Searching for a mobile network that uses O2 masts?
In this guide, we’ve ranked the best mobile providers that piggyback off the O2 network at the moment.
Later on, we’ve also explained some key things to consider when choosing which of these networks to join.
Best O2-powered mobile networks
Below, we’ve taken a look at the best mobile virtual network operators (MVNOs) that use O2 to provide their service.
1. giffgaff
Often, if you want to use an MVNO, the best one to choose is the provider owned by the parent network.
We’ve found MVNOs owned by the parent network, rather than just leasing access from them, tend to offer unrestricted network performance, meaning you get the full speeds and signal on offer on 4G and 5G.
In O2’s case, this is giffgaff – a small network operator owned entirely by O2.
We’ve found from our testing that giffgaff offers the exact same speeds and signal on 4G and 5G, compared to buying from O2 directly.
Their SIM-only deals offer really good value for money, and come with the choice of a month to month or 18 month contract, depending on whether you want to maximise flexibility, or minimise your monthly cost.
The best thing about giffgaff though is how easy they are to join. On their pay as you go SIM plans, there’s no credit check needed, and it’s also really easy to change your data limit on a month to month basis.
Plus, giffgaff has a good range of reasonably-priced pay monthly phone plans you can choose as well, in case you need a new handset.
2. Tesco Mobile
Tesco Mobile is the O2 MVNO that’s most similar to O2 itself, though they’re not as expensive.
They have a similar range of SIM plans, including options on a contract, and pay as you go options. Plus, Tesco Mobile has a really good range of pay monthly phone deals, offering more handsets to choose from compared to most other MVNOs.
The best thing about Tesco though is their roaming allowances. EU roaming is completely free at the moment, with no fair usage limits, meaning you can use your entire allowance in 48 different countries.
Most other providers have a 10-20GB cap on their monthly roaming usage, no matter how high the allowance you’re paying for is, so this is really good to see from Tesco.
Plus, if you use Tesco Clubcard, you can begin to earn points when you sign up for Tesco Mobile.
Tesco’s customer service is quite good, as is their speeds and coverage. Although, they’re not as cheap as giffgaff if you’re searching for a basic SIM-only deal.
3. Sky Mobile
Sky Mobile is another more premium option, which also uses O2 network masts.
They actually don’t offer month to month SIM only deals. Instead, you have to commit for 12 months or more, and Sky has a much larger range of pay monthly phone contracts on offer.
But as a more premium option, Sky tends to provide better customer service. And they’re a much better choice if you often like to upgrade your phone – they tend to have quite a good range of upgrade deals available on the latest handsets, making it very easy to trade in your phone and get the newest device.
Sky is not the cheapest mobile network, but if you don’t mind entering into an 18, 24, or 36 month contract, they can be worth paying more for.
Similar to giffgaff, we think they offer the full speeds and coverage on offer from the O2 network, even though they’re not owned by O2.
4. O2
If you want to use the O2 network, it can also be worth buying from O2 directly, in certain situations.
The main strength of O2 is their roaming allowances. They have a 25GB monthly roaming limit – it’s not unlimited like what Tesco offers, but this is higher than what the other big four providers give you, and their inclusive roaming allowance covers a good range of different destinations.
Another unique thing about O2 is how flexible their tariffs are.
You can generally customise the structure of the contract, for example, changing it from 24 months to 21 months so you own your phone quicker, or raising the upfront cost to lower your monthly bill. No other mobile networks have this level of flexibility at the moment.
The downside to O2 is, they don’t tend to offer as good value for money as most of their MVNOs, whether you want a SIM-only deal or a pay monthly phone contract.
But in return for the higher prices, O2 contracts normally come with extra benefits that can be rare to find on other networks.
For example, you can get a free speed boost on your Virgin Media broadband plan when you sign up for an O2 pay monthly contract.
What you need to know about buying an O2 network SIM
In this section, we’ve explained some good things to think about when shopping for a new SIM or mobile phone plan on the O2 network.
Which mobile networks use O2?
Currently, the following mobile networks use O2 to deliver their service:
O2 has the lowest number of MVNOs of any of the big four mobile networks at the moment.
Most other small network operators use Three or EE to service their customers, and Vodafone also has a larger number of MVNOs.
Several other companies used to use O2 but have since switched to a different network, or gone out of business. This includes Virgin Mobile, Lyca Mobile, and KCOM Mobile.
What are the pros of the O2 network?
Here are some of the main reasons to switch to a network powered by O2:
- O2 is one of the cheaper big four networks, and its MVNOs, especially giffgaff and Tesco, can offer very good value for money.
- O2 has very strong 4G coverage and speeds in most parts of the UK.
- O2 has the best roaming allowances of any of the big four networks, and often their MVNOs pass these allowances on to their customers.
What are the cons of the O2 network?
However, there are also some downsides to using an O2 network, which it’s worth keeping in mind:
- O2 has the lowest average 5G speeds of any big four network, and their 5G coverage is not the best either. O2 are not currently making the same level of 5G standalone investment as Three, Vodafone, or EE.
- Since there are so few MVNOs on O2, your choices are quite limited when it comes to the number of providers and deals on offer. You may be able to find better value with MVNOs that use other networks.
How other networks compare to O2
If you’re not decided on using an O2-powered provider, you might be wondering how other networks perform in comparison to O2.
Compared to O2:
- Three offers much faster average 5G speeds, though their roaming allowances are much worse, including on smaller networks that use their service.
- Vodafone offers faster 5G and about the same 4G. Buying a SIM-only deal from Vodafone itself can be expensive, and they often have speed caps. However, their MVNO, VOXI, performs better than giffgaff in our opinion, with benefits such as unlimited social media usage.
- EE has stronger 4G and 5G coverage than O2, as well as faster 5G speeds. Buying a plan from EE can be expensive, and like Vodafone, their SIMs are often speed-limited. However, they have a good range of MVNOs to choose from that don’t have speed caps, such as 1pMobile, but none are owned by EE directly.
Use our SIM-only comparison page to see what deals these other networks are offering compared to O2 providers.
Other non-O2 MVNOs worth considering
Apart from the O2 networks we mentioned in the first part of this article, there are a few MVNOs that use other networks you might also want to consider.
- VOXI is a Vodafone-owned MVNO, with fast speeds, low prices, and unlimited social media/video streaming allowances on some of their plans.
- 1pMobile is an EE MVNO with top-tier 4G coverage, fast 5G speeds, and a good range of flexible SIM-only deals.
- Smarty is a Three-owned MVNO with fast 5G, low prices, and a good range of month to month SIM deals that are easy to get started with.
Conclusion
If you want to save as much money as possible on the O2 network, we think giffgaff is normally the best choice.
On the other hand, if you don’t mind paying a bit more for extra benefits such as better roaming, we think Tesco Mobile and potentially O2 itself can be a better option.
If you’re still not sure which MVNO to choose, leave us a comment below, and we’ll get back to you as soon as we can.
About the author
Tom is the founder of Green Smartphones. You’ll find him writing about phones on the Green Smartphones blog, or talking about SIM deals and mobile networks on our YouTube channel. He’s the Android expert on the team – currently using a Google Pixel 9, recently upgrading from a very long-suffering Note 20 Ultra. When he’s not working on Green Smartphones, you’ll find him playing football or hiking.