O2 SIM only deals: comparing their best plans in May

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We look at whether O2's current best SIM only plans are decent value compared to all their competitor mobile networks in the UK. SIM Sherpa is your trusty guide. Last updated: 16th May 2022.
O2's best SIM only deals
The best SIM only deal on O2 this month
Out of all the SIM only plans available this May on O2, we'd say their best value deal is their 24‑month SIM below, which gets you 120GB data, plus unlimited minutes and texts for £20 a month:
In comparison to the rest of O2's current SIM only plans, it's one of the best. But it is beatable on price, even if you're set on joining a provider that uses the O2 network. Here are other networks you can beat it on:
Or their £20 for 100GB SIM plan is worth a look too
If you need less data, you might like the £20 SIM only deal running on O2 at the moment. It's a 12‑month plan, which comes with 100GB data, unlimited minutes and texts too:
It does enough to get into our pick of O2's best SIMs but that doesn't mean it's unbeatable on price. Other providers (even ones that use the O2 network) can beat it. See the networks with cheaper plans here:
O2 are also offering 30GB for £15 on SIM only
For a smaller amount of data, we'd say this is one of O2's best deals on SIM only this month too. It's a 24‑month plan, comes with 30GB data, unlimited minutes and texts for £15 a month:
Compared to O2's other deals, this comes out among the best. But it's worth knowing you can get a lower price elsewhere, even on other providers that use the O2 network. Here's which other networks can beat it:
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How O2's deals compare with other networks

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More about O2's SIM only plans
How O2's SIM only prices and benefits compare
In our full review of the O2 network we said we liked their brilliant call signal (3G/2G) coverage, their good 5G coverage and their great WiFi hotspot scheme. We also like their WiFi calling and 4G calling.
You have the choice of 1-month, 12-month and 24-month contracts. Their 24-month contracts are usually much cheaper per month, but it’s best to check their current deals for the best possible offer.
O2 tend to be one of the more expensive UK networks, but their larger data deals are usually a bit more competitive. There are a few cheaper providers who use the O2 network (including Sky Mobile, giffgaff and Tesco Mobile).
There’s a few extra benefits for being on O2. They’re the only main network to offer free inclusive EU roaming. They also offer extras on premium plans like worldwide roaming data passes and free subscriptions to entertainment services.
Useful link: Read our full O2 review
Useful information about O2’s SIM only deals
Your O2 SIM card will arrive between 1-4 working days depending on where in the UK you live. They also have premium delivery options. Your package will contain each size of SIM for any phone, and O2 also offer eSIMs.
When your SIM arrives, you have 14 days to return it and get a full refund if you’re not satisfied. This will also cancel your contract. Here’s how you do that.
To get on a SIM only contract you’ll have to pass a credit check. This is because they don’t want their customers running up a massive bill they can’t pay. If this is an issue then you can pay up front for a payg bundle instead.
And if you’re switching to O2 from another network you can keep your number by requesting a PAC from your old provider and giving it to O2 at any point. Here’s how you do that.
Useful link: Compare all O2 SIMs