested routers, UPS units or failover set-ups ourselves; the failure table describes how each technology is built. More detail is in our methodology.

Sources

• Ofcom — Automatic compensation: what you need to know
• Ofcom — Quicker complaints resolution (six-week rule)
• Ofcom — Broadband speeds Code of Practice
• Ofcom — Protecting access to emergency organisations when there is a power cut (guidance, 2018)
• Ofcom — General Conditions: rights for businesses
• GOV.UK — UK transition from analogue to digital landlines
• GOV.UK — Public Switched Telephone Network charter
• GOV.UK — Ensuring telecom services are resilient
• ISPreview — Ofcom updates guidance on mobile power backup (June 2026)
• Openreach — PSTN switch-off update
• BT — Halo (Hybrid Connect)
• BT — Hybrid Connect terms
• BT — Broadband Backup for Halo customers
• BT — Will Digital Voice work in a power cut?
• Vodafone — Pro broadband
• DrayTek — Connection detection for failover
• APC — Back-UPS Connect 12V DC mini UPS for routers
• Ofgem — Energy price cap, 1 October to 31 December 2026
• Starlink — Specifications
• ISPreview — Starlink Standby Mode replaces free pause (August 2025)
• ISPreview — Starlink price rises, including Standby Mode (May 2026)
• ISPreview — No Standby Mode on Starlink's V5 dish (August 2026)
• ISPreview — Starlink area-based pricing (October 2026)