O2 SIM only deals: comparing their best plans in December

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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: 1st December 2023.
O2's best SIM only deals
The SIM only deal on O2 we rate highest this month
We'd say O2's £17.99 SIM only plan below is their best option this December. It's on a 24‑month deal and gets you 150GB data, unlimited minutes and texts:
You have got other cheaper options if you don't need your SIM to be on a provider that uses the O2 network. But if you do, it is the cheapest current deal available. Here's which other networks can beat it:
O2's 30GB for £12.99 plan is a good option too
If you need less data, we also think this £12.99 O2 SIM is one of their best options. It comes with 30GB data, unlimited minutes and texts on a 24‑month deal:
There are other networks charging less for a SIM with 30GB data or more but this is the best current option with a provider that uses O2. See where you can get it for less here:
Their £25 for 250GB plan is a decent deal for December
To get even more data, O2's £25 SIM below is another of their best deals this month. For £25 a month, it offers 250GB data, unlimited minutes and texts on a 24‑month plan:
It's a good deal by O2's standards but price-wise you can still beat this plan on other providers (even ones that still use the O2 network). Here are the networks offering it cheaper:
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How O2's deals compare with other networks

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More about O2's SIM only plans
O2’s SIM only prices and benefits compared
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’s deals tend to be some of the most expensive of all networks, but they’re a bit more competitive on big data deals. There are some smaller providers on O2’s network who offer better value SIM only deals.
They’re also the only main UK network to still offer inclusive EU roaming on all plans. And you can get extras on premium plans, such as subscriptions to entertainment services and worldwide roaming data passes.
Useful link: Read our full O2 review
Other things to know about O2’s SIM only deals
You’ll get your O2 SIM card between 1-4 working days after ordering (depends on your location). And there are premium delivery options too. You’ll receive each size of SIM for any phone. Or you can take an eSIM.
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 prevent customers racking up huge bills they can’t pay, O2 make you pass a credit check to join them. If you have a poor or no credit history you can still join O2 on a PAYG monthly 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