O2 review 2025: best coverage, slowest data speeds
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We joined O2 on a SIM only plan, to see if you should too. This is our experience of their 5G/4G coverage, speeds and other network benefits. Last updated: 26th November 2024.
Overall rating
SIM Sherpa rates O2 as a very good network to be on
(3.5/5, very good)
"For having signal to make calls and sends texts, no one beats O2. But their data coverage is beatable and their 4G speeds are a bit of a let down for advanced users. Their 5G is temperamental too.
They’ve got all the extra network features a main network must have, like 4G calling, WiFi calling and one of our favourite free hotspot schemes. O2 are a very safe pair of hands network-wise.
O2 have done well to keep EU roaming inclusive on every plan and even offer some worldwide locations on selected ones. Their customer service has an excellent record too.
If you’re someone who wouldn’t describe themselves as an expert and just wants a service that works reliably, without being the fastest and flashiest, we think you’ll be very happy on O2."The 3 best bits
1) Last major network to keep EU roaming
2) Excellent mix of coverage
3) Decent phone contracts
The 3 worst bits
1) Slowest 4G speeds on average
2) Tough phone contract credit requirements
3) No recent innovative extra benefits
Is O2 owned by BT?
No. O2 was long owned by the Spanish operator Telefonica but they have recently just been bought by Virgin Media.
Can I move my number to O2?
Yes. Text PAC to your old provider on your old SIM to the number 65075 and give O2 the code. They’ll transfer your number over within a working day.
Why is O2’s 4G so slow?
We think a lot of the reason O2 are slower for 4G than others is how they’ve implemented the technology. They don’t have as many frequency bands working together. And they’ve likely achieved bigger 4G coverage with longer range transmitters, at the expense of speed.
Is O2's network any good?
Coverage on O2 is now the best of any network overall
As other networks begin to shut off their 2G/3G, we’ve started noticing coverage on them getting worse. O2 are not doing this as fast and it’s paying off. We now think they have the best mix of signal.
We’ve found their call coverage (2G/3G) to be the best of any network, indoors and out. They cover more of the UK’s physical landmass than the others and use good frequencies for getting signal into buildings.
O2 are beatable for 4G data coverage. In our tests in rural areas, we found we were more often bumped down to 3G on O2 than on Vodafone, EE and Three. In urban areas, there are little to no gaps for 4G though.
Finally, O2 provide 5G in a huge list of 3000+ UK locations and tend to cover these very well. It all builds into a picture of leading UK coverage. But do use their network map here to check how signal is in the places you’ll use your phone.
Useful link: Other networks that use O2
4G/5G data speeds on O2 can be a bit of a let down
While coverage is a big strength on O2, their data speeds are a bit of a disappointment in comparison. We use data from independent network testers and our own tests to back this up.
Through our testing we got speeds as high as 95 Mbps and as low as 5 Mbps on O2, but more often we averaged around 15-20 Mbps. This lines up with Opensignal’s typical speed result of 23.1 Mbps for O2.
We wanted to see what speeds on O2 will look like in real life and how they compare to the results from Opensignal. We found that their results line up well with our tests.
Our speeds dropped to about 6 - 7 Mbps in smaller towns and as low as 5 Mbps in the countryside. Speeds did manage to reach as high as 95 Mbps in the city centre, but we most often sat between 15 - 20 Mbps.
You won’t notice a massive difference in speeds when browsing the internet compared to other networks, but tethering to large screen devices will be noticeably slower when loading pages or videos.
O2 tend to offer similar speeds to what you’d expect from non-fibre home broadband. You should generally be able to stream HD videos smoothly, but things like file sharing or gaming will be noticeable slower.
As for 5G, Opensignal and Speedtest put typical speeds between 80.1 Mbps - 85.08 Mbps on O2. That’s much slower than the other networks, but their peak 5G speeds of 229.54 Mbps are still very fast.
The reports and our own findings reveal that O2 can offer some very fast speeds, but most of the time they’ll lag behind the other networks. This should give you pause for thought if speeds are an issue for you.
Useful link: You can test and return your SIM if you're not happy
WiFi/4G calling is a decent enough feature for most on O2
Every network can struggle to get call signal into buildings. This is where WiFi/4G calling come in handy by letting you connect to calls with WiFi/4G signal if conventional call signal is too weak.
O2 have one of the best schemes around. You can transfer from a WiFi to a 4G call without it dropping if you lose WiFi signal, and you can send/receive SMS texts over WiFi/4G. Not all networks offer this.
We tested both features using a manufacturer-bought Android phone and an iPhone we bought from a different network. We got WiFi calling and 4G calling to work on both, but we had to turn it on in our account first.
Other providers will display a special symbol to let you know you’re making a call over 4G, but O2 don’t seem to have this. But don’t worry, this doesn’t mean it isn’t working.
WiFi calling will only “kick in” when you’re somewhere with very weak call signal, but it should work on its own. In our testing we struggled to get somewhere with weak enough call signal to get it working, however.
We were connected to calls over WiFi at the same speed as on regular call signal and the quality was clear. We also managed to switch from a WiFi to a 4G call without it dropping (it will drop if you then lose 4G).
If your phone is from O2 directly it should be compatible for WiFi calling. But you may run into more issues getting devices bought elsewhere to work with O2’s WiFi calling than on other networks (check yours here).
O2 support most iPhone models for WiFi calling, but they’re defensive about whether Androids bought from them are supported or not. But our manufacturer-bought Android phone worked fine when we tested it.
Useful link: How to set up WiFi calling on O2
WiFi hotspots are O2’s best extra network feature
O2 have the best WiFi hotspot scheme, with 15,000+ of them around the country and London Underground to keep you connected and save data. No other network comes close to providing their customers anything like it.
You can use your phone as a personal hotspot to tether other devices to your data signal with no limits on every O2 plan. You can do this even while you’re abroad too.
O2 include call forwarding too, letting you leave one number free from incoming calls by diverting them automatically to another. They don’t include it on PAYG, but to be fair Three are the only network that do.
You can also customise your voicemail as you like and on top of this O2 include visual voicemail. Not many networks do and this lets you sort through your voicemails one at a time, if your phone supports it.
O2 make it easy to join on an eSIM. You can download the information for your eSIM right to your phone using their guide here, rather than waiting for a SIM package to arrive which you will have to on some networks.
Useful link: How to get an eSIM on O2
O2's perks and extras reviewed
Inclusive EU roaming on every plan is a massive upside
While the other main UK networks (EE, Three and Vodafone) have either removed inclusive EU roaming or restrict it to their premium deals, O2 still let you roam in the EU on all of their plans at no added cost.
You can use your O2 plan in any of these 48 EU/EEA destinations. You’ll be able to use up to 25GB of data while there, unless your plan is smaller than that in which case you can use up your entire allowance.
Or if you want to go beyond the EU, O2’s Travel Inclusive Zone is an excellent benefit. This lets you roam in these 27 non-EU countries with an allowance of 120 mins, 120 texts and unlimited data, but at severely capped speeds.
These offers let you roam in 75 destinations at no extra cost:
They’re a great choice for going beyond the EU, even if they’re a bit behind Vodafone and Three. Their EU roaming is where they really shine. Put together, this is why we’d say O2 are the best network for roaming.
Useful links: The best networks for going to the EU and beyond
O2’s Priority is the best of their other extra benefits
O2’s well known Priority rewards app is the best customer loyalty scheme of all UK networks. And we really like that you get access to it automatically on any of their plans, whether on pay monthly or Pay As You Go.
These include discounts on high-street food, drink and entertainment that many will like. Even better, you can get presale tickets for O2-sponsored events which adds some welcome value to your deal (see more here).
If you want to get your kids on their own plans, O2 give you a nice 20% discount on extra deals on your account. You can get a good amount off O2’s SIM only or usage (mins, texts, data) plans of any phone deal.
Finally, O2 offer a free trial to Disney+, Amazon Prime Video and more, which can last 3-6 months depending on your plan. It’s a small extra that can get you extra value on your plan, but nothing earth shattering.
Useful link: O2 Priority help guide and FAQs
They also offer a handful of smaller benefits too
On top of the headliner benefits we went over above, there are a couple of smaller but still very useful benefits that can make your time on O2 a bit smoother:
They allow you to cap any spending on extras outside your plan. They’re fairly flexible on this, but they don’t let you set it in £1 increments like some do. Every provider has to let you set a limit anyway.
O2 automatically block adult content over data signal, meaning you can be sure your kids are safe online. You will have to set separate content restrictions for your home WiFi, however.
In all you get a good package of benefits for joining on O2. But there are benefits like free data streaming that Sky Mobile and VOXI offer that O2 don’t. And you don’t get data rollover. But O2 still offer a lot.
Useful link: Our guide to the most flexible spending caps
Comparing O2's deals
Different sorts of deals O2 offer
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✔ O2’s Custom Plans are more flexible than other networks
O2 offer more flexible phone contracts than most mobile networks, letting you set it between 3 and 36 months. Over this time you’ll pay back the cost of your phone on a finance agreement, which works like a loan.
You can set a length that suits your budget and needs, whether you’d rather pay more or less per month or for a longer or shorter time. Most networks have preset contract lengths that are way less flexible.
And while some networks make you pay more for your phone on a longer contract, O2 keep the cost of your device the same no matter what. But you will technically pay more as you’ll stay on your usage contract longer.
These finance contracts give you the flexibility to pay to reduce your bill or pay off the whole cost to upgrade early. Their phone costs are comparatively low, but their usage plans tend to be expensive.
In all, we’d say they’re a super safe, flexible option that may just be worth spending a little bit more on to join.
Useful link: How building your own plan works
O2 customer service reviews
O2’s customer service has a very bad record with Ofcom
Customers will inevitably run into issues with their mobile network and have to get in contact to get them resolved. If a provider doesn’t solve their customers’ problem, the customer has other options available.
If a network is unable to resolve a customers’ issue online then that customer can make a complaint to government regulators Ofcom. Their record shows how many complaints they got about each network.
A while back, we had problems connecting to 4G signal on our O2 SIM, as it was seemingly stuck on 3G. So we used this as a chance to try out O2’s customer service to see how good they were at helping out.
Their call agents were UK based and politely and professionally helped us in getting our issue resolved.
It took them a few days to resolve our issue, but they were incredibly apologetic and offered to give us financial compensation for the days spent with no 4G.
This test was done a little while ago and seeing how much their reputation has decayed since then we’ll have to test them out again. If we run into any major issues getting help we’ll update this section here.
O2’s customer service record has got significantly worse, doubling from Ofcom’s last report of 3 to now 8 complaints per 100,000 customers. That’s twice the industry average number of complaints of 4 per 100,000.
This rise in complaints could be a result of O2’s 2G/3G switch off beginning to affect customers. Or there may be some behind the scenes changes to how they staff their customer service.
Useful link: How to get help on O2