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Sky Mobile vs Three: comparing their 4G/5G networks & benefits

Sky and Three logos with a versus symbol

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We see if you're better off joining Three or Sky Mobile on a SIM only deal or phone contract and compare coverage, speeds and other features. SIM Sherpa is your trusty guide. Last updated: 20th August 2020.

In our Sky Mobile vs Three guide

Latest offers

Three and Sky Mobile's networks

Do Sky Mobile or Three have better coverage?

We look at which has the biggest 3G/4G/5G network

Mobile signal bars with Three and Sky logos

Sky have the better blend of coverage

Sky Mobile and Telefonica logos


See press release

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Three own and operate their own network. Sky Mobile are part of Sky and have an arrangement with O2 to use theirs. We think there's pros and cons to both Three and O2 in terms of coverage:

There's no real doubt Sky have the advantage for basic calls and texts. Indoor signal is generally better on Sky and there's fewer blackspots in ultra-rural areas too - they have more physical landmass covered.

For 4G data coverage, we'd say it's advantage to Sky again. But it's not so cut and dry. In larger towns and cities, there's little difference. It's only again rural 4G and smaller towns where gaps between them appear.

The main thing is to think about where and how you use your phone, then check each network's coverage using their official maps below to see what they offer in the areas you'll use them.

Useful link: More about Sky's network

5G is in its early days on both still

Three branded map of the UK with 5G pointers

Read latest 5G news

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It's still early days for 5G coverage on any network in the UK but the faster, higher capacity data service is live on both Three and Sky Mobile - so they're both viable choices for early adopters.

5G is very much still on a city-by-city basis, rather than nationwide. Three have it in the 192 places listed here, while Sky have it in these 150+ locations. There's some overlap but they have focused on different places too.

Here's the best value 5G deal from each provider currently:

On both Sky and Three, it's not like saying they have 5G somewhere means the whole place is covered. It's just the busiest areas that need a capacity upgrade that they've rolled out 5G into (check street-by-street here).

It's easiest to get 5G in your plan on Three. All their SIM only plans and phone contracts for 5G models include 5G at no extra cost. While on Sky, you have to be a Sky VIP member to get it free, or pay £5 extra a month.

Useful link: How to get 5G on Sky Mobile

Sky and Three network maps

Check everywhere you'll use your phone, not just at home

Sky coverage checker

Sky Mobile map

Check Sky signal

using their official map
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Three coverage checker

Three network map

Check Three signal

using their official map
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Our verdict on coverage:

Minor win for Sky Mobile

"Though Three have 5G in more places and are about even with Sky Mobile in larger towns and cities, we think Sky Mobile offer more reliable calls and data as you move round the country."

Compare pricing and deals

5G/4G data speeds on Sky vs Three

Which provider has faster data?

Speedometer icon with Sky and Three logos

4G on Three measures up faster than Sky

Hello 5G banner

How 5G will help

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To decide which networks are fastest, we look at speed test data collected by independent testers Opensignal and Speedtest by Ookla, who take millions of measurements around the country on volunteers' smartphones.

For years they've consistently said that Three's 4G downloads are faster than Sky's host network O2 (and our own tests find there's no difference between Sky vs O2). Here's how they compare:

On Three, customers typically received 4G download speeds around 20.39 Mbps and 22.4 Mbps. Via the O2 network, it's between 16.95 Mbps and 18.0 Mbps - in real life you'll get both higher and lower than these.

If you're a basic data user and just want to check emails and social media and browse a bit, both providers could be suitable. For streaming and big downloads, Three could be a better choice.

Useful link: What Three say about their network

5G speeds should be faster on Three than Sky

Three's fastest 5G network banner

Read why

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While Opensignal and Ookla have been measuring 4G speeds for years, there's not a huge amount of real-life test data for the speeds you'll get on each UK network's 5G.

Speedtest's blog has some early results before Three's 5G network was live, which put typical 5G downloads over the O2 network Sky use at 130.04 Mbps (289.65 Mbps peak) - so a massive improvement on their 4G.

From Three's own marketing, they're expecting to be the fastest UK 5G network, on the basis that they've secured the most spectrum on the best frequencies for speed and capacity.

Once there's more testing data on 5G, we can provide a more accurate picture. But for now we'd bet on Three's 5G being faster than Sky's via O2.

Useful link: Our guide to the best 5G networks

Our verdict on data speeds:

Win for Three

"If you know you're going to use your phone for more than just checking emails and browsing, the independent testers point towards Three being the better choice to avoid frustration."

Compare pricing and deals

Extra network features on Sky vs Three

Who has better extras to keep you connected?

WiFi calling icon and Sky and Three logos

Both Sky and Three have WiFi calling

Three WiFi calling banner

Check phone support

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WiFi calling lets your phone connect to a mobile network over WiFi instead of mobile signal, to make and take calls if you're somewhere that regular phone reception can't reach. Both networks offer this facility.

Out of the two we'd say Three's is the better scheme. It's been around longer so supports more phone models (our testing found it works with more phones than Three actually list here). And it can send/receive SMS texts.

Sky Mobile's WiFi calling is less settled. The list of supported devices is smaller, it doesn't support SMS and we find you can't switch between a WiFi call and a 4G call without it dropping.

As long as your phone's supported either network is an option, it's just you've got a better chance with Three. It's worth noting that Sky's regular mobile signal is generally better at getting indoors than Three anyway.

Useful link: 4G calling on Sky

There's some free WiFi hotspots from both companies

Sky WiFi banner

How to connect

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If you use London's TFL network a lot, only Three get you free access to the on-station WiFi, out of them and Sky. Every pay monthly plan and pay as you go bundle comes with it. Sky don't offer this.

Sky do have their Sky WiFi network of nationwide hotspots in useful places like pubs, cafes and shops. But this is free to register on anyway and Sky Mobile customers don't get any extra benefit from it.

Getting free WiFi hotspot access with your mobile deal can be a useful way to save on using your data allowance out-and-about or connecting where mobile signal simply can't reach.

But there's loads of free WiFi access out there nowadays anyway - so it's probably not the deal breaker it might once have been.

Useful link: Costs for going over your limit on Three

Our verdict on network features:

Minor win for Three

"Three's WiFi calling and 4G calling being a bit slicker than Sky's just about gets them the better rating here. And it's only Three who offer hotspots you can't already get free."

Compare pricing and deals

Benefits on Three vs Sky Mobile

Free streaming data: Go Binge vs Watch

Is unlimited streaming better on Three or Sky?

Streaming smartphone with Three and Sky logos

Unlimited data for streaming Sky TV apps

Devices with unlimited streaming lettering

Read full guide

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If you're considering Sky Mobile because you've got Sky TV at home, they've got an excellent benefit that will help you get the most out of your mobile package and your TV one:

It's called Watch. It gives you an unlimited data allowance for watching any of Sky's TV apps out-and-about (see the full list), as long as they're included in your home package.

What we really like is that you get it with every single plan (phone, tablet or SIM). So even if you take the cheapest current SIM only plan with the least data, you'll get unlimited streaming included:

There are a couple of limitations, like adverts come out of your data and you have to have some regular data leftover for it to work but otherwise it's a really generous scheme and keeps you entertained.

Useful link: What the Sky Go app can do

Three's Go Binge covers more services

Three Go Binge banner

See latest apps

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If you've not got Sky TV, Three's equivalent scheme Go Binge will be more useful to you. It gives you a separate unlimited data allowance for streaming and using a broader list of services and apps.

You don't get Go Binge on every plan like you do with Sky, you have to take a pay monthly phone or SIM with 12GB or more to qualify for the benefit. Here's the current cheapest SIM only plan with Go Binge included:

But it does cover apps like Neflix and Apple Music, which you don't get on Sky. The restrictions are similar: you'll need some of your regular data left for it to work and ads come out of your regular allowance.

If you're a commuter or travel long distances with kids in the car Go Binge can save you tonnes of data or from needing to buy a much bigger plan than you'd normally have to.

Useful link: Full conditions on the Go Binge scheme

Our verdict on free streaming:

Basically a draw

"This all comes down to what you'll watch. If you've not got Sky TV but do watch Netflix, you've got nothing to gain from joining Sky Mobile and vice versa. Sky's is more generous on low-cost plans. Three's covers a wider range of apps."

Compare pricing and deals

Roaming compared on Three and Sky Mobile

Which network is better for going abroad?

A globe with Sky and Three logos

Three have our favourite inclusive roaming scheme

Three Go Roam banner

See latest countries

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For years now, Three have been our undisputed winner in our best roaming network rankings, thanks to their Go Roam benefit, which you get on all pay monthly deals and pay as you go bundles.

While other networks only let you use your UK minutes, texts and data for no extra cost while you're roaming in the EU (because it's a legal requirement), Three have offered way more worldwide destinations for years.

You can see the full list of included countries here but it includes 71 destinations, with popular long-haul places like USA and Australia covered. These are where you'd rack up huge bills on other networks, including Sky.

It's not a perfect scheme, there are limits on how much you can use while you're roaming and you can't use your phone as a hotspot. But for holidays and other trips, we really rate Three Go Roam.

Useful link: Full roaming guide and all costs on Three

Sky Mobile's roaming is more basic

Sky Mobile roaming banner

What you get

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If you mainly travel within the EU, then Sky Mobile are as good a choice as any other network. You can use your UK minutes, texts and data, without paying extra.

Unlike some of the other mobile networks, you can use anything up to your full monthly data allowance while you're in an inclusive country. There's no fiddly fair usage policy to worry about.

You get 4G while you're roaming and what's really nice is that Sky's unlimited streaming benefit Watch also works while you're roaming within the EU, so you can keep yourself entertained without using up your data.

Overall, you can't go as far with Sky without paying as you go at these pretty-expensive rates but for hops over to the continent, most people will be more than satisfied.

Useful link: Full roaming costs per country on sky

Our verdict on roaming:

Win for Three

"The number of further afield destinations on Three puts them ahead of Sky Mobile in our book. But if you'll never go beyond Europe, it probably doesn't matter which you choose."

Compare pricing and deals

Other extra perks on Sky vs Three

Here's what other benefits you get on each

A giftbox with Sky and Three logos

Keep unused data on Sky and share it

Piggybank showing saved data

Read full guide

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Sky have made it so you can avoid wasting unused data you've bought as part of your plan with their piggybank system - a sort of bank account for spare data you've not used.

At the end of each month, they'll automatically calculate how much you've got left (if any) and put it into your piggybank. Then, if you ever run out of data during a busy month, you can make a withdrawal of 1GB at a time.

If you've got multiple mobile deals on a single account, you can even send data to someone else if they run out. Or you can trade it for discounts off new devices.

It helps you avoid ever paying extra for running out of data. And your saved data lasts 3 years, so you've got ages to use it up or trade it in. Three have nothing similar to this.

Useful link: Sky's full guide to their Piggybank system

Prices and plans compared

SIM only on Sky Mobile vs Three

Do Three or Sky have better SIM only deals?

SIM card with Sky and Three logos



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Added features

Special offers on Three and Sky

Here's what's currently running on the two networks

Special offer ribbon with Sky and Three logos

Phone contracts on Sky Mobile vs Three

Which is better for joining on a phone deal?

Smartphone between Sky and Three logos

Sky's phone contracts are more flexible

Screenshot of credit check

Read what's involved

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When you take a phone from Sky Mobile, you're taking out a credit agreement (basically a loan) to cover the cost of the phone, and then also a monthly plan for your minutes, texts and data - all in one transaction.

This gives the advantage of being able to choose a 36-month deal (for a lower monthly cost, spreading the phone price out over a longer period) or a shorter 24-month one (paid off more quickly).

You can also do stuff like pay off whatever is remaining on your phone payment and upgrade to a new device early or leave Sky altogether without paying cancellation fees, if you're beyond your first 12 months.

We're not so keen on the Swap trade-in part of Sky's phone contracts, because it involves giving up a phone you've paid for. But we do like how you can use the value of unused data for discounts of your next upgrade.

Useful link: Use our phone deal comparison tool

Three's phone contracts are more straightforward

Screenshot of phone comparison tool

Compare phone contracts

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You can join Three on a phone contract directly or via re-sellers like Fonehouse, who can offer better deals (our comparison tool compares all ways of joining each network).

Either way, their deals are conventional 24-month ones, where your phone and usage are all part of the same contract (there's no separate credit agreements or similar).

It means they're less flexible than Sky's. You don't get a choice of contract length and there aren't any early upgrade options. But you can get some good deals on Three compared to some of the other main networks.

Use our comparison tool here to compare all major networks directly and via re-sellers like Carphone Warehouse and more.

Useful link: Three's current phone range

Our verdict on phone contracts:

Minor win for Sky

"If you want a bit more flexibility and to be spread the cost of a phone out over a longer period, Sky are probably more suitable. If you're happy with a regular 24-month deal, either are an option."

Compare pricing and deals

More Sky Mobile articles

More Three guides