THE best SIM-only deals are a no-brainer if you're looking for a budget-friendly way to own a smart phone.
With modern mobile phones living longer than ever before, buying a SIM-free, second-hand or refurbished handset and combining it with a SIM-only plan is one of the quickest and easiest ways to vastly reduce your smartphone bill.
What is a SIM-only deal?
SIM-only means you're purchasing a SIM card, without a handset, which can be paired with an unlocked phone. The SIM card carries your phone number, contacts list, and text messages, making it easy to swap to a new phone.
There are a huge number of cheap SIM-only deals on the market from all of the biggest carriers and the key is finding the deal that most closely suits your needs.
The best SIM-only deals will match your level of usage in minutes, text messages and data. SIM-only plans vary in what they offer, and for what price, so it's worth shopping around to find a good deal for your requirements.
Many also offer additional perks and extras to lure new customer in, or have exclusive deals for existing customers.
While many SIM-only deals are available on a rolling month plan, which you can cancel at any time, others are 12-month or longer contracts, which you are tied to, unless you want to pay cancellation fees to switch.
To help you compare the best SIM-only deals from all major networks, we've included a wide variety of price plans and data limits, so it's simple to see what's available.
*Prices in this article are correct at the time of writing but are subject to change. Shop around before you buy a SIM-only contract to ensure you're getting the best price.
Best Lebara SIM-only deals
Lebara specialises in short-term contracts with bundles including international minutes to 41 countries. Most bundles include 100 international minutes as standard, with the £30pm package including unlimited international minutes. Lebara runs on Vodafone's network.
- 3GB data, £5 a month - buy here
- 15GB data, £10 a month - buy here
- Unlimited data, £25 a month - buy here
Best Smarty SIM-only deals
Smarty runs on Three's mobile network and boasts some of the best value short term SIM-only deals around. The company also offers data discount plans that give money back for unused data.
- 12GB data, £8 a month - buy here
- 100GB data, £12 a month - buy here
- Unlimited data, £20 a month - buy here
Best Voxi SIM-only deals
Voxi gives its users unlimited social data, which means you can use Snapchat, Instagram, and WhatsApp without eating into your data allowance. Voxi runs on Vodafone's network.
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Best Three SIM-only deals
Three has some good value long-term contracts, which get you a lot of data for your money, but without the flexibility of a short-term contract. Most Three deals also include 5G ready data.
You can find all the best Three SIM-only deals in our round up, some of which have cashback offers.
Unlike most carriers, Three's SIM-only plans allow users to create a personal hotspot, the usage of which is taken from the monthly data allowance.
Three's Advanced Plans are also worth a look – available as pay monthly or SIM-only plans, they're all-inclusive deals that include minutes, texts and data, plus premium extras, including free roaming, free Wi-Fi on the London Underground and support for 4G Super-Voice.
- Unlimited data, £11 first 6 months (£22 after), 24-month contract - buy here
- 100GB data, £16 a month, 24-month contract - buy here
- 30GB data, £7 first 6 months (£14 after), 24-month contract - buy here
Best Vodafone SIM-only deals
Vodafone's SIM-only deals are packages of 4G and 5G data, minutes and texts, many of them coming with various roaming options. The company is now offering several unlimited data plans, each offering different download speeds. Below we've rounded up some of the best of them.
- Unlimited data (4G), max download speed 2Mbps, £23 a month, 24-month contract - buy here
- Unlimited data (4G), max download speed 10Mbps, £27 a month, 24-month contract - buy here
- Unlimited data (5G), average speeds of 150-200Mbps, peak speeds above 1Gbps, £32 a month, 24-month contract - buy here
Best O2 SIM-only deals
O2 has competitive prices and very good 4G coverage across most parts of the UK, so getting a SIM-only contract with them will mean you'll get a good signal wherever you are.
Being part of O2 means you can enjoy VIP perks on O2 Priority, which includes treatments, discounts, freebies and prize draws.
The company also offers bundles including six months of Disney+ or three months of Amazon Prime Video, Amazon Music Unlimited, Audible, Calm, McAfee & others to help you save on video and audio streaming services.
- 150GB data + 6 months of Disney+ or up to 12 months of another Extra, £24 a month - buy here
- 250GB data + 6 months of Disney+ or up to 12 months of another Extra, £28 a month - buy here
- Unlimited data + 6 months of Disney+ or up to 12 months of another Extra, £32 a month - buy here
Best EE SIM-only deals
Being an EE customer means enjoying excellent coverage and fast speeds across the UK as they're a step ahead of most rival networks. You can even check your coverage on EE's website before you commit, so you can be sure you'll always have the signal you need. All of EE's SIM-only deals include unlimited minutes and texts, as well as 4G and 5G options.
- 1GB data (5G), £14 a month - buy here
- 150GB data (5G), £20 a month - buy here
- 200GB data (5G), £23 a month - buy here
Best Sky SIM-only deals
When it comes to mobile networks, Sky's Piggybank is one of the best rollover schemes you can find. Get any unused data back into your wallet for you to use whenever you like to either top up your data or cash in for a range of rewards.
Best iD Mobile SIM-only deals
iD Mobile is a good value network that doesn't offer many extras but has competitive prices and a good range of both long-term mobile contracts and SIM-only plans. The company regularly offers discounts, so it is worth checking often to make sure you get the best deals.
Best giffgaff SIM-only deals
Giffgaff is one of the smaller mobile networks in the UK, but the company is growing in popularity, thanks to its flexible plans and quite affordable prices. Giffgaff's coverage relies on the O2 network, so you can rest assured you'll get solid coverage in most parts of the UK.
- 15GB data, £10 a month - buy here
- 30GB data, £15 a month - buy here
- 100GB data, £20 a month - buy here
- Unlimited data, £35 a month - buy here
Best Tesco SIM-only deals
Tesco Mobile is very highly rated amongst its customers, with recent industry data from Ofcom suggesting 97% of Tesco Mobile customers were satisfied with the overall service.
The company offers excellent value for money when it comes to both SIM-only and handset deals, with extra benefits for Clubcard holders.
- 30GB data, £12.50 a month (£12 Clubcard deal only) - buy here
- 60GB data, £15 a month - buy here
- Unlimited data, £20 a month - buy here
BT SIM-only deals
Best known as the UK's biggest home phone, TV and broadband provider, BT also offers a decent range of SIM-only deals and all of them include unlimited minutes and texts.
Plus if you're an existing BT broadband customer, there are exclusive deals available that will save you serious pennies.
BT runs on EE's excellent network, offering some of the widest coverage available, so you can be confident you'll never be out of range either.
- 4GB data, £13 a month (24 month contract) - buy here
- 10GB data, £15 a month (24 month contract) - buy here
- 100GB data, £25 a month (24 month contract) - buy here
What are the benefits of SIM-only deals?
The main benefit of getting a SIM-only contract is flexibility. Instead of being locked into a two-year contract like you are with most phone providers, you can easily snap up a rolling-one month deal that's easy to walk away from (although longer contracts are available).
SIM-only deals are particularly useful if you're buying second-hand and refurbished phones; the combination between a cheap handset and a good value SIM-only contract means you can pay much less for the same package than you'll ever be offered in a store.
What are the drawbacks of SIM-only deals?
If you don't already own a good smartphone, a SIM-only deal could end up being frustrating, as you won't have a proper device to make the most out of your data deal, for example. In cases like this, you could end up saving some money by getting a phone contract, particularly if you're in the market for the latest phones. In addition, before getting a SIM-only deal, make sure your phone is unlocked, as if it isn't, you won't be able to use your new SIM card with it.
How can I tell if my phone is unlocked?
If you have an iPhone updated to iOS 14, it is very easy to check if your device is unlocked. Simply go to ‘Settings’, then ‘General,’ and finally tap ‘About.’ You will see a ‘Carrier Lock’ setting there. If it shows ‘No SIM Restrictions’, your phone is unlocked, otherwise, there will be the name of a network service provider there, showing that your iPhone is locked to that particular carrier.
With Android phones, the situation is a little bit trickier, as there's no way of checking if the device is locked via the settings. Instead, what you can do is simply try a SIM card from a different carrier. If you're able to make phone calls and access the mobile network after the switch, your phone is unlocked. If you can't, it is locked.
Which mobile network is best?
According to uSwitch, EE offers the UK's widest and fastest 4G coverage, with a whopping 99% of the UK covered. O2 is a close second, with its 3G/4G connection covering 99% of the country, though speeds are generally a little bit slower than EE's. Three, Vodafone, and iD Mobile are also valid options, all with coverage rates above 90% nationwide, and in many parts of the UK, fast speeds.
Additional mobile networks with solid coverage are Tesco Mobile, GiffGaff, Talkmobile, and Sky Mobile, together with Smarty, which uses Three's 4G network.
In terms of 5G coverage, the technology is still patchy across the UK, but Vodafone and EE are at the forefront of the technological race here, with speeds faster than any other mobile network provider.
Can you cancel a SIM-only contract?
Yes, you can, but you probably shouldn't. Many companies charge an early termination fee, which can be quite costly. As a rule of thumb, the early termination fee amounts to the summed, monthly fees left on your contract at the time of cancellation. So, for example, if there are ten months left in your £10-a-month contract and you want to cancel now, you will have to pay £100.
Of course, some SIM-only deals are just so amazing that missing them may cost you more in the long run, so at the end of the day it boils down to calculating the overall advantages of cancelling an ongoing contract vs starting a new, cheaper one.
Is it easy to switch mobile phone networks?
Yes, it is. All you have to do is to wait out until your current contract expires (to avoid paying cancellation fees), then switch provider.
In order to do that, just go on the website of your chose courier and complete the registration process. A SIM card will then be posted to your address, ready to be activated.
I've found a SIM-only deal with a different network, what do I do now?
Generally speaking, it is convenient to wait for your current contract to end before starting a new one, to avoid cancellation fees. However, if you found a deal that is absolutely unmissable (or you don't mind paying the cancellation fee), you can simply start a new contract with them, and cancel your current one.
How do I keep my phone number when I switch networks?
If you're ending your existing contract and want to keep your number while moving onto another network's SIM-only deal you can. You'll need to contact your existing provider and request a PAC code. A PAC code will be used by your new network to register your number on their service.
However, if you're moving to a SIM-only deal on the same network you may have to change your number.
What do I do with my old SIM?
If you migrate your old number to a new SIM card, you can destroy the old one, as it will be deactivated the moment the number is transferred. If you start a new contract with a new phone number, however, your old SIM will stay active for a while. In that case, you may want to keep your old SIM, if you intend to use it again.
Just a heads-up, if you have any credit left in your old SIM card, you may want to use it, as if left unused, it may expire after six or 12 months.
Will a SIM-only deal improve my credit rating?
Potentially, yes. Whether or not the provider will run a credit check on you, a SIM-only contract will involve a credit agreement. Because of this, you could build up your credit rating by keeping up with your monthly, SIM-only contract payments.
Will there be a credit check when I apply for a SIM-only deal?
Legally speaking, there's no minimum credit score needed to get a phone contract, but some companies will run a check anyway. Different network operators will also score you differently, so if you can't get a contract with one, you could try checking with others.
For context, 30-day rolling SIM-only contracts do not usually require credit checks since they are extremely low risk to the company. However, if you're signing up for a 12 or 24-month SIM-only contract, it is more likely that they will check your credit score.
Which network has the best SIM-only deals?
Here's a selection of mobile phone networks which have great SIM-only deals:
How much data should I look for in a SIM-only deal?
To find out how much data you use each month, simply log into your account with your provider, check how much data you use each month, and buy a SIM-only plan accordingly.
Some SIM-only providers, such as Voxi, offer unlimited social media data too, which means you might get through a little less data than normal. If you burn through data very quickly, some providers, such as Smarty, offer unlimited data packages for as little as £18 a month.
Should I get a 30-day or 12-month SIM-only contract?
You'd think companies would try and lure customers in by giving them lower prices on 12-month SIM-only contracts, but that's not necessarily the case. After examining comparable SIM-only contracts on price comparison sites, we've noticed there's much correlation between the length of a contract and lower prices.
The decision to get a short-term or a long-term SIM-only contract should be made on a case-by-case basis.
What size SIM card do I need?
There are three sizes of SIM cards available: standard, micro, and nano. The size you'll need depends on your phone and should be made clear in your handset's instruction manual.
As a rule of thumb, iPhones tend to take nano SIMs, Samsung Galaxys take micro SIMs and standard SIM cards have been relegated from the mainstream altogether.
How do I change my SIM card?
Each phone will have a different method for changing the SIM card. Head to the brand's website to find out how to swap yours:
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