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Sky Mobile vs O2:
key differences between the 4G/5G networks

O2 and Sky Mobile logos and Vs letters

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Both Sky Mobile and O2 use the same network, so we check if there are any coverage or speed differences and compare their other benefits head-to-head. SIM Sherpa is your trusty guide. Last updated: 21st April 2021.

In our O2 vs Sky Mobile guide

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Sky Mobile vs O2 networks

Are there coverage differences between Sky Mobile and O2?

We testd both networks to find out

Signal bars with Sky and O2 logos

4G, 3G and 2G is identical on Sky Mobile and O2

Sky Mobile and Telefonica deal screenshot

See the claim

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Sky Mobile are fairly obviously owned by Sky. While O2 are owned by a company called Telefonica. Sky Mobile have always used O2's network and have just signed a long-term deal to use them in future too.

Sky Mobile customers get full access to identical 4G, 3G and 2G coverage to being on O2 directly. So if you've been with O2 before, you shouldn't notice a diffference swapping to Sky Mobile.

If you've been with neither before, they're a good choice for having the joint-largest amount of the UK's physical geography covered with calls and texts. And they've got 4G in 98% of the places people live.

But we still recommend using either networks' coverage checkers below to test signal away from where you live. Think about your route to work/school or places you regularly travel to away from large towns.

Useful link: Which network has the best indoor signal?

5G is live on Sky and O2 in the same places

Sky Mobile 5G banner

How to get it

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If your current or next phone's got 5G as a feature, both Sky and O2 are options to join to get the faster technology with your plan. And they use the exact same infrastructure.

Even though Sky report fewer locations on their website, we think it's just they aren't updating these as often. We're pretty sure you get 5G in the same 150+ towns and cities as O2.

You get 5G at no extra cost on both, though you have to choose it as an add-on on Sky or tell O2 in the checkout that your phone is 5G-ready when you order with them.

We've tested 5G on both Sky and O2. We'd say their 5G coverage checkers are accurate about where they do and don't have it. Although on the edge of coverage areas, the quality is no better or worse than their 4G! We also had trouble with getting 5G on Sky to work on a non-mainstream Android brand phone.

Useful link: O2 latest 5G rollout news

Use Sky or O2's coverage maps to check your local signal

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

Sky coverage checker

Sky's coverage map

Check Sky signal

using their official map
(opens in new window)

O2 coverage checker

O2's coverage map

Check O2 signal

using their official map
(opens in new window)

Our verdict on coverage:

No current winner

"As they both use the same masts across the UK, coverage isn't something that makes a difference between choosing O2 or Sky Mobile. Price and benefits are more important."

Compare pricing and deals

Data speeds: are they the same?

Is Sky Mobile slower than being on O2 directy?

Speedometer with Sky and O2 logos

Get the same 4G/5G speeds on Sky Mobile as O2

O2 5G launch banner

5G rollout latest

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Independent mobile network testers Opensignal and Speedtest by Ookla put O2 as having the slowest typical 4G download speeds among the UK's four mobile networks at 18.0 Mbps and 16.95 Mbps.

Although you probably wouldn't notice the difference between this and faster networks on everyday internet browsing, things like large downloads and ultra high definition streaming might be less seamless.

Limited testing in London Speedtest suggests you can expect typical 5G downloads around 181.19 Mbps on O2, peaking at 289.65 Mbps. We've found 5G speeds degrade quickly away from directly near the transmitters though.

Our testing of a Sky and O2 SIM side-by-side found no evidence of a speed cap on Sky Mobile vs being on O2 directly, so we're confident there's no speed differences between joining either network - so this needn't be something to use to decide between them.

Useful link: More about O2's 4G

Our verdict on speeds:

Honours even

"None of our testing has ever been able to find any evidence of a speed difference between Sky Mobile and O2, so it shouldn't be a reason to choose one over the other."

Compare pricing and deals

Other network technology on O2 and Sky Mobile

How else do they keep you connected?

Gears icon with O2 and Sky logos

O2 have WiFi calling, 4G calling and free hotspots

O2 WiFi and 4G calling banner

See supported phones

(opens in new window)

O2 (and therefore Sky) use some of the best frequency mobile signal for getting into buildings to make calls. But even so they still have a couple of backups too: WiFi calling and 4G calling.

WiFi calling lets your phone make/take calls over WiFi wherever there's no mobile signal. And 4G calling lets your phone use 4G for calls, instead of just 2G/3G, meaning better coverage and higher quality audio.

That's great if it all works but we don't rate O2's WiFi calling as highly as others, as it doesn't support SMS text messaging, you only get it on pay monthly and there are issues around whether O2 will support your phone.

One nice extra network feature on O2 is that you'll get free automatic access to O2 WiFi hotspots around the country. These save your mobile data allowance and might get you a faster connection than 3G/4G.

Useful link: O2's guide to all their network features

Sky Mobile have WiFi calling and some free hotspots

Sky Mobile WiFi calling

See supported phones

(opens in new window)

Like O2, Sky Mobile also offer WiFi calling with their pay monthly plans. And like O2, there's quite a few compatibility issues with Android phones (iPhones should be ok).

If didn't buy your Android phone from Sky, with their software pre-installed, they don't guarantee it will work (our tests confirmed that WiFi calling did not work on an Android phone bought elsewhere).

4G Calling (VoLTE) also now works on Sky Mobile too, which used to be a difference between them and O2 but is no longer an issue.

Like O2, you'll get free access to Sky WiFi hotspots around the country (these are free to anyone already though). But you won't get free WiFi on London's TFL network like you do on O2.

Useful link: Full help guide on Sky's WiFi calling

Our verdict on network features:

Minor win for O2

"You've probably got more chance of O2's WiFi calling and 4G calling supporting your phone, and they've got WiFi on the Underground and automatic hotspot recognition as an advantage over Sky."

Compare pricing and deals

O2 vs Sky Mobile benefits

Unlimited streaming data: O2 vs Sky Mobile

We look at what both providers offer

Play video symbol on phone with Sky and O2 logos

Sky Mobile customers get free data to stream Sky TV apps

Unlimited streaming with a tablet and phone

See all features

(opens in new window)

For us, the very best benefit about joining Sky Mobile is that you'll get unlimited streaming data to watch Sky's TV apps with every single plan for free. Watch as much as you like, it won't come out of your mobile data.

Streaming just a one-hour long episode of a programme could use around 1GB data, so it's a really valuable benefit for anyone who's got a Sky TV package and want to watch it while you're out of the house.

It comes even on the very cheapest SIM only plans with only 1GB/2GB themselves (typically around £6 a month). So it's an incredibly generous offer from Sky. Here's the current cheapest plan with it:

We've tried it ourselves and it's really liberating. You can fill time on long journeys without having to hold back. And it gets more out of your home TV package if you can watch out of the house too more.

Useful link: Sky's full guide to free streaming data

O2 have unlimited data plans as an option

O2 Limitless data banner

Read full terms

(opens in new window)

There's nothing similar to Sky's streaming benefit on O2 (see our guide to all other networks with free data for streaming or social media schemes here). But it is possible to buy unlimited data for any use.

You can get it on select O2 top-end model phone contracts. Or on SIM only there's a couple of unlimited data plans:

Sky don't currently do anything similar, although all these networks do offer unlimited data too.

Useful link: O2's guide to their unlimited data tariffs

Our verdict on streaming data:

Easy win for Sky Mobile

"Getting unlimited streaming data on even the very cheapest SIM only plans on Sky is something O2 don't get close to, where you have to buy a top-range plan for unlimited data"

Compare pricing and deals

Roaming compared on O2 and Sky Mobile

Which gives you more inclusive roaming?

O2 and Sky logos with a globe

O2 offer some worldwide inclusive roaming

O2 free EU roaming banner

Read roaming guide

(opens in new window)

As a minimum on O2, every pay monthly phone or SIM only contract includes inclusive EU roaming, where you can use your plan's minutes, texts and data in these countries for no extra cost.

But there are also options to get inclusive roaming in worldwide destinations outside of Europe. Either choose a plan with that includes the O2 Travel Inclusive Zone or buy a daily pass while you're abroad (see latest costs here).

Then when you're in one of the 27 extra worldwide countries included in O2 Travel, you'll get a daily allowance of 120 minutes and 120 texts back to the UK and a lean 150MB of data at full speed - after which O2 slow you right down to constrain your usage.

We think that should cover most people's basics while they're away on a temporary trip, although it doesn't go as far as the winners of our best mobile network for roaming rankings.

Useful link: All other roaming costs on O2

Sky only really offer inclusive EU roaming

Sky Mobile roaming passport banner

See costs & countries

(opens in new window)

If you're going abroad to any EU country, you'll be able to use your plan's regular minutes, texts and data at no extra cost - you can use your entire data allowance there. That's all pretty standard.

Sky Mobile don't really have any other form of inclusive worldwide roaming included as part of their plans. If you want to go elsewhere, you're looking at paying extra.

That will either be via Sky's Roaming Passport Plus, which lets you use your plan's minutes, texts and data for a fixed daily cost in certain countries including the USA (see latest costs and destinations here). Or you can pay as you go anywhere else in the world.

Either option can quite quickly add up to large extra bills, so if you're a regular traveller outside the EU, take a look at the networks in our best free roaming guide here to save on costs.

Useful link: Sky's full guide to roaming on their network

Our verdict on roaming:

A win for O2

"If you only ever go to EU countries, there's nothing to split O2 and Sky. But if you go further afield, O2 have more options to keep costs down, although your basic plan might end up costing more itself."

Compare pricing and deals

Data rollover on Sky Mobile vs O2

Both networks have unused data schemes. Here are the differences.

Repeat symbol arrows with Sky and O2 logos

Sky Mobile let you keep data longer than anyone else

Sky Piggybank banner

How it works

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Whether you take a phone contract or a SIM only plan from Sky Mobile, you'll get their Roll benefit included as standard. This lets you keep data you don't get through for up to 3 years - to use later or share with others.

Each month, they'll total up what you've not used and move it to your Piggybank (like a savings account for data). Then if you ever run out one month, you just take data out again 1GB at a time.

There are also two added benefits. If you've got multiple Sky Mobile deals on your same account for friends and family, you can transfer data over to them. You can also exchange it for discounts off phones and tablets.

Out of all the data rollover schemes in the UK, we rate Sky's as the best one, simply because you keep data the longest and that you can put it to use in other ways. No other network is as flexible.

Useful link: Sky's help article about data rollover

O2 only really offer data rollover on Pay As You Go

O2 data rollover

See qualifying plans

(opens in new window)

You can't get a pay monthly plan with data rollover on O2. But if you ever have to buy more data because you run out, they will let you keep anything from that extra block for later.

The only plans O2 sell with data rollover as standard are their Pay As You Go Big Bundles. These are bundles of minutes, texts and data you buy out of credit you've topped up with.

Generally speaking, these bundles are worse value per minute, text and data than O2's pay monthly plans. But they do have more flexibility, as you've got no contract and you change, stop or pause bundles as you please.

Useful link: See latest O2 Big Bundle prices

Our verdict on data rollover:

Win for Sky Mobile

"Sky's data rollover lasts longer than O2's and comes on pay monthly plans, which more people will be interested in than pay as you go."

Compare pricing and deals

Prices and plans compared

O2 and Sky Mobile special offers

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

Special offer tag with O2 and Sky logos

SIM only deals on O2 vs Sky Mobile

Which network has the best value plans?

Mobile SIM card with O2 and Sky logos



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Added features

Phone contracts on Sky Mobile vs O2

Do O2 or Sky Mobile have better smartphone deals?

Smartphone with Sky and O2 logos

O2's phone contracts are among the most flexible

O2 custom plans

Read why

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When you take out a phone contract on O2 directly, most models are offered on their Refresh tariffs, which split your deal into a credit agreement (loan) for the cost of the phone, and a monthly usage tariff for your minutes, texts and data.

This gives you the benefit of being able to upgrade early by paying off whatever's left of the cost of your phone (the balance of your loan), without having to pay any other fees for the minutes, texts and data.

O2 have now added more flexibility too through their Custom Plans. These let you choose a contract length anywhere between 3 and 36 months and how much you're willing to pay up front - all without changing the total you pay for the phone.

The benefit of that is you can play with the amounts to get a monthly and upfront payment you're happy with. The downside is, there's now thousands of combinations to choose from.

Useful link: Read O2's guide to their Custom Plans

Sky's phone contracts are based on finance too

Sky Mobile Swap

How Swap works

(opens in new window)

Sky also split your phone contract into two parts: a finance agreement for the phone, and a usage plan for your minutes, texts and data. You can choose two contract lengths: 24 months and 36 months.

24-month contracts spread the cost of the phone over a shorter time, so cost more per month but less overall. 36-month ones cost less per month but more overall.

Sky are keen to push their Swap benefit on phones. It's a scheme that lets you "upgrade for free" after 12 months on Swap12 (24-month contract) or 24 months on Swap24 (36-month contract).

We'd recommend not bothering with the early upgrade element of the contracts, because it involves giving Sky back the phone you've been paying off for up to 24 months - it's like selling your phone below its value.

Useful link: Full ins and outs of Sky's Swap

Our verdict on phone contracts:

Win for Sky Mobile

"We think more people will prefer Sky Mobile's lower prices than the flexibility to choose a shorter contract or large upfront cost on O2. The key is to compare to find the best deal."

Compare pricing and deals

Other Sky Mobile guides

More articles about O2

Other mobile network reviews

Networks ranked by benefits