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The best O2 SIM only deals and plans in May 2021

For many, O2 SIM only deals will represent the perfect choice for their next phone. It stands as one of the four main networks with a wide range of smaller MVNO SIM only deals making use of its technology, coverage and technology.

With its long-standing history, starting off in 1985, O2 has had plenty of time to perfect its SIM only deals. Right now, it fits in neatly next to Vodafone as a very well-rounded platform.

It's not overly expensive, it has a number of big data SIM plans at affordable price points and finds itself discounted throughout the year. On top of that, to compete with increased competition from Three, Vodafone and EE, O2 has increased its presence in the world of incentives.

Including gifts like free Disney Plus subscriptions, boosts to data, half price promotions and more, O2 SIM only deals are looking the strongest that they have in a long time.

So what are the best prices? How do O2 SIM only deals compare to its competition like Three SIM only deals and Vodafone SIM only deals? We've answered all of these questions below.

Compare O2 SIM only deals:

Why choose the O2 network?

O2 SIM only deals

(Image credit: Future)

Is O2 a good mobile network?

In a nutshell, yes. O2 is one of the four main networks, meaning it uses its own coverage and speeds and doesn't have to use another company's network.

Outside of that, it has some of the fastest speeds, some pretty affordable prices and a host of benefits including O2 Priorities, free Disney Plus with certain plans and more.

What kind of coverage does O2 get?

It is. Between 3G, 4G and now 5G,  it reaches 99% of the UK population, and it powers some household names’ networks such as Tesco Mobile and GiffGaff. You can check the coverage map here.

However, that is a very similar level of coverage as the other main options - EE, Three and Vodafone. All four networks have pretty much got coverage of the entire country at this point.

What benefits do O2 SIM only deals offer?

O2 offers a number of benefits with its SIM only deals. Firstly, the large majority of its plans offer unlimited calls and texts, although that is now common place.

Secondly, you get free access to O2 Wi-Fi hotspots when you're out and then with selected plans, O2 will throw in free subscriptions to Disney Plus, Deliveroo or other apps.

Finally, one of O2's biggest benefits is its Priority reward scheme. This rewards you with free coffees, gig access and more. The only other network that has a similar benefit is Vodafone with its VeryMe scheme.

Is Three a 5G network and do you have to pay more for it?

Yes, like the other main networks, O2 now offers 5G. In fact, every single one of O2's SIMs comes automatically with 5G so you don't have to pay more to get it.

If you do want to access 5G you do have to have a 5G phone first. This is most of the recently launched phones of a higher price. Think iPhone 12, Google Pixel 5, Samsung Galaxy S21 and more.

How to switch to a O2 SIM:

O2 balloon

(Image credit: SM)

How do you switch SIM providers?

Firstly, you need to know you're eligible to switch plans. If your contract still has a few months until it ends, you are likely to be charged for the remaining time meaning it is usually best to fully finish your contract first.

Switching and keeping your number:

Once you know when your contract is finishing and you've got your new deal, you need to decide if you want to keep your number. If so, you can request a PAC code (Porting Authorisation Code) from your old network. This can be done via the phone or through a text.

Then you simply get in touch with O2 and give it your new code.

Switching with a new number:

Don't want to keep your number - it's even easier! Simply get in contact with your new provider and tell them you want a new number and tell your old network your ending your contract.

This can also be done via a text to switch service. Simply text STAC to 75075.

What SIM card size do I need?

SIM cards these days fall into three sizes and these are: Standard, Micro and Nano, descending in size. More on eSIMs below. If you're ordering your SIM only you'll likely find it arrives in a credit card sized piece of plastic out of which can you pop your microchip SIM.

A standard SIM measures 25 x 15mm and was used in phones before 2010 and a few after then.

The Micro SIM stands at 15 x 12 mm and was used in phones from 2010 and you'll still find some phones work with these now.

The Nano SIM, introduced in 2012, measures in at 12.3x 8.8mm and is the most commonly used SIM in phones.

The Combi SIM might be what you get sent by a SIM only provider as it contains all three sizes, and you push out the one that fits your phone. This is ideal as you don't need to know your size prior to this as you can hold it up to the SIM tray and see.

What factors should I consider?

O2 SIM only deals

(Image credit: Future)

What contract length should I get?

O2 offers three different kind of contracts - 18 months, 12 months or a 30 day SIM. However, the shorter your contract, the more money you will end up paying.

O2 is by no means the cheapest option around for 1-month rolling SIM plans with the likes of Smarty, iD Mobile or Voxi offering much cheaper prices.

O2's best prices come on 18 month contracts if you don't mind committing for a little bit longer. If you use the comparison chart at the top of the page, you can filter by contract length.

How much data, texts and calls do I need?

The large majority of O2 SIM plans come with unlimited calls and texts, and those that don't will offer at least a couple of thousand of each. However, data caps do range drastically.

To decide how much data you need, you can simply think about how much you used on your old contract and try and match that. If this is your first phone, then here's a rough guide:

  • 1GB: A limited option that won't be enough for most. If you rarely use the internet and occasionally need to use Google Maps or check the internet, this can be a cheap option.
  • 5GB-10GB: This is the range most people will fit into. It allows for pretty intensive usage of social media, Maps and internet searches without fear of running over. While you can do a bit of streaming, don't push it and avoid HD!
  • 10GB-50GB: If you like to stream when you're out and about, use maps on a daily basis and generally have a data intensive lifestyle, this will likely be a cap you should be looking in. Keeping under 50GB can keep your costs at a still affordable point.
  • 50-100GB: At this point, you're going to have to be a real data drainer for this to be necessary. Downloading apps on the go, HD streaming, big downloads and working from home.
  • 100GB-unlimited: Unlimited data plans have significantly come down in price over the years and can even be a legitimate alternative solution to having full broadband if you live somewhere with an excellent 4G/5G connection. However, for most people, it's not going to be necessary.

What sort of price should I expect to pay?

This depends on a wide range of factors: how much data do you need? How long do you want to be tied in? Do you want added extras with your plan?

If you're looking for a low data plan, you should be able to duck your bills below £10 a month. However, if you're looking for a lot of data, maybe even unlimited, you'll be looking at a price in excess of £20 a month.