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The best SIM only deals in April 2021

By Cable.co.uk | Friday, February 5th 2021

A SIM only deal is a SIM card (the tiny chip that slots inside your phone and connects you to the network of your choice) and the mobile phone package that comes with it, no handset included. Sounds simple, right?

In reality, there are a number of things to consider when choosing a SIM only deal, including which provider to go with, the type of deal (pay monthly or pay-as-you-go), whether you want an unlimited or restricted call package and the length of contract you want to commit to.

This page will help you find the right SIM only deal for you, and will show you some of the best SIM-only deals on the market from some of the UK’s most popular providers.

What is a SIM only deal?

Perhaps you love the handset you’ve got and you’re not quite ready for a new one – a SIM only deal provides you with a SIM card for calls and data and that’s all. You only pay for the calls and data, which can save you loads on your monthly bill.

You have a few choices when it comes to contracts: no contract (top-up), a 30-day rolling contract, or a range of longer contract terms including 12, 18 and 24 months.

SIM only deals can include unlimited data and calls, or a pre-agreed set of data limitations. They can also operate on a pay monthly or a pay-as-you-go basis.

Best PAYG SIM only deals

EE mobile
EE £10 Pack
  • 4GB data
  • 100 minutes
  • Unlimited texts
  • Data rollover
  • Top up anytime
  • Free data boosts
£10.00
min top up
See Deal
O2 Mobile
O2 Big Bundle 6GB
  • 6GB data
  • Unlimited minutes
  • Unlimited texts
  • Data rollover
  • Top up anytime
  • 4G ready
£10.00
min top up
See Deal

A Pay-as-you-go (PAYG) SIM only deal, as the name suggests, means that you pay for the calls, texts and data you use, rather than these being included in a monthly package.

There are two types of PAYG deal:

  • Traditional PAYG, where you buy credit in advance to ‘spend’ on calls, texts and data as you use them.
  • PAYG in a bundle, which gives you a monthly allowance of calls, texts and data for a set price.

Using your phone is often more expensive on a PAYG basis, but you don’t have to worry about credit checks and you can change providers at any time, without incurring a penalty. The extra cost might be worth it for the flexibility.

If a PAYG SIM only deal sounds appealing, you’ll need to have your own handset or buy one separately to put your new SIM card in. Make sure you go for one that’s compatible with the right SIM card size and consider taking out insurance in case your handset is lost, stolen or damaged.

Compare PAYG SIM only deals

Best 30 day rolling SIM only deals

SMARTY mobile
SMARTY 30GB Plan
  • 30GB data
  • Unlimited minutes
  • Unlimited texts
  • 1 month plan
  • Cancel anytime
  • Fast 4G & 3G
£10.00
30 days
See Deal
VOXI Mobile
VOXI 12GB Plan
  • 12GB data
  • Unlimited minutes
  • Unlimited texts
  • Endless social media
  • No contract
  • Cancel anytime
£10.00
30 days
See Deal

A rolling 30-day SIM only deal is essentially a mobile phone contract that can be cancelled at any time, provided that 30-days’ notice is given to your provider. Also, you can increase or remove data from your plan if you find it’s not quite right.

Switching is pretty easy too. You only need to give a month’s notice, which means you can swap to a different provider if you see a better deal. As with all types of mobile phone contract, you should read the small print before signing on the dotted line.

Compare no contract SIM only deals

Best 12 month SIM only deals

Three mobile
Three Advanced SIM Only 12GB
  • 12GB data
  • Unlimited minutes
  • Unlimited texts
  • 5G ready
  • Personal hotspot
  • Go Roam
£8.00
per month
See Deal
iD Mobile
iD Mobile SIM Only Unlimited
  • Unlimited data
  • Unlimited minutes
  • Unlimited texts
  • Data rollover
  • Bill capping
  • Inclusive roaming
£16.00
per month
See Deal

A SIM only deal with a contract is usually the most cost-effective plan for a regular mobile phone user. Most networks offer more attractive rates for calls, texts and data usage if you’re prepared to commit to staying with them for a set period of time.

A typical SIM only contract lasts for 12 months, though some providers offer longer, shorter or rolling-contracts. If you find a provider that you trust and a deal that you like, signing up for a deal lasting a year should be great value.

Compare 12 month SIM only deals

Best 18 month SIM only deals

Tesco Mobile
Tesco Mobile SIM Only 15GB
  • 15GB data
  • 5000 minutes
  • 5000 texts
  • Half price offer
  • Available in 5G
  • 18 month contract
£12.50
per month
See Deal
O2 Mobile
O2 SIM Only 12GB
  • 12GB data
  • Unlimited minutes
  • Unlimited texts
  • 6 months of Disney+
  • 25GB for £3 extra
  • 18 month contract
£12.00
per month
See Deal

If you’re prepared to commit to a slightly longer contract term, some providers offer 18 month SIM only deals that should provide even better value than a 12 month contract.

Before signing up for this type of deal, think carefully about whether you can commit to staying with the same mobile phone provider for 18 months, and make sure you can comfortably afford your monthly payments over the contract term.

If you want to leave your 18 month SIM only contract part way through, it’s likely that you’ll be charged an early exit fee. These vary between providers, but can be quite hefty. As with any contract, familiarise yourself with the terms and conditions before signing up.

Compare 18 month SIM only deals

Best 24 month SIM only deals

BT Mobile
BT Mobile 5G SIM Only 100GB
  • 100GB data
  • Unlimited minutes
  • Unlimited texts
  • BT Sport app
  • 5G ready
  • BT Wi-fi access
£25.00
per month
See Deal
Virgin Mobile
Virgin Mobile £10 for 15GB bundle
  • 15GB data
  • Unlimited minutes
  • Unlimited texts
  • Data rollover
  • 4G speeds
  • Free messaging data
£10.00
min top up
See Deal

Generally, the longer you’re prepared to commit to a SIM only mobile contract, the more money you can save on your monthly payments.

24 months (2 years) is a long time to stick with one provider, but if you’ve found one you trust and are happy with the terms of service, you can enjoy cheaper monthly rates in return for your loyalty.

It’s worth checking whether you can add or remove elements of your service plan during the contract term, as your needs may change over 24 months.

Compare 24 month SIM only deals

Best unlimited SIM only deals

Three Mobile
Threee Advanced Unlimited Data
  • Unlimited data
  • Unlimited minutes
  • Unlimited texts
  • 12 month contract
  • 5G ready
  • Personal hotspot
£16.00
per month
See Deal
SMARTY Mobile
Smarty Unlimited
  • Unlimited data
  • Unlimited minutes
  • Unlimited texts
  • 1 month plan
  • Cancel anytime
  • No credit check
£16.00
per month
See Deal

Unlimited SIM only deals are ideal for people who never put down their mobile phones – whether they’re texting, calling, browsing the web or streaming content from sites like Amazon Prime, YouTube and Netflix.

If you need a limitless or large data allowance, look to big network providers like Three, EE, O2 and Vodafone. You’ve got a range of contract lengths available too – from PAYG to 24 months.

Compare unlimited SIM only deals

Best data only SIM deals

Three Mobile
Three Unlimited Data Only
  • Unlimited data
  • 0 minutes
  • 0 texts
  • 1 month plan
  • 5G ready
  • Global roaming
£26.00
per month
See Deal
Vodafone Mobile
Vodafone Data SIM
  • 2GB data
  • 0 minutes
  • 0 texts
  • 12 month plan
  • Global roaming
  • 3-in-1 SIM
£11.00
per month
See Deal

If you need a data only SIM deal to get online while on the go, using a device like a tablet, you can grab one of these through many of the major UK networks.

To make sure you have the right amount of date, you should work out how much data you’ll use each month.

If you’re out and about using your device every day – watching video content or download large files, 10Gb or more should do. If you mainly connect to WiFi and only use data to access the internet on your device every once in a while, a few GB will probably cover your monthly usage.

If you’re not sure, look for a plan that allows you to start with a low allowance and add data to this without incurring a penalty.

Compare data only SIM deals

SIM deals on each network

All of the UK’s major mobile phone networks offer SIM only deals. The provider that’s right for you depends on your individual needs and circumstances.

Here’s our run down of what you can expect from some of the biggest providers:

  • BT SIM only deals – BT has great discounts for existing BT Broadband customers and gives all SIM Only customers free access to the BT Sport app.
  • EE SIM only deals – With the fastest phone network in the UK, EE has some great extras for new SIM only customers, including discounts on fibre broadband and EE TV subscriptions.
  • O2 SIM only deals – The network offers 4G and 5G deals with incentives like exclusive offers from high street brands.
  • Three SIM only deals – Three is one of the only UK networks to offer truly unlimited data.
  • Vodafone SIM only deals – With Vodafone, you can enjoy unlimited data for three months with a 12 month contract. You can also access NOW TV, Spotify and Sky Sports mobile app with selected bolt-ons.

There are also a number of smaller, lesser known providers like giffgaff, Smarty and VOXI that provide SIM only deals. These can often be cheaper since they don’t operate within expensive high-street stores or pay for sophisticated customer service centres.

Frequently asked questions

Why choose a SIM only deal?

If your current mobile phone contract has come to an end and you love your existing handset, a SIM only deal could be a quick, efficient and cost effective way of getting network coverage.

Because you’re not covering the cost of a new handset within your monthly payments, you’ll spend less. These deals often come with unlimited or generous data allowances for less than what you’d pay on handset and contract plan.

How do SIM-only deals work?

A SIM only deal includes a SIM card and service from a mobile phone provider – no handset comes with the package.

SIM only deals can include unlimited data and calls, or a pre-agreed set of data limitations. They can also operate on a pay monthly or a pay-as-you-go basis with no contract, a rolling 30 day contract, or varying contract length of 12, 18 or 24 months.

Is a short-term deal better than a long-term deal?

It depends on your needs and circumstances. A no contract SIM only deal, or one with a rolling contract that can be cancelled at short notice, are great for offering freedom and flexibility. This comes at a price, however, as costs tend to be higher than with a long term contract.

Generally speaking, the longer the period you can commit to a SIM only deal, the lower your monthly payments should be.

Most providers will charge you an early-exit fee if you want to leave your SIM only contract part-way through, so make sure you can commit to the term you sign up for before signing on the dotted line.

How much data do I need?

How much data you need depends on how often you use your phone, and what you use it for.

On average, most of us need 2GB-3GB of data per month for general daily mobile phone usage.

If you only use your mobile phone to check your email or browse the internet, your requirements are on the lower end of the scale. If you regularly stream video, listen to music or podcasts, or use your phone for online gaming, you’ll need at least 3GB possible much more.

Your existing mobile phone provider should be able to tell you, quickly and easily, how much data you’ve been using – including a detailed monthly breakdown of what you use it for. With this information, you should be able to determine what kind of SIM plan you need – unless your usage is likely to go up or down dramatically in the near future, perhaps if you’re starting a new job or spending more time at home.

Are lesser known networks reliable?

While brands like giffgaff and VOXI are much less well known than high-street names like Three, EE and Vodafone, they’re worth taking into consideration when looking for a SIM free deal.

Smaller networks can sometimes offer cheaper call rates and data deals, as they don’t have to pay the big overheads that large brands do.

Where you’re likely to find a big difference between smaller and larger providers, however, is customer service. To keep prices low, some smaller networks don’t operate a call centre and offer only basic online support. Larger companies can provide the support to get you back on track quickly if something goes wrong.

With smaller brands, you’re also unlikely to be offered incentives like discounts on broadband provision, free movie downloads or savings on TV services. If you want a good, basic service with cheap rates, however, a smaller provider may meet your needs.

How do I switch networks?

If you want to switch mobile phone providers, you first need to check how long is left on your existing contract. If you’re only part way through, your network is likely to charge you an early-exit fee if you want to make a switch.

If your contract has come to an end, switching networks is easy. All you have to do is let your existing provider know that you won’t be renewing your deal.

Once you’ve chosen the deal you want, simply insert your new SIM into your existing handset when it arrives and you’ll be up and running in moments.

Will I lose service when I switch networks?

Switching phone networks is a quick and simple process, so you shouldn’t experience loss of service for a long period of time.

When keeping your existing number, you’ll be able to take calls and receive texts after you’ve been given your PAC code (see below for more information on this).

When the actual switch to your new provider takes place, you may lose service for a very short period. You’ll know the transfer is complete when you can put your new SIM into your phone, get network coverage, and make calls or send texts.

Your new provider should be able to give you full information on the switching process and whether you can expect any significant gaps in service.

What is an end of contract notification?

Mobile phone networks must now let their customers know when their mobile phone contracts are coming to an end. Knowing in advance when your contract is coming to a close will give you the opportunity to shop around for a better deal, should you wish to do so. It will also help you avoid you being automatically transferred onto a more expensive deal by your network.

When you receive your end of contract notification, make sure you start looking for new deals as soon as possible to give yourself time to find one you like.

How can I tell if my phone is locked or unlocked?

If your phone is ‘locked’ this means that it can only be used on the network you bought it on.

With some providers, such as EE and Vodafone, your phone will be automatically locked to their network. If you want to switch over to another network’s SIM, you’ll have to have your handset unlocked first.

With O2 phones bought on pay monthly plans, your handset may or may not be unlocked – whereas all PAYG phones from the network are unlocked, as standard.

Three phones are always unlocked, regardless of the type of price plan the phone was purchased on.

If you’re not sure, you can ask your current provider for this information. There’s also a simple way to find out if your phone is locked or unlocked. Insert your SIM card into a friend or family member’s phone who uses another network, and see if you can receive a signal.

If you want to unlock your phone, contact your network provider for assistance.

When buying a new handset, you can filter search results to only include unlocked phones, to prevent problems with switching networks in the future.

My phone is unlocked – can I switch networks?

Yes, if your phone is unlocked, you can insert a SIM card from any other network.

Can I keep my current mobile number?

If you want to keep your existing mobile phone number when you change networks, you’ll need to ask for a PAC code from your current provider. This is made up of three letters and six numbers, and should be texted to you free of charge from your existing network.

Rather than having to call your provider for a PAC code, you should now be able to request one by text message.

Simply text PAC to 65075 and your provider is required, by law, to send you your PAC code in a reply as soon as possible – often this happens instantly. You’ll also receive vital information about any charges, costs or outstanding balances on your account.

Your new network will need your PAC code in order to transfer your new number.

What do I do with my old SIM?

To avoid worries about data theft, you’ll need to dispose of your old SIM card carefully. As with an old bank card, the best thing to do is carefully chop it up with a pair of scissors, cutting through the gold foil section to completely corrupt the card (this way, nobody can take any information from it).

Make sure that you’ve transferred any information you want to keep hold of onto your new phone or another device, like photos, texts or videos.

Will a SIM only deal improve my credit?

Committing to paying a set fee for your plan each month over a long period of time will benefit your credit score in the long-term, as you’ll be showing lenders you’re trustworthy by paying on time each month.

Be careful though, if you miss monthly payments, you risk negatively affecting your credit score. If you’re worried about making monthly payments over a long period, a SIM only deal with no contract or a rolling contract that can be cancelled at short notice might be a better option, allowing you to cancel or downgrade at short notice with no issues.

What happens if I fail a credit check?

When signing up for a SIM only contract of any length, you will need to pass a credit check. For no contract or rolling monthly contract deals, a credit check is usually not required.

Some providers may consider taking you on as a customer even if you don’t pass the credit check. If this happens, it’s worth having conversation about your options if your heart is set on paying monthly.

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