There are loads of mobile networks to choose from in the UK, but only four actually have their own spectrum. Those four are of course EE, O2, Three, and Vodafone, while every other network is an MVNO (mobile virtual network operator) that makes a deal with one of those four to access its spectrum and coverage.
On this page we’re looking specifically at MVNOs that use O2’s network – so in other words smaller networks that have the same coverage as O2. And more specifically we’re interested in ones that offer SIM Only plans.
In many cases these networks will be cheaper than O2 itself or have their own selling points, so they’re worth considering if you want O2’s coverage.
Giffgaff has been around since 2009 and it’s owned by O2, so it has the might of a big network behind it.
O2 has positioned Giffgaff as a cheaper alternative, so its plans often cost less than O2’s, and it sells both rolling 30-day plans and longer term 18-month plans, the latter of which tend to have lower monthly prices for the same allowances.
You can also get up to unlimited data on Giffgaff, as well as inclusive roaming in the EU (up to a 5GB fair usage limit). You can also tether, use Wi-Fi Calling and 4G Calling, and 5G comes as standard.
All Giffgaff plans also come with unlimited minutes and texts, and there are no credit checks on Giffgaff’s SIM Only plans. You also have the option of an eSIM.
Sky Mobile is another option for O2’s coverage and this one is less flexible than Giffgaff, as all of its SIM Only plans are 12 months long. That said, it does have the unusual advantage of letting you switch your allowances up or down every month, so you can essentially change your plan at any time, you just can’t cancel for 12 months.
Another benefit of Sky Mobile is data rollover, which allows you to roll unused data over from one month to the next, and it won’t expire for 12 months. Plus, if you’re a Sky TV customer you’ll benefit from being able to use Sky apps like Sky Sports and Sky Go without it eating into your data allowance.
Sky Mobile also offers 5G as standard, all of its plans come with unlimited minutes and texts, and you can get up to unlimited data.
The network also supports Wi-Fi Calling, 4G Calling, and tethering, and it doesn’t carry out credit checks on SIM Only plans (but does carry out identity checks). Note however that roaming costs extra on Sky Mobile.
Tesco Mobile also uses O2’s coverage, so whether you’re using 3G, 4G, or 5G, you should get an identical experience on Tesco Mobile to O2 itself.
The network offers both 12 and 24-month SIM Only plans, and you can get up to unlimited data, with all plans also coming with unlimited minutes and texts.
5G comes as standard, and Tesco Mobile promises no EU roaming fees until at least 2026. The network also supports Wi-Fi Calling, 4G Calling, tethering, eSIMs, and it offers family plans, which provide monthly perks such as money off your bill or extra Clubcard points.
Speaking of Clubcard points, you’ll also get 1 Clubcard point for every £1 spent on your plan, making this a good choice of network for regular Tesco shoppers.
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Asda Mobile 
GiffGaff 
iD 
Lebara Mobile 
Lyca Mobile 
O2 
Sky Mobile 
Smarty 
Spusu Mobile 
Talkmobile 
Tesco Mobile 
Three 
Vodafone 
Voxi 
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