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Switching to a provider that doesn't raise prices mid-contract could save you money. Compare our best SIM Only deals today
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Uswitch services are provided at no cost to you, but we may receive a commission from the companies we refer you to. To find out more about how our site works, click here. If a deal is ‘promoted’ on Uswitch’s tables, then it has been lent additional visibility as a result of us securing exclusivity on a great deal, or a commercial agreement to showcase what we believe to be market-leading value to consumers.
*£321 is our calculated savings figure from September 2022, which details the potential amount a customer could save per year by keeping their handset and switching to a SIM only deal on Uswitch. See more here: Uswitch savings

Author Ray Ali Last updated March 14th 2023

What is a SIM only deal?

A SIM only phone deal gets you data, calls and texts for a monthly charge. The difference from standard pay-monthly phone deals is that you don't have to pay for the mobile phone. All you're paying for is the SIM card and the allowances.

"According to the latest mobile phone statistics provided by Ofcom, contract bundles (including SIM only deals) contributed 82% towards UK mobile revenue at the start of 2022. So it’s fair to say they are a popular option when it comes to choosing a mobile phone plan.

The best SIM only deals offer varied options for all types of mobile phone user. From low cost deals to unlimited data, the flexibility is a big attraction to people who don't want to be tied down to a pay monthly contract. Compare our best SIM only deals today to find the perfect plan for your personal mobile phone needs."

How does a SIM only deal work?

SIM only deals are very straightforward: you just pick a deal based on how much mobile data you want each month, as well as extras such as minutes and calls. Then you get sent a SIM card to insert into your phone, and you're all set.

Why choose a SIM only deal?

SIM only deals are perfect if you already have a phone you're happy to carry on using, or if you'd rather just pay for a handset outright without a long-term contract attached.

If you stay on the same price plan once your contract ends, your network could carry on charging you the same amount as when you signed up. This means you may still be charged for a handset that you've already fully paid off - and spending way more than you need to as a result.

If you do have a new smartphone in mind that you'd like to purchase, buying it outright could save you money, too. While it'll cost more initially, SIM only deals are usually much less expensive per month than a handset + SIM plan, so you could make the money back over the length of your contract.

Essentially, SIM only deals often give you great plans with plenty of data, minutes and texts for a fraction of the price of a contract plan.

Our featured SIM only deal

SIM detailsLebara Mobile SIM card
Monthly price£6.95 p/m
Data allowance15GB
Contract lengthNo contract
ExtrasEU roaming included

What are our best deals at the moment?

SIM only deals come in thick and fast. It’s a competitive market with networks big and small all trying to out-do each other with enticing deals. That makes SIM only a great option for customers. And if you’re looking for our best deals, you should keep a few things in mind first.

How long do you want your contract to last? Our best SIM only deals come in a range of lengths - including 30-day, 12-month, 18-month and 24-month plans.

How much data do you need? SIM only deals will include a specific amount of data you can use every month. From 6GB to 10GB and all the way up to unlimited data, you can choose from a wide variety of data allowances across networks to suit your usage.

What network do you want to join? We offer deals from all major UK mobile networks. You can compare SIM only contracts from Vodafone, O2, Smarty, VOXI, Three, giffgaff and more.

How to choose the best SIM only deal

Several factors will come into play when choosing the right SIM only deal for your needs.

What are the benefits of a SIM only deal?

They're great value for money, they're flexible, they can include lots of data and much more.

There aren't many cons, with the only main downside being that they don't come with a mobile phone included in the deal, so you will need a handset of your own to use the SIM card.

How much data should I look for in a SIM only deal?

How much data you need is all down to how much data you actually use on your phone. According to Ofcom, the average mobile phone user in 2021 used about 5GB per month while connected to mobile data on their smartphone.

That amount of data covers things like browsing the web, checking email, scrolling through social media and watching the odd video.

But if you love streaming video and regularly listen to music and podcasts while you're out and about and not connected to Wi-Fi, you'll probably need quite a bit more.

If you want to see how much data you're using, all you have to do is take a look at your network's app on your phone.

You should find a detailed breakdown of exactly how much data you use on a monthly basis.

With this info you should be able to make a well-informed decision on the kind of mobile plan you need, unless of course you plan to change your usage. Either way you'll have a clear view of how much you're using.

What length of contract should I choose?

You can choose from 30-day12-month, 18-month and 24-month plans. You'll likely pay less for a longer deal, but get more flexibility with the 30-day offer options.

The length of contract you choose comes down to your personal preference. If you’ve got a smartphone you’re happy to use for the long term and want a big data deal then you could be well suited to an 18 or 24-month plan.

But if you’re unsure of how long you’ll use your current contract, then it might be best to get a rolling 30-day deal.

However, different networks offer different types of SIM only deal, and you might not be able to get every contract length on every network. For instance, you’re more likely to get a cheap 30-day deal on a network like giffgaff or SMARTY, while larger networks like Vodafone and O2 offer the most longer-term contracts.

It’s best to shop around to find your perfect price plan.

What SIM card do I need?

When you get a new SIM only deal, you need to make sure you get the right SIM card for your phone. You can find out which SIM card you need in your phone's instructions, or if you no longer have those, a quick Google of your smartphone's make and model will reveal which card you need.

These days most networks send out a three in one SIM card, so no matter what phone you have, you can adapt the provided SIM card to fit.

Want a pay monthly contract instead?

Take a look at some of our best deals today and compare pay monthly offers from all the major networks.

Woman smiling browsing SIM only deals

Which mobile phone network is best for SIM only?

With many networks competing on the market, you'll a range options for every type of smartphone user.

From pay monthly packages to SIM only deals, with lot of data for downloads and socials or maybe just enough minutes and texts to stay in touch with friends and family - figuring out what you need from a mobile plan is the first step to picking the right network.

Each year we highlight mobile networks in our Uswitch Awards, recognising the best in the market customer service, coverage, roaming and more.

Determined by consumer research as well as the decisions of a panel of judges, comprised of technology journalists and industry experts, these awards represent a seal of quality.

Take a look at the 2023 winners to see how the networks did in a selection of different categories.

Uswitch Awards 2023 winners

Best SIM only networksWinnerHighly commended
Network of the YeargiffgaffTesco Mobile
Fastest Mobile Network - Powered by OpenSignalEEVodafone
Best SIM only NetworkBTTesco Mobile
Best Network for Customer ServiceTesco MobileEE
Best Network for DataEEVodafone
Best Network for RoamingO2giffgaff
Most Popular Mobile NetworkO2Three
Best Pay Monthly NetworkTesco MobileEE
Best PAYG NetworkgiffgaffTesco Mobile

How easy is it to switch networks?

If you want to switch networks to find a better deal, you first need to find out how long is left on your existing contract.

If you're approaching the end of your contract, your network is now obliged to send you an end of contract notification.

Once you're out of contract, switching networks is as simple as sending a text thanks to the introduction of the text-to-switch legislation.

Women comparing SIM only deals

Can I trust smaller networks? Is the service as good?

Although the likes of giffgaff and VOXI aren't as instantly recognisable as high-street names such as Three and Tesco Mobile, they're certainly brands you can trust.

In fact, many smaller networks offer market-leading call rates and data deals, so they can often work out cheaper than more well known networks.

You'll also find that there's no difference in call quality and mobile internet coverage with smaller providers.

That's because their service is based on larger providers' network infrastructure, which these smaller networks pay a fee to use.

Where you may find a difference compared with the larger networks is in customer support.

In order to keep prices low, some smaller networks don't operate a call centre and offer online support only.

If you choose smaller networks you also shouldn't expect enticing customer incentives, such as O2's Freebies or movie downloads with EE.

But you may decide that you don't want or need those and that a good service and cheap rates are your priority.

I've found a SIM only deal with another network. What do I do next?

The next thing to do is make sure you're not still under contract and are free to switch. The best way to do this?

  • Ring your network

  • Contact your new network - Once you’ve made sure you're able to switch, contact your new chosen network and sign up for for the new deal. You'll then get your new SIM card in a couple of days.

  • Contact your current network - Don't forget you'll also need to ring or email your current network to let them know you’d like to leave. If your phone is locked, they will need to unlock it.

  • Be clear - Your network will probably try to keep you on board and you may find yourself being passed on to its customer retentions department. If this happens, just make sure you're firm and clear over your desire to switch.

  • Pop in your new SIM - You may have to pay charge to unlock your phone. But this should be pretty small, maybe around £15-£20. And once the phone is ready and unlocked you can pop your new SIM in and get started with your new plan.

  • Request your PAC code - If you want to keep your current number, which is always handy, you'll need to request your PAC code (Porting Authorisation Code) when you tell your network you are leaving.

Will I lose service if I switch to a SIM only deal with another network?

Moving networks is meant to be a near-seamless process so you're hardly ever out of service.

You'll still be able to take calls and receive texts after you've given your new network your PAC code (see above for more about PAC codes).

When the actual switch to your new network happens, you may lose service for a very small period of time.

When the transfer is said to be done, just put your new SIM in to your phone and switch it on. If the phone works and you can make calls - you've got service and you're all set.

How can I tell if my phone is unlocked and will it accept another network's SIM?

A locked phone means you can only use it on the network you bought it on, but this can differ depending on which network, handset and plan you have.


If you buy a phone with Vodafone, it'll be locked to its network. So if you want to switch over to another network's SIM, you'll have to unlock your handset first.


When it comes to O2 phones bought on pay monthly plans, you'll find that some are completely unlocked. But all pay-as-you-go phone from O2 are unlocked.


Three phones always come unlocked. Regardless of the type of phone, price plan it was bought on or if you got it on pay monthly contract or pay as you go plan.

Don't worry if you're a bit confused, it's all a bit complicated. However, there's a simple way to see if your phone is unlocked.

  • All you need to do is to take out your current SIM and put another network's SIM in to your phone. Just ask a friend or family member if you can borrow theirs for a quick test.

  • If your phone takes the SIM and it works like normal with a signal, this means your phone is unlocked and so it won't need to be unlocked at all.

  • But, if you can't get a signal, this means your phone is indeed locked. You'll then have to call your network to ask them to unlock your smartphone which may incur a payment.

For more info on switching networks, check out our handy guide.

My phone is unlocked. What's my next move?

Great, that's good news. You're now free to get a new SIM. The next thing to do is find a SIM only deal that suits your needs.

The best way to do is that by using the Uswitch comparison tables above. For some guidance as to which network to choose, take a look at all networks that picked up prizes at the 2022 Uswitch awards in the section below.

I've found a good SIM only deal with my existing network. What happens now?

If you're out of contract, you're free to sign up to another deal. However, if you want to stay with your existing provider, you'll need to speak to them to make sure you can move to a new deal and keep your current phone number.

If you're upgrading your contract with your current provider, it should be really straightforward to switch to a new deal and keep your number. But, if you've found the deal via a third-party, like Uswitch or another price comparison website, you'll need to check with your network that it can switch your number for you.

How do I keep my number when I get a new SIM?

So you've found a new SIM only deal, but if you want to keep your number when you change networks, you'll need to ask for a PAC code from your current provider.

A PAC code is made up of three letters and six numbers and is provided free by your network.

Previously, getting your network to part with your PAC code would involve phoning or emailing your network or even filling out a PAC code request form.

But now, thanks the recent introduction of 'text to switch', getting your PAC code is as easy as sending a text message.

  • All you have to do is text PAC to 65075, and your network provider is required to send your PAC code in a text reply as soon as possible, you may even get it right away. You'll also receive important info regarding any charges, costs or outstanding balances you may have.

  • In the meantime, leave your old SIM in your phone. This means that apart from a very brief period when the transfer is actually underway, you’ll still be able to receive calls and texts on your phone.

  • To check if the transfer is complete, just insert your new SIM in your handset and see if your new number is registered on your new network. If you are, everything's gone according to plan.

Find out more about keeping your number when you switch network.

How do I go from contract to SIM only?

If you’re still on a mobile phone contract you’ll have to wait for the plan to end before you switch over to SIM only, unless you’re willing to pay a cancellation fee. But when your contract is up, signing up to a SIM only plan is as easy as letting your network know you’re keen to switch with a simple text, and then finding a SIM only plan that suits your needs.

When will my new SIM only contract start?

Your new SIM only contract will start as soon as you receive the SIM card. Once you’ve signed up to a plan on your chosen network and deal, you’ll quickly receive a SIM card in the post. All you need to do is pop the SIM into your mobile phone and you’ll be ready to go.

Find out more about keeping your number when you switch network.

Ru Bhikhaquotation mark

If you’re nearing the end of your contract, you could reduce your bill dramatically by switching to a SIM only plan as you’ll no longer pay extra for a handset.

If you’re happy with your current phone or bought a device outright, SIM only offerings give you more opportunity to tailor your package - whether you’re a data guzzler or prefer to keep things minimal.

Plenty of SIM only offers have no contract, allowing consumers to hang on to their handset for as long as they like and choose the right time to upgrade.”

Ru Bhikha, Mobiles Expert
Man scrolling SIM only deals

What do I do with my old SIM?

Data theft is a big worry these days, and if you're concerned that your SIM and all the info on it - contacts, text messages, personal information - could fall into the wrong hands, you'll need to dispose the SIM card with due care.

Just like a bank card, the best thing to do is chop the SIM card up with a pair of scissors.

While you're destroying the card make sure you cut through the gold foil so its absolutely corrupted and there is no way anybody can get any info off the SIM. then just through the pieces in the bin. Job done.


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