O2 Unlimited data SIM

Claire Nottage | November 14th, 2022

O2 logo

O2 is one of the four UK mobile networks and offers several unlimited data plans on one-month, 12-month or 24-month contracts, either as a SIM-only deal or bundled up with a new phone in a pay monthly package.

If you are looking for an unlimited data plan then O2 may be a good place to start, especially as it’s pretty generous when it comes to extras and roaming. We’ve taken a look at the details.

Key features

Here's a quick rundown of what an O2 unlimited data deal has to offer.

Prices from £28 per month
Available speeds 3G, 4G, 5G
Monthly data usage Unlimited
Roaming data usage 25GB
Contract lengths 1 month, 12 months, 24 months
Coverage 99% of UK population
Personal hotspot Yes (unlimited)

Compare O2 SIM deals Visit O2 Mobile

Our review

Since Three first introduced unlimited data deals, they have become increasingly widespread, with most providers now offering some kind of unlimited data option. Prices vary considerably and it tends to be the case that the more premium the provider, the higher the monthly price will be, but the better the perks will be. O2 is one such provider, offering unlimited data plans with a range of goodies attached, including discounted Amazon subscriptions as well as double data for existing Virgin media broadband customers.

O2 offers unlimited data plans either as part of a handset deal in a pay monthly package or in the form of SIM-only. An unlimited data plan allows you to use your phone as a hotspot to get other devices online via tethering without running out of data, and freely stream video and audio even when you are away from home without worrying about hitting a limit.


Map of the UK

As with the other mobile networks, O2 claims that it offers 99 per cent population coverage with its 3G and 4G networks across the UK, which means that unless you live in the middle of nowhere, you should have a good chance of receiving a signal in most places. O2’s 5G network is still in the rollout phase, and currently available in around 200 towns and cities across the UK.

To see what coverage is like in your area, you can use O2’s coverage checker, which shows coverage both indoors and outside for all its networks.

Check O2 coverage


O2 does not offer unlimited data deals with speed limits, unlike some providers, so if you pay for unlimited data, you can be reassured that wherever you are, you will get to enjoy the best speed available.

When it comes to 5G, O2 does not offer the fastest download speeds; that honour rests with Three (with 204.3Mbps). But with an average of 100.6Mbps recorded by market analyst Opensignal, there is little to complain about when you consider this is still faster than the majority of home broadband speeds.

With 4G, O2 offers a rather modest 17.1Mbps, which is on the slow side when compared to EE’s average 4G speed of 44Mbps, but comparable to Vodafone on 21.6Mbps, according to Opensignal.


O2 is one of the best mobile providers when it comes to roaming. There is no extra cost to use your unlimited UK minutes, texts and data in what it calls the Europe Zone. This includes 49 countries, including French overseas territories such as Guadeloupe and Martinique. There is, however, a 25GB monthly limit on data usage in Europe, so if you were hoping to stream a few movies using your unlimited UK data, you’ll be out of luck.

O2 also permits tethering abroad, although it doesn’t recommend it and the same monthly usage limit of 25GB still applies. If you go over the limit, you will be charged £3.50 per every GB you use.

Customers wanting to travel beyond the Europe Zone can sign up to O2 Travel. For £6 per day, this provides you with unlimited data, text and minutes in 27 countries, including the United States, Australia, New Zealand, Canada, Mexico and Argentina. The fee is only applied for each day you use your phone. Although there is no usage limit with O2 Travel, you may find that your connection speed slows, depending on the country you are visiting.

Extras and features

O2 offers a great range of extras with its Priority app, but has a lot of other benefits to offer customers as well.

  • Priority – O2’s rewards app offers reduced and early bird ticket prices on everything from gigs to museums, as well as access to prize draws and also special offers and discounts on subscriptions from Apple Music to Uber One.
  • Extras – Get free access to subscriptions such as Amazon Prime Video, Amazon Music, Audible, Disney+ and magazine app Cafeyn with O2 Pay Monthly .
  • Discounts for Virgin Media customers – If you are already a Virgin Media customer, you can enjoy double data on certain O2 plans when you sign up, as well as a speed boost on your home broadband and up to three Wifi pods for your home, all at no extra cost
  • Free EU roaming – With the majority of other providers now reintroducing roaming, O2 stands out from the crows by continuing to enable free EU roaming for all its customers
  • Upgrade when you want – If you’re keen to get your hands on the latest handsets whenever they come out, O2 Refresh means you can, subject to having paid off your existing device plan first

Compare O2 SIM deals Visit O2 Mobile


Vodafone, EE and Three all offer unlimited data plans, as do a growing number of MVNOs (Mobile Virtual Network Operators),including giffgaff, Smarty, Asda, ID Mobile and Virgin Mobile. Some providers, including Vodafone, offer a selection of different unlimited data plans, priced according to the download speed you will get, so check what the deal is before you sign up.

Cheapest alternatives

If you are after a 5G deal, then Three is one of the cheapest providers out there, advertising some very cheap unlimited plans. iD Mobile, which runs on Three’s network, also offers some equally great value, unlimited plans.

Asda Mobile is another provider offering cheap unlimited data deals, although it throttles its 5G speeds to just 2Mbps. It’s unlimited 4G is not throttled, however and will give you plenty of freedom to stay connected at all times.

Compare unlimited SIM deals

Best alternatives with perks

O2 aside, Vodafone and EE offer some of the best goodies with their unlimited data plans. Vodafone’s VeryMe rewards scheme includes perks such as free Vue cinema tickets, free coffees at Costa and discounts on a range of restaurants. Its so-called Xtras, which come with a handful of plans, are less exciting and include free battery replacement and free picture messaging.

Similar to O2, EE offers customers a range of free entertainment subscriptions including Netflix, Apple Music, BT Sport and Xbox Games Pass as part of its Smart Benefits scheme. The greater the cost of your plan, the more Smart Benefits you will be entitled to claim.

See also