Best SIM-only deals: save money on mobile deals

Looking for the best SIM-only deals? We've got you covered

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SIM-only deals are ideal for anyone who doesn’t need or want a new phone, and who would like flexibility rather than being tied to one particular provider for months or years at a time. If you don’t want to be locked into a lengthy mobile contract, and you’ve already got a phone, these best SIM-only deals could be just the ticket. 

In this guide, we explain everything you need to know about SIM-only deals, as well as providing a shortlist of some of the best deals currently available.

The best SIM-only deals

Asda Mobile SIM only | 3GB data | £5 per month | 1 month contract | Unlimited minutes and texts  (opens in new tab)

Asda Mobile SIM only | 3GB data | £5 per month | 1 month contract | Unlimited minutes and texts  (opens in new tab)

This Asda SIM-only deal is just £5 and you’re not tied into a contract, so you can leave when you want to. With Asda Mobile you can roam like you’re home in 37 European destinations and Asda Mobile is powered by Vodafone. 

Smarty SIM Only | 30GB data | £8 per month | 1 month contract | Unlimited minutes and texts  (opens in new tab)

Smarty SIM Only | 30GB data | £8 per month | 1 month contract | Unlimited minutes and texts  (opens in new tab)

This Smarty SIM-only deal is only £8 per month on a 1-month contract, so you can cancel at anytime. As part of the plan you also get EU roaming so you can use 12GB of your allowance around Europe at no extra cost. 

Vodafone SIM Only | 20GB | £8 per month | 12 month contract | Unlimited minutes and texts  (opens in new tab)

Vodafone SIM Only | 20GB | £8 per month | 12 month contract | Unlimited minutes and texts  (opens in new tab)

Vodafone’s SIM-only deal offers unlimited minutes and texts, with 20GB all for just £12 per month for 12 months. There is also no upfront cost.

Virgin Mobile SIM Only | 50GB data (5G) | £12 per month | 1 month contract | Unlimited minutes and texts   (opens in new tab)

Virgin Mobile SIM Only | 50GB data (5G) | £12 per month | 1 month contract | Unlimited minutes and texts   (opens in new tab)

This SIM-only deal is offering 50GB data, unlimited calls and texts for just £12 per month. You can roam like home in 43 destinations overseas, use 5G at no extra cost and Virgin Mobile has faster 4G on average than Vodafone, Sky and Three. As Virgin Media is powered by the O2 network, you also have access to their rewards app, O2 Priority. 

Smarty SIM Only | Unlimited data (5G) | £16 per month | 1 month contract | Unlimited minutes and texts  (opens in new tab)

Smarty SIM Only | Unlimited data (5G) | £16 per month | 1 month contract | Unlimited minutes and texts  (opens in new tab)

This Smarty SIM-only deal is £16 per month on a 1 month contract with unlimited data, texts and minutes, so you can cancel at anytime. As part of the plan you also get EU roaming so you can use 12GB of your allowance around Europe at no extra cost. 

What is a SIM-only deal?

As the name suggests, with a SIM-only deal, you only get a SIM card and no handset. SIM is an acronym for ‘Subscriber Identity Module’ and it’s basically the small bit of plastic that slots into the back of your phone. It’s the SIM that allows you to connect to your network so you can make calls and send text messages. 

SIMs also hold all the information you need on them, such as emails, contacts and so you, and are transferable, so you can move yours over to another handset at any point if you want to, provided it isn’t locked to another network. 

How does a SIM-only deal work?

There are two main types of SIM-only deals – pay monthly and pay as you go. With a pay monthly SIM-only deal, you’ll sign up for a rolling 30-day contract and will get an allowance for calls, texts and data to use each month. If you want to end the contract at any time, you simply give 30 days’ notice. Some SIM-only deals allow you to commit to a 12-month contract if you’re comfortable being tied in for a longer period.

Pay-as-you-go SIM-only deals require you to top up your phone with credit as and when you need it, so you’re not tied into a contract at all. Once you’ve found and applied for the SIM-only deal you want and you receive the SIM from the network provider you’ve chosen, you simply insert it into your telephone, following the instructions you will have been provided with, and you should be good to go.  

Why get a SIM-only deal?

The biggest advantage of a SIM-only deal is that they are much cheaper than other mobile deals because you’re not paying for a handset. The only cost is for the data, texts and minutes you’ll use. 

Another benefit is that SIM-only deals are more flexible than other types of mobile deals – you won’t be locked into a lengthy contract, so if you want to switch providers, you’ll usually only have to give 30 days’ notice. 

(MORE: How to save money on your mobile phone deal)

SIM-only need-to-knows

Here’s an at-a-glance guide to some of the essentials you need to know about SIM-only deals.

What does a SIM card do and what’s stored on one?

A SIM card is essentially a computer chip that is used to store information such as your contacts, emails, photos and messages. It enables you to connect to your network provider so you can make calls and send texts and so on. Without a SIM you wouldn’t be able to use your phone.

How much data do you need?

The amount of data you’ll need from your SIM-only deal depends on how you use your phone. For example, if you regularly download large files on your phone, you’ll need more data than someone who just uses their phone to send texts and make calls. Check previous bills to see how much data you tend to use each month, but as a general rule, most people typically use up to around 3GB a month.

What contract lengths are available?

SIM-only deals typically run on a 30-day rolling contract, providing you with flexibility if you decide you want to switch to a different network. However, it is usually possible to sign up for a 12-month contract if you want to. 

How to switch SIM-only deals

If you want to move to a different SIM-only deal, you’ll need to wait until your current contract finishes. Most contracts only run for 30 days so you shouldn’t have to wait long. If you want to keep the same number when you move, you’ll need to request what’s known as a PAC code (Porting Authorisation Code) from your existing provider which you can do by texting PAC to 65075. When you’ve got your PAC code, you’ll need to get in touch with the provider you’re joining and give them the code so they can then arrange the switch on your behalf.

Will my phone be locked to a network?

If you have a SIM-only deal, then it’s only the SIM that is locked to the network and not the phone handset itself. A locked phone is a handset that will only accept a SIM card from a particular network. From December 2021, mobile companies will be banned from selling phones which only work with their network.

How to unlock a smartphone

If you want to unlock a smartphone that’s locked to a particular network, you’ll need to contact the network provider and give them your IMEI number, which essentially identifies your phone. You can find this in the Settings section of either your iPhone or Android phone under the ‘About’ or ‘About device’ heading. Different networks have different approaches to unlocking phones, so you’ll need to check with them how long the process will take and whether there are any costs involved. 

SIM networks and piggybacking

Even though there are only four main networks (Vodafone, EE, Three and O2) several other providers piggyback on their signals, often offering competitive deals. This means that even if you can only get good coverage in your area from one particular provider, you should still be able to pick from a wide choice of deals when you include piggyback providers. These providers include Smarty (Three), GiffGaff and Tesco Mobile (O2), Plusnet and BT Mobile (EE) and Voxi (Vodafone).

Vaishali Varu
Staff Writer

Vaishali graduated in journalism from Leeds University. She has gained experience writing local stories around Leeds and Leicester, which includes writing for a university publication and Leicester Mercury. 

She has also done some marketing and copywriting for businesses.

When she is not writing about personal finance, Vaishali likes to travel and she's a foodie.

With contributions from