Data SIMs, sorted.

The router gets all the attention. It's the shiny box, it has aerials, people argue about it in Facebook groups. But the little bit of plastic inside it decides which masts you can reach and what you pay every month for years to come. It even decides whether you're allowed to use the router at all.

Get the SIM wrong and a £340 router is a very expensive paperweight. Get it right and a £13 plan does the job for most people.

This guide goes deeper than the SIM section of our motorhome WiFi guide. If you haven't picked a router yet, start there, or let Sort my WiFi pick one for you.

The short answer

1. For most people: SMARTY 40 GB Data Only, £13 a month. No contract, allowed in a router, 12 GB to use in Europe, and you can pause it when the van's in storage.
2. If you stream on the TV most nights: SMARTY Unlimited Data Only, £20 a month. Same terms, no data limit to worry about.*
3. If you only tour now and then: Three's 120 GB data SIM, £40 for twelve months. About £3.33 a month. Buy it, forget about it, use it whenever you're out.
4. If EE has the best signal where you tour: an EE data SIM. Dearer, but EE tops the independent reliability tests.
5. The cheapest unlimited we've found, if you never leave the UK: a prepaid EE SIM from Scancom, sometimes discounted with a voucher code listed on HotUKDeals. It's sold to sole traders and businesses, it's what's in our router, and there's a whole section on it below because it comes with conditions.

*Pay attention to each network's fair use policy, because "unlimited" doesn't actually mean unlimited. There's more on that further down.

30 seconds on the words

Mobile networks have a language all of their own, and it isn't always designed to help. Here's the translation.

Which network?

This is the question that starts the arguments, so let's be honest about what the evidence says and what it doesn't.

The independent tests favour EE. RootMetrics tested all four in the first half of 2026 and put EE top overall, ahead of Three, Vodafone and O2 in that order. Opensignal's January 2026 report gave EE its awards for reliability and speed. The catch is that RootMetrics mostly tests in and around cities, and a lay-by in the Highlands is not a city.

Nobody publishes a clear countryside winner. Ofcom, the regulator, measures coverage across the whole country. In January 2026, 84% of the UK's land had good 4G from all four networks, and 96% from at least one. Read those two numbers together: across a big chunk of the countryside, at least one network works and at least one doesn't. Which one depends on exactly where you're parked. Ofcom also noted the biggest recent rural improvements were on Vodafone and Three, as their masts get joined up.

Our own experience matches the tests, mostly. I think EE is the best network for touring, and it's what's in our router. But plenty of people tour happily on SMARTY (which uses the VodafoneThree network) and never have a problem, and I've been parked at Semer Water in the Yorkshire Dales with the router and Claire's phone (both on EE) showing nothing at all, while my Lebara phone (on Vodafone) had a signal. So no network is always best. Which is the whole point of the next section.

What to actually do: put the postcodes of the places you stop into Ofcom's coverage checker. It shows all four networks side by side. Look at the outdoor prediction if you've got, or are thinking of fitting, a roof aerial, because the aerial is outside the van. Look at the indoor one if your router sits inside.

Three networks, lots of brands

Vodafone and Three merged in 2025 to form VodafoneThree. Their masts are being joined up so that a SIM from either side uses whichever mast is stronger. By April 2026 that was switched on at 10,000 mast sites, and Vodafone expects it to be finished in the early 2030s. So in more and more places, Three, Vodafone and all their brands are the same signal.

Brands do move networks from time to time (Lyca moved from O2 to EE, for example), so check the network before you buy, not after.

Two networks are better than one

If your WiFi really matters, the single best thing you can do has nothing to do with which router you buy. It's making sure you've got two different networks in the van.

The cheapest way is free: put the router SIM on one network and make sure at least one of your phones is on a different one. When the router has nothing, switch the laptop or TV over to the phone's hotspot. That's exactly what saved us in the Yorkshire Dales.

The rule is simple: pick your two from different columns in the table above. A SMARTY data SIM in your router and a Vodafone SIM in your mobile phone look like two different networks, but they're not. A SMARTY data SIM in your router and a phone SIM on EE or giffgaff really are two different networks.

If you'd rather the router handled it for you, some routers (including the GL.iNet Spitz AX) take two SIMs. Put one from each column in. Two slots usually means the router swaps between them rather than using both at once, so check how yours switches before you rely on it.

The WiFi guide has more on this in check your second SIM is on a different network.

Which plan?

Here are the ones worth looking at. We've kept it short on purpose: these are the plans that say in writing you can use them in a router, and that suit touring.

Prices and terms change. We check them every week, but always look at the plan page again before you pay.

Why SMARTY is our pick for most people

SMARTY isn't the strongest network, and we won't pretend otherwise. What it has is every box a tourer needs ticked at once. It's cheap. It says in its terms, in black and white, that it can go in a "portable mobile WiFi device". It includes 12 GB of data in Europe. There's no contract, and you can pause it between trips without ringing anyone. Plenty of plans do two or three of those things. SMARTY does all of them.

SMARTY also has smaller and bigger tiers if 40 GB isn't right: 15 GB for £9 and 100 GB for £17, all on the same terms.

How much data do you need?

We did the sums properly in the WiFi guide, but the short version is that video is what eats your data. Everything else barely registers.

One HD film is about 3 GB an hour. A night of HD telly is 6 GB, so a fortnight of it is around 90 GB. And one phone quietly backing up a ten-minute 4K holiday video can use more data than half an hour of Netflix, so turn off automatic photo backup over mobile data on every phone and tablet in the van.

"Unlimited" is nearly unlimited

Every unlimited plan has a fair use limit somewhere. EE's is 600 GB a month, after which they may slow you down at busy masts. Scancom's EE SIM says 650 GB a month, after which the service may be suspended. SMARTY and Three don't give a figure, but say heavy users may be slowed when a mast is busy.

For scale, 600 GB is about 200 hours of HD Netflix, or nearly seven hours every single day. You won't hit it in a van unless you're doing something very unusual. What's worth knowing is what happens if you do: being slowed down is a nuisance, being suspended is a much bigger deal.

Will it work in a router?

This is the bit that catches careful people out, because the networks draw a line between using data in a phone and using it in anything else.

The trap: home broadband SIMs

Every network sells "4G home broadband": a router plus a SIM, often at a tempting monthly price. Don't be tempted. These are tied to the address you give when you buy. Three's terms, for example, say the equipment is for "use in your home at the address you have provided" and that roaming doesn't apply. Great for a static caravan on one site, wrong for touring.

The same goes for living in the van full-time. SMARTY, like most providers, says its data SIMs shouldn't be used as a permanent replacement for home broadband. Touring is exactly what they're for. Moving into the van for good is more of a grey area (although how they'd ever know you'd sold the house is anyone's guess).

Stop paying between trips

If the van spends the winter in storage, there's no reason to pay for a SIM that's sitting in a cupboard. How easy that is depends entirely on the plan you pick, which is one of the biggest reasons we recommend what we do.

What it's worth. Tour April to September on SMARTY 40 GB and you pay £78 for the year instead of £156. On EE's 24-month Unlimited No Frills plan, the price starts at £27 a month and is scheduled to rise to £28.50 from 31 March 2027 and £30 from 31 March 2028, so compare the full term rather than multiplying the launch price by 24 whatever the van did.

Don't let your SIM go to sleep

Here's the trap nobody mentions. Leave an ordinary SIM in the router all winter without using it and it may be dead by spring. Every provider cuts off SIMs that go unused for long enough, and the number of days varies wildly.

The easy fix. Put a reminder in your phone for every three months while the van's laid up. When it goes off, power the router on for ten minutes and use a bit of data, or buy the cheapest plan. On SMARTY that's the 2 GB plan for £5, once, sometime in the spring. A £5 insurance policy against starting the season with a dead SIM.

If the worst happens, a data SIM's number doesn't matter, so you can just order a new SIM. The cost is nothing. The delay is what hurts, especially if you find out on the first night of your first trip.

Taking it to Europe

Since Brexit, free roaming in Europe is no longer guaranteed by law. Each plan sets its own rules, and two numbers matter: how much data you can use abroad, and how long you can stay.

For a fortnight in France, SMARTY's 12 GB is enough for maps, email and a few video calls, but not for streaming every night. For longer trips, or anything over about two months, a local SIM or a European eSIM bought when you arrive is usually cheaper and avoids the time limits altogether. Our WiFi in Europe guide has the detail.

Buying as a business: the Scancom deal

This is what's actually in our router, so it seems only fair to explain it properly.

Scancom sells prepaid data SIMs on EE's network. You pay once and get unlimited UK data, up to a 650 GB fair use limit, until a fixed end date. You can have it as a physical SIM or an eSIM. At full price, the one running to March 2028 was £299.99 when we checked, which is about £17 a month for unlimited data on EE, compared with £30 a month and up from EE themselves.

Voucher codes for Scancom sometimes appear on HotUKDeals. We paid £197 for ours in June 2026, which is £9.38 a month over 21 months, because the end date is fixed and we bought earlier. Search Scancom on HotUKDeals before you buy. Codes come and go, so check the seller price and expiry before deciding.

Scancom sells Three-network versions too, and some of those deals are even cheaper. They come with the same conditions.

Who can buy it. Scancom's page says it's for sole traders and businesses, and adds: "Individuals are registered as sole traders." So you don't need to be a limited company. If you're self-employed, you're already exactly who it's aimed at.

The conditions, and they matter:

1. UK only. There's no roaming at all. It's no use the moment you're on the ferry.
2. The clock always runs. You can't pause it, so winter months count whether the van moves or not. Work out the monthly cost over the months you'll actually use it.
3. You're buying as a business. That means fewer of the rights a normal consumer gets. Scancom's terms say there's no refund once the pack has been opened or the SIM used.
4. No app or account. There's no way to see how much data you've used, so we rely on the counter in the router. Worth knowing with a fair use limit in the terms.
5. No extensions. When it ends, you buy a new one.

If you're self-employed, UK-based and stream a lot, it's very hard to beat. If you head to Europe, or the van's laid up half the year, SMARTY will probably work out better value. Pair it with a phone on a different network and you've got the best of both, which is exactly what we do.

Before you buy: a quick check

1. Check coverage at your favourite sites and overnight stops. Put their postcodes into Ofcom's coverage checker.
2. Pick a different network from your phone. Different columns in the network table.
3. Check it's allowed in a router. To stay on the right side of the network's terms, it's best to stick to plans in the "Yes, in writing" box. But that decision is yours.
4. Check the SIM size your router takes. The GL.iNet Spitz AX takes two nano SIMs. The Teltonika RUT241 (also inside the Maxview Roam) takes a standard mini SIM. Most SIMs now come as "triple cut", so you pop out whichever size you need.
5. Check your router isn't locked. The UK ban on network-locked devices only covers mobile phones, so a router bought from a network (such as Three's or EE's own) can still be locked to that network. Ones from Solwise, GL.iNet, Amazon and most other shops aren't.
6. Check whether you can pause it. If the van goes into storage for several months over winter, this is worth more than any headline price.
7. Heading abroad? Check the roaming allowance and the time limit.
8. Check the price again on the provider's own page, on the day you buy.

Setting it up

Most of the time you put the SIM in, switch the router on and it just works. If it doesn't, it's almost always one of three things.

1. The SIM PIN. Put the new SIM in a phone first, and turn off the SIM PIN lock in the phone's settings. Otherwise the router can refuse to connect every time it restarts.

2. Switch off before you swap. Turn the router off before you put the SIM in or take it out. Some routers don't like having it swapped while they're running.

3. The APN. If the router still won't connect, it may need the APN typing in by hand. It's in the router's mobile or cellular settings.

Give it a couple of minutes after changing the APN, then restart the router. Then run the 10-minute test to see what your download and upload speeds are really like.

What we run

In the Spitz AX: a Scancom prepaid EE SIM, unlimited, running until March 2028. In our pockets: Claire's phone on 1pMobile, which is EE again, and mine on Lebara, which is Vodafone. That's our two networks from two different columns.

If I were starting from scratch and went abroad even once a year, I'd put SMARTY in the router and keep a phone on EE. That's the setup we recommend to most people, and it costs £13 a month.

So, what now?

1. Haven't got a router yet? Answer a few questions in Sort my WiFi and it'll recommend one, including the SIM.
2. Not sure what your signal's really like? Do the 10-minute test first. It's free and tells you whether you need to spend anything at all.
3. Ready to buy? SMARTY 40 GB Data Only for most people, SMARTY Unlimited if you stream every night.