Best SIM only deals
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Basics SIM Only30GBdataUnltdminutesUnltdtexts12month contractZeroupfront cost£8.00per month(monthly price + out of bundle charges will increase every April by the Consumer Price Index rate of inflation + 3.9%)Visit NowVodafone
SIM Only£20 Amazon Gift Voucher when you refer a friend30GBdataUnltdminutesUnltdtextsNo contractZeroupfront cost£10.00per monthVisit NowVoxi
Smarty UnlimitedUnltddataUnltdminutesUnltdtexts1month contractZeroupfront cost£16.00per monthVisit NowSmarty
Big Bundle 25GBO2 TravelFree EU Roaming25GBdataUnltdminutesUnltdtextsNo contractZeroupfront cost£15.00per monthVisit NowO2
Smarty 6GB6GBdataUnltdminutesUnltdtexts1month contractZeroupfront cost£5.00per monthVisit NowSmarty
goodybag 1GBFree EU Roaming1GBdataUnltdminutesUnltdtextsNo contractZeroupfront cost£6.00per monthVisit Nowgiffgaff
5G SIM Only 50GBFree EU RoamingFree Roaming up to 30GB50GBdataUnltdminutesUnltdtexts1month contractZeroupfront cost£8.00per monthVisit NowiD Mobile
5G SIM Only 25GBFree EU RoamingFree Roaming up to 30GB25GBdataUnltdminutesUnltdtexts1month contractZeroupfront cost£7.00per monthVisit NowiD Mobile
5G SIM Only 70GBFree EU RoamingFree Roaming up to 30GB70GBdataUnltdminutesUnltdtexts1month contractZeroupfront cost£10.00per monthVisit NowiD Mobile
Big Bundle 8GBFree EU RoamingO2 Travel8GBdataUnltdminutesUnltdtextsNo contractZeroupfront cost£10.00per monthVisit NowO2
Lite SIM Only 3GB3GBdataUnltdminutesUnltdtexts24month contractZeroupfront cost£5.00per month(prices may change during contract)Visit NowThree
Lite SIM Only 3GB3GBdataUnltdminutesUnltdtexts12month contractZeroupfront cost£5.00per month(prices may change during contract)Visit NowThree
5G SIM Only 8GBFree EU RoamingFree Roaming up to 30GB8GBdataUnltdminutesUnltdtexts1month contractZeroupfront cost£6.00per monthVisit NowiD Mobile
5G SIM Only 8GBFree EU RoamingFree Roaming up to 30GB8GBdataUnltdminutesUnltdtexts24month contractZeroupfront cost£6.00per monthVisit NowiD Mobile
5G SIM Only 8GBFree EU RoamingFree Roaming up to 30GB8GBdataUnltdminutesUnltdtexts1month contractZeroupfront cost£6.00per monthVisit Nowe2save
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How to get the best SIM only deal

In this guide

  1. What is a SIM only deal?
  2. Why get a SIM only deal?
  3. How does SIM only work?
  4. Which providers offer SIM only deals?
  5. Types of SIM card
  6. Keeping your existing phone number
  7. Frequently asked questions

There are a number of things you'll want to consider when choosing a SIM only deal. Your first consideration should be your choice of network and provider. There are four mobile networks in the UK – Vodafone, Three, EE and O2 – and all other providers operate on one of these four.

Next, you should consider whether you want a pay monthly or pay as you go (PAYG) SIM, and in the case of pay monthly, whether you are after a rolling 30-day contract or looking to sign up to 12 months or more. Once you have these choices in mind, you can then use our comparison tools (above) to find a SIM deal within your budget and with an amount of data, minutes and texts that suits your needs.

We have a treasure trove of information to help you decide further down this page, but first let's cover the basics.

What is a SIM only deal?

Mobile plans come in a few different flavours. The type most of us are familiar with are pay monthly plans that include a handset. With these type of plans you'll be paying for your services – minutes, data, texts – and on top of that pay monthly instalments for the hire-purchase of your new handset.

SIM only, as the name suggests, is just a SIM, just the services without a handset. You simply put the SIM in your existing handset and, provided your phone isn't locked to another network, off you go. There are short and long pay monthly contracts, or there are pay as you go (PAYG) SIMs which can work out even cheaper to those with minimal usage.

Why get a SIM only deal?

Pros

  • Keep your current handset – New handsets are the single most expensive overhead on a traditional pay-monthly with handset deal. Apple now has a phone costing a frankly insane £1,500, but the truth is these flagship phones really don't do all that much that older models don't. Keeping your existing handset is smart, so long as you don't always just have to have the latest thing
  • They're cheaper – Because you're not paying for a handset on top of your services, SIM only deals are always much cheaper
  • Shorter contracts – Most pay monthly handset deals will tie you in for two years or more so as to cut the considerable cost of the handset into smaller chunks. SIM only deals are 12 months maximum, with a great deal of them on 30-day rolling contract
  • Wider choice of networks – All mobile providers offer SIM only deals, but not all of them offer deals with handsets. By choosing SIM only you widen the field of potential new providers

Cons

  • You may need to unlock your phone – If you got your handset through another provider rather than simply buying it outright, your phone may be locked to that provider. You therefore may have to unlock your phone before you can install your new SIM. Unlocking your phone is easy, however
  • Maybe you want that ultra-high-end handset – If you really want the latest flagship phone from Apple or Samsung, a SIM only deal along with buying the handset outright is not the best way to do it. Unless you're Richy Rich, that is – in which case fill your boots

How does SIM only work?

There are two types of SIM only deal: Pay monthly, which is itself divided into 12-month contracts and one-month (30-day) rolling contracts. And pay as you go, commonly abbreviated to 'PAYG'.

Pay monthly

With a pay monthly SIM only deal, you will sign up to either a 30-day rolling contract, which you can leave at short notice, or a 12-month contract which you will be tied into for the entire period. Both have the advantage of being able to pay by direct debit. In return for your commitment, 12-month contracts are often cheaper and/or offer more minutes texts and data.

Pay as you go (PAYG)

With a pay as you go SIM deal, you'll pay up-front amounts of your choosing, topping up as and when you need to. Keep in mind that most PAYG deals have a fixed expiry on the minutes, texts and data you buy, often as little as 30 days. You cannot, therefore, purchase a tenner's worth of credit and eke it out over several months. There are a few select PAYG deals with a long expiry, so if this is your plan, you should check these out first.

Advantages of a pay monthly SIM over pay as you go

  • You can pay by direct debit – Whether choosing a 30-day rolling contract or something more long term, a pay monthly SIM is a greater commitment to your provider than a free PAYG SIM, which you can pick up just about anywhere and dispose of whenever you please. For this reason, most pay monthly SIM deals will allow you to pay via direct debit
  • Your credit won't expire – Pay monthly SIM deals offer a defined amount of minutes, texts and data which will refresh each month. Which is expiry in a way, but only at the exact same moment it's fully topped up. Unless you're frequently exceeding your allowances, this means it's a lot less hassle. If you are doing that, mind you, you're probably on the wrong deal
  • More of everything for less money – Like it says. Better value, in essence.

Advantages of a PAYG SIM over pay monthly

  • No credit checks – Pay monthly SIM only credit checks are far less demanding than deals involving expensive handsets. That said, if your credit rating won't stand up to any sort of scrutiny right now, a PAYG SIM deal is probably the way to go. No credit checks at all
  • Only pay for what you use – If you get your top-ups just right you may find yourself paying for exactly what you use and no more. However, this ideal is rarely achievable in real life, and in terms of value for money, you're always going to be worse off with PAYG
  • Can be cheaper in some instances – If you manage your credit carefully – and we mean you get it exactly right in terms of the credit you spend during each expiry period – you may just end up paying a little less. We think it's unlikely, though, and PAYG deals should really only be considered by those who are certain they won't pass a credit check

30-day or 12-month contract – which is best for you?

Pay monthly SIM only deals come in just two flavours: Those on a 30-day rolling contract and those that will tie you in for 12 months. How do you choose between them? Here's how.

Choose a 30-day contract if…

  • You're passing time till your next handset upgrade – 30-day rolling contract SIMs are great time fillers if you know that a few months down the line you're going to switch again and pick up that handset upgrade you have your eye on
  • You're not 100% sure about the provider – Sometimes you'll see an ultra-cheap or appealing deal from a provider you've never been with before, but you're not sure about its coverage, customer service and so on. A 30-day rolling contract can be a good way to try it out
  • You can't commit to 12 months – For whatever reason – maybe you're leaving the country – you can't commit to a 12-month contract

Choose a 12-month contract if:

  • You want the cheapest SIM possible – SIM deals on 12-month contracts are almost always cheaper than one-month rolling contract deals. For your commitment to the longer term, you get something in return: cheaper prices and/or more minutes, data and texts
  • You're not 100% sure about the provider – Sometimes you'll see an ultra-cheap or appealing deal from a provider you've never been with before, but you're not sure about its coverage, customer service and so on. A 30-day rolling contract can be a good way to try it out
  • You can't commit to 12 months – For whatever reason – maybe you're leaving the country – you can't commit to a 12-month contract

Which providers offer SIM only deals?

Pretty much every mobile provider in the UK offers SIM only deals. At Cable.co.uk, we don't list every provider because we consider new, unproven and/or minuscule providers with a tiny customer base too risky to recommend. They go out of business all the time. Here are the SIM only providers we do stand behind.

  • Sky Mobile – Offers a small-ish range of handset and SIM only deals with discounts for Sky broadband and TV customers. Sky Mobile is on the O2 network, and all of its contracts are 12 months
  • BT Mobile – Has SIM only deals to suit any need and any budget, and offers some great discounts on its 'Family SIM' deals – where you get additional SIMs for other family members at a reduced price. BT Mobile is on the EE network, and of its SIM contracts are 12 months
  • Virgin Mobile – Has both SIM only and pay monthly handset deals – low cost and with whopping amounts of data for relatively little money. Virgin Mobile is on the EE network and all of its contracts are 12 months
  • EE – Is the UK's most popular network. As you'd expect, EE will sell you just about anything mobile-related, from SIM only and handset deals to data SIMs for tablets and more. EE is on its own network (naturally), and all its contracts are 12 months long
  • Three – As one of the UK's four network providers, as you'd expect Three offers just about everything. It's on the Three network, of course, and all of its SIM only contracts are 12 months long
  • Plusnet Mobile – Plusnet offers some decent SIM only deals, but due to the fact that all of its contracts are flexible 30-day affairs you won't get as much for your money as if you're able to commit to another provider for 12 months. Plusnet Mobile is on the EE network
  • Tesco Mobile – The supermarket giant offers both pay monthly handset and SIM only deals on both 30-day and 12 month contracts. Something for everyone. Tesco operates on the O2 network
  • Vodafone – Vodafone is one of the UK's four network providers. It offer everything under the sun, operating – naturally – on its own network. Vodafone offers both 12-month and 30-day SIM deals
  • O2 – O2 is another of the UK's four network providers. It offers pretty much anything you could possible want, from SIMs to handsets, tablet data SIMs, mobile broadband dongles and more. It operates on its own network and offers both 30-day and 12-month contracts
  • giffgaff – Yes, with a lower-case 'g'. It's a rather unique provider thanks to its community-run customer service. It's owned by O2 and operates on its network. It only offers rolling 30-day contracts on its SIM only deals
  • Asda Mobile – Unlike supermarket competitors Tesco, Asda only offers SIM only deals. Some of the cheapest out there, in fact. Asda Mobile operates on the EE network and all of its contracts are rolling 30-day affairs

Types of SIM card – which do you need?

Depending on your handset, you will need one of three different sizes of SIM card. It's a good idea to know which you need before ordering your new SIM.

  • Standard – 15mm x 25mm in size, this is the largest of the three. You only generally find standard SIMs in older models of tablet, and some laptops. It's unlikely your phone requires one
  • Micro – 12mm x 15mm in size, this is where is gets trickier. Luckily, though, most providers will supply you with what's known as a dual-cut or triple-cut SIM, which encompasses both sizes – you just need to press out the smaller from the larger
  • Nano – 8.8mm x 12.3mm in size, most new phones, especially the higher end ones, use a nano SIM. As mentioned above, it's unlikely you'll get the wrong one as most providers these days will send you a dual or triple-cut SIM

Keeping your existing mobile phone number

Switching your mobile provider once your contract has ended is very straight-forward. Of course, you will keep your existing number when switching unless you actually need a new one. Generally speaking, you will follow these steps.

  • Request a PAC code – You just need to call your provider, or in some cases you can do this online. They will give you something called a PAC code – stands for porting authorisation code
  • Get on your new network – Once you have your new SIM, put it in your phone. You will have a new number at this point, but fret not. Phone your new provider and give them your PAC code
  • Wait 48 hours – That's it! Within 48 hours, but often much sooner, your new SIM will be registered with your old phone number

There are a number of things you'll want to consider when choosing a SIM only deal. Your first consideration should be your choice of network and provider. There are four mobile networks in the UK – Vodafone, Three, EE and O2 – and and all other providers operate on one of these four.

Next, you should consider whether you want a pay monthly or pay as you go (PAYG) SIM, and in the case of pay monthly, whether you are after a rolling 30-day contract or looking to sign up to 12 months or more. Once you have these choices in mind, you can then use our comparison tools (above) to find a SIM deal within your budget and with an amount of data, minutes and texts that suits your needs.

We have a treasure trove of information to help you decide further down this page, but first let's cover the basics.

Go back to deals

Frequently asked questions

How do I change my SIM card?

It varies from handset to handset. With most new handsets you will find a small hole somewhere around the edge of your phone. Use a pin or the special tool supplied with your phone to press into the hole and pop out the SIM drawer. Take out the old one, put in the new one, close the drawer and Bob's your uncle.

Can I get a SIM only deal for my tablet?

Yes. The big four network providers all provider data SIMs specifically aimed at tablet users.

What if I fail my credit check?

If you fail a SIM only credit check, your credit rating is in a bad way. Sorry about that, we've been there and it's tough. Instead of a SIM only deal you should consider a PAYG SIM instead.

Can I trust smaller, less well-known mobile providers?

Yes and no. While there is generally little wrong with the service you receive from smaller providers, the smaller the provider the less stable it tends to be. New providers come and go all the time, often leaving their customers high and dry. At the very least you should consider a provider that's been around long enough to build a reviewable track record – a few years at least.

Will I lose mobile phone service when I switch? For how long?

Almost never. There may be a small window of a few hours, a day at most, when you're waiting for your PAC to activate your old phone number on your new phone, but this is going to be as a result of some sort of error in the process. For the vast majority it's seamless.

Are SIM only deals cheaper?

Yes. Always. If you're getting a handset in the deal, and it's at least a reasonably modern one, you'll be paying for it in instalments on top of your monthly charges for your services. Without a handset you just pay for the services.

Can I just put a new SIM in my phone or do I need to unlock it first?

If your phone is locked to one provider and you want to switch then yes, you will need to unlock it first. The easiest way to find out if your phone is locked is to borrow a SIM for a couple of minutes from a friend or family member who is on a different network. If you get signal, you're golden, if not, you may need to get your phone unlocked.

How much mobile data do I need?

Most of us spend a most of our time close to a wifi signal. In which case you probably need less data than you think. If you don't download apps using your data allowance or watch video, you probably need very little. 2-4GB may do you fine, maybe even less. However, if you're always using online apps when you're out and about, commonly watching video on YouTube and the like you're going to need a lot more.

What's the best mobile network?

It changes from year to year. To see the provider we rate as the best this year, read our dedicated guide on the best mobile network.

Which networks have good coverage/signal where I live?

There are four actual network providers in the UK: Vodafone, EE, Three and O2. All other providers use one of these four networks. Therefore, to get an idea of the signal you're going to get where you live, you should visit each of the four and look up signal strength in your locale using their maps.

Can I get 4G on SIM only?

Yes. It's actually hard to find any 3G SIM deals anymore these days. 4G is the norm.

How long does it take to switch?

Around a week. Once you've ordered you'll need to wait (up to 5 working days) to get your new SIM in the post. Once you have it – and in the meantime got your PAC code form your existing provider – it will take another 48 hours to switch the SIM to your old number.

Can I upgrade a SIM only deal?

Yes. Once you have the SIM, if you need more minutes, texts or data and you want to upgrade, you can do this with either a phone call to your provider or in many cases, just log into your online account and tick a box or two. You won't need a new SIM and the upgrade is usually instantaneous.