Fit it yourself
How LineKeeper works
Three steps, about 60 seconds, and no engineer.
On this page
Step 1: Unplug
Pull the power lead out of the back of your broadband hub. That's the only lead you touch. Your phone and internet cables stay exactly where they are.
What you'll see: the hub's lights go off — that's fine, they'll be back in a moment. The power plug is usually round, and the label on it almost always says 12V. If yours says something else, check the compatibility guide before going further.
Step 2: Click
Plug that lead into LineKeeper, then plug LineKeeper's lead into the hub. The hub boots up as normal. On full fibre with a separate white Openreach box on the wall, use the splitter lead in the box so 1 LineKeeper feeds both.
What you'll see: the hub's lights come back on within a minute or two, and LineKeeper's own lights show it charging. There's nothing to switch on and no app to install.
If it doesn't fit: the plug sizes cover the hubs used by BT, EE, Sky, Virgin Media, TalkTalk, Plusnet and Vodafone. If yours is the rare exception, the 90-day money-back guarantee covers you.
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Step 3: Forget
LineKeeper charges itself and waits. When the mains fails it takes over in the same instant (zero-second handover), so the hub never restarts and calls don't drop. When the power returns, it hands back and recharges.
That's the whole job. There's no maintenance schedule, no subscription and nothing to remember — beyond a quick test twice a year, which takes less than a minute.
What LineKeeper actually does
Your hub is a small computer. Like any computer, if it loses power it has to restart — and a hub restart takes 2 to 5 minutes. During that time your landline is dead, your Wi-Fi is down, and anything that calls out through the line, like a pendant alarm, can't get through.
LineKeeper is a battery that sits in the power lead and watches the mains. The moment the mains voltage drops, it switches the hub to battery power so fast the hub never notices. No restart, no dropped call, no gap in the alarm line. When the mains comes back, it switches back and tops itself up.
Because the switchover is instant, everything connected to the hub carries on: the dial tone on a corded phone, the Wi-Fi your tablet uses, and the line your telecare or pendant alarm calls through.
What happens in a power cut
- 0 seconds: the hub stays on. Dial tone, Wi-Fi and the line your pendant alarm calls through all carry on.
- Hour 1: this is where a battery built to the legal minimum runs flat. LineKeeper is barely a quarter used.
- Hour 4 and on: still connected. You've reported the fault, checked on family and heard the news.
If a cut does happen, call 105 free to report it and get updates — the line will be working, which is rather the point.
Which hubs it fits
LineKeeper fits any UK broadband hub whose power plug says 12V — which is almost all of them. That covers the current hubs from BT, EE, Sky, Virgin Media, TalkTalk, Plusnet and Vodafone, including full-fibre setups with a separate Openreach box on the wall.
We keep a guide for each provider with the exact hub models and any quirks:
- BT hub battery backup
- EE hub battery backup
- Sky hub battery backup
- Virgin Media hub battery backup
- TalkTalk hub battery backup
- Plusnet hub battery backup
- Vodafone hub battery backup
LineKeeper vs the battery your provider offers
Under Ofcom guidance, providers must offer a backup solution to customers who depend on their landline — but it only has to last 1 hour. Many provider units are built to exactly that minimum, and some come with a monthly fee or a contract tie-in.
| LineKeeper | Typical provider battery | |
|---|---|---|
| Backup time | 4+ hours | 1 hour (the minimum) |
| Cost | One-off, from £89 | Sometimes a monthly fee |
| Fitting | 60 seconds, yourself | Often an engineer visit |
| If you switch provider | Take it with you | Usually tied to the provider |
If your provider offers you a free unit that genuinely meets your needs, take it — we'd rather you were covered. LineKeeper is for people who want more than the 1-hour minimum, or who'd rather own their backup outright.
How long it lasts in a power cut
LineKeeper has a 74 Wh battery. A typical UK hub uses roughly 10 to 15 watts, which gives 4 hours or more. Powering a separate fibre box as well, or an older hub that draws more, shortens that.
| What LineKeeper is powering | Typical runtime |
|---|---|
| Modern broadband hub only | 4+ hours |
| Hub plus separate fibre box | Less than hub alone |
| Older or high-power hub | Less than 4 hours |
| Provider minimum (Ofcom guidance) | 1 hour |
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Looking after it
LineKeeper needs almost no looking after. Keep it plugged in so it stays charged, keep it somewhere dry and out of direct sun, and don't cover it — like any battery, it likes a bit of air.
Twice a year, do the fuse-box test below. It takes less than a minute and tells you the battery is still healthy. If the unit ever fails the test, get in touch and we'll sort it.
Test it yourself
After fitting, switch off the power at the fuse box and pick up a corded phone plugged into the hub. You should hear a dial tone straight away, and the hub's lights should stay on. Switch the fuse box back on, and LineKeeper recharges itself.
If there's no dial tone, check the leads are clicked fully in — and if it still isn't right, the 90-day money-back guarantee covers you.
Related guides
Helpful answers
Frequently asked questions
Answers about fitting, full fibre, cordless phones and what happens when the electricity goes off.
Do I need an engineer to fit LineKeeper?
No. Fitting takes about 60 seconds: move the hub's power lead into LineKeeper, then plug LineKeeper's lead into the hub. No app, no settings, no tools.
Does it work with full fibre (FTTP)?
Yes. If you have a separate white Openreach box on the wall, use the splitter lead in the box so 1 LineKeeper powers both the hub and the fibre box.
Will my cordless phone work in a power cut?
Cordless phone bases need mains power, so they go off in a cut. Keep 1 corded phone plugged into the hub's phone socket — corded phones draw power from the line and keep working.
What happens when the power comes back on?
LineKeeper hands back to the mains automatically and recharges itself. You don't need to do anything.
What if I move house or change provider?
Unplug it and take it with you. It works with any UK hub whose power plug says 12V, which covers BT, EE, Sky, Virgin Media, TalkTalk, Plusnet and Vodafone hubs.
Does it power anything else, like a TV or laptop?
No. LineKeeper is made only for broadband hubs and fibre boxes. That's what lets a small, safe battery last 4 hours or more.
How do I know it's charged and ready?
It charges itself whenever it's plugged in. The lights on the unit show the charge level. Test it twice a year by switching the socket off at the wall.
What if it doesn't fit my hub?
Check the label on your hub's power plug — if it says 12V, it fits. If it doesn't, or you're not happy for any reason, the 90-day money-back guarantee covers a full refund.
Keep your line on through the next power cut
From £89 (was £178). Free tracked UK delivery, 90-day money-back, fits in 60 seconds.
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