How does a pay as you go SIM work?
A pay as you go SIM is topped up in advance, allowing you to choose exactly how much you want to spend on calls, texts, and data. You are not tied to the provider you purchase the pay as you go SIM from, and can terminate the service whenever you wish. Pay as you go SIMs for mobile phones are the most common, but there are also pay as you go SIMs that are particularly suitable for devices like alarms and trail cameras. With some providers, you can also choose between pay as you go SIM and contract when purchasing mobile broadband.
You can order a pay as you go SIM directly from the provider’s website, but some providers also offer their pay as you go SIMs in physical stores or through retailers such as petrol stations and supermarkets. If you purchase the pay as you go SIM in a physical store, you may need to pay a small amount for the actual SIM card. Additionally, you may need to top up the pay as you go SIM with one of the provider’s price plans to be able to use it. If you purchase the pay as you go SIM online, the SIM card itself is often free. You only pay the amount required to top up the pay as you go SIM.
Info! To be able to make calls, send texts, and use data, you need to top up the pay as you go SIM with a price plan. Most price plans work by paying a fixed amount each month for unlimited minutes and texts and a set amount of data. There may also be price plans with variable rates, which means a certain amount is deducted per minute, text(s), and MB/GB data from the balance you have loaded onto the card.
When you have ordered a pay as you go SIM, you will receive a SIM card for your device to use. The SIM card contains all the necessary information about you and your pay as you go SIM, and is the actual link between you and your provider.
How to choose the best pay as you go SIM
Choose a provider with good network coverage where you live
A prerequisite for using your pay as you go SIM as you wish is that the provider has good network coverage in the area where you live or will use the pay as you go SIM the most. On many providers’ websites, you can enter your postcode to check their network coverage in your area.
Decide if you want a wide range of pay as you go SIMs
The range of different pay as you go SIM solutions and pricing plans varies between different providers, so it’s important to start by considering what type of pay as you go SIM you are looking for and the type of features you need. If the minutes and data you use each month varies greatly, it’s good to have several different top-up options to choose from.
Some providers also offer SIMs with improved minute and text rates from the UK to abroad, so this can also be a factor to consider when comparing offers.
Decide if you want to be able to use the pay as you go SIM abroad
After Brexit, British providers are no longer obliged to offer free roaming in EU countries, but several still do. With some providers, however, you must pay extra to use the pay as you go SIM abroad, whilst some do not allow you to use a pay as you go SIM abroad at all.
If you travel frequently and want to use the pay as you go SIM during your trip, it is important to check the provider’s international terms for pay as you go SIMs before ordering.
Compare prices for minutes and texts
Today, there are many pay as you go SIMs that offer unlimited minutes and texts, but many providers also offer variable rates for pay as you go SIMs where you pay per minute and per text. This naturally depends on how much you plan to use your pay as you go SIM, but make sure you get a pay as you go SIM that offers the best value for money.
Prices are generally lower with smaller providers, but that doesn’t necessarily mean their pay as you go SIM is the best option for you. You should ensure that the provider also meets your requirements for customer service or international usage, for example.
Which pay as you go SIM is the cheapest?
Now Mobile 1 GB is the cheapest pay as you go SIM right now (checked on 07/10/2025). Top up from £2.5.
How to top up your pay as you go SIM
There are various ways to top up your pay as you go SIM. The easiest way to top up your pay as you go SIM is via the provider’s website or app. Many providers also offer the option to top up the pay as you go SIM by calling or texting, or via a voucher.
In our guide Top up pay as you go SIM, you can read more about how the different methods work.
How do I check my pay as you go balance?
You can usually check the balance on your pay as you go SIM by logging into your account on the provider’s website, or via the app if the provider has one. Otherwise, most providers also have specific numbers you can call to check your balance and any time limits on your price plan.
Do pay as you go SIMs expire?
Yes, pay as you go SIMs stop working if you do not use them at all after a certain period of time. Exactly how long you can keep a pay as you go SIM without using it varies between different providers, so check what applies with your specific provider. You can usually keep the pay as you go SIM for quite a long time without using it, often at least six months.
The validity period also varies depending on the type of pay as you go SIM you acquire. Pay as you go SIMs that include a certain amount of data, unlimited minutes and texts for a fixed cost generally only apply for 30 days. A pay as you go SIM that you top up with a set amount and then pay for each minute, text, and megabyte of data can usually be used until the money on the card runs out. However, some providers require you to use or top up that type of pay as you go SIM after a certain period of time for the pay as you go SIM to remain active. For example, you may need to use or top up the pay as you go SIM once a month, every six months, or every twelve months.
How to activate your pay as you go SIM
- Ensure your phone’s battery is fully charged.
- Turn off the phone.
- Remove your old SIM card and insert the new one.
- Turn on the phone.
- With some providers, simply inserting the SIM card into the phone is enough to activate the pay as you go SIM. You may receive a text informing you that the provider has started the activation. It may take a few hours for the process to complete.
- You may need to top up the pay as you go SIM for it to be activated. If you’re unsure how it works with your specific provider, you can contact them or visit their website.
- You may receive a confirmation via text(s) when the activation process is complete.
Can you switch from pay as you go SIM to SIM only?
Yes, if your provider offers both pay as you go SIM and SIM only, switching from one to the other should not be a problem. However, the method and terms may vary slightly between different providers. Generally, you can switch your plan yourself via the provider’s website or app, but in some cases, you may need to contact customer service to make the change.
In most cases, you will receive a new SIM card when you switch. In some cases, you will also receive a new number, but you can often switch back to your old number once you have received your new SIM card.
If you have money left on your pay as you go SIM when switching to a contract, some providers transfer this as a balance on the contract, but with others, the money on the pay as you go SIM is lost during the switch. For safety’s sake, you can check the process and terms with your chosen provider.
Can you use a pay as you go SIM abroad?
Yes, many pay as you go SIMs work abroad, and many also offer free roaming in countries within the EU. This means you can make calls, send texts and use data at the same rate as you would at home without any extra cost. However, there may be a limit to how much data you can use.
But with some providers, you have to pay extra if you want to use the pay as you go SIM abroad. Therefore, please check with your provider before you travel.
Frequently asked questions about pay as you go SIM
Yes, some providers offer pay as you go SIMs for mobile broadband. However, there are no pay as you go SIMs for fixed broadband.
No, there are no pay as you go SIMs that are valid indefinitely if they are not used. However, there are certain pay as you go SIMs that allow you to make calls, send texts, and in some cases even use data until the credit you have loaded onto the card runs out, regardless of how long it takes.
No, pay as you go SIMs are not being phased out. However, many providers have chosen to remove their pay as you go SIMs and focus more on their SIM only plans instead. But there are still many providers that offer pay as you go SIMs.
Yes, you can put a pay as you go SIM in a SIM free phone. As long as the phone isn’t locked to a specific provider, you can buy a pay as you go SIM from any provider and put it in your phone.
You can buy a pay as you go SIM online, but some providers also offer pay as you go SIMs in their physical stores or through retailers such as supermarkets and petrol stations.
Yes, in most cases you can top up extra data on your pay as you go SIM.
You can often check your pay as you go balance by logging into your account on the provider’s website, or app if they have one. In many cases, you can also call a specific number from the provider to find out your current balance.
A pay as you go SIM can cost from a few pounds up to around 30 pounds depending on the provider, the type of pay as you go SIM, and the tariff you choose. The SIM card itself is always free when you order online, but you will need to pay to make calls, send texts, and use data.
