Buying guide
An alternative to the BT battery backup unit
If you're not eligible for a free unit from BT, or you want longer than the 1-hour minimum, here's how the options compare.
On this page
Who gets a free BT unit
Customers who depend on their landline, for example with a telecare alarm or no mobile signal, can ask for a free solution. Others are usually asked to pay. Contact BT directly to check.
Runtime matters
Provider solutions are built to give at least 1 hour. LineKeeper's 74 Wh battery gives 4+ hours on a typical hub.
LineKeeper™ Hub Battery Backup
4+ hours of backup · fits in 60 seconds · free UK delivery · 90-day money-back
From £89
Works across providers
If you ever switch from BT, LineKeeper still works with EE, Sky, Virgin Media, TalkTalk, Plusnet, Vodafone and other 12V hubs.
Quick comparison
Provider solutions differ, so check BT's current offer for exact details.
| Provider solution | LineKeeper | |
|---|---|---|
| Cost | Free if eligible | From £89 |
| Minimum runtime | 1 hour | 4+ hours typical |
| Works if you switch provider | Check with provider | Yes, any 12V hub |
| Guarantee | Provider terms | 90-day money-back |
How long will the backup last?
LineKeeper has a 74 Wh battery. A typical UK broadband 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 uses more power, shortens that. Fewer connected devices make it last longer.
For comparison, providers only have to offer a solution that lasts at least 1 hour. Many UK power cuts, especially in storms, last longer than 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 |
Is LineKeeper right for your home?
It's a good fit if: your phone now plugs into your broadband hub; someone at home relies on the landline or a pendant alarm; mobile signal is weak where you live; or you buy for a parent who lives alone.
It's not the right fit if: your hub's plug label doesn't say 12V; you need to power a computer, TV or fridge (LineKeeper is made only for hubs and fibre boxes); or your alarm already has its own mobile (SIM) connection and you don't use the landline.
Not sure? Try it for up to 90 days. If it doesn't suit you, send it back for a full refund.
How to fit it, step by step
- Charge it. Plug LineKeeper into the mains and let it charge fully. It stays plugged in from then on.
- Check the plug label. Look at the label on your hub's power plug. If it says 12V, LineKeeper fits.
- Connect the hub. Unplug the hub's power lead from the hub, plug it into LineKeeper, then plug LineKeeper's output lead into the hub.
- Add the fibre box if you have one. If a separate white Openreach box on the wall also has a power lead, use the splitter lead in the box to power both.
- Plug in a corded phone. Keep 1 corded phone plugged into the hub's phone socket. Cordless bases need mains power, corded phones don't.
- Test it. Switch the socket off at the wall. The hub lights should stay on and you should still get a dial tone.
LineKeeper™ Hub Battery Backup
4+ hours of backup · fits in 60 seconds · free UK delivery · 90-day money-back
From £89
Sources and further help
How we write our guides
Written by the LineKeeper team in plain English. We check facts against Ofcom, Openreach and provider guidance, and update guides when the rules change. We sell the LineKeeper Hub Battery Backup, and we say when it isn't the right fit. About us.
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Helpful answers
Frequently asked questions
Straight answers to common questions about bt battery backup unit alternative.
Is LineKeeper made by BT?
No. LineKeeper is an independent product that works with BT hubs and other 12V UK broadband hubs.
Do I need an engineer to fit it?
No. Fitting takes about 60 seconds: move the hub's power lead into LineKeeper and plug LineKeeper into the hub. No app, no settings.
Is there a guarantee?
Yes. Every order has a 90-day money-back guarantee and free tracked UK delivery.
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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