Here’s what you need to know about using a prepaid (PAYG) SIM card on your device in the UK.
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What’s a prepaid SIM card?
Is there a difference if my phone is unlocked vs. locked?
What SIM size should I use?
What's a prepaid SIM card?
A prepaid (PAYG) SIM card lets you pay for a network’s service upfront. A postpaid SIM is tied to a monthly plan billed to you based on your allowance or usage.
In short, your usage depends on the credit or bundle you’ve added. Most UK networks and MVNOs (e.g., EE, O2, Vodafone UK, Three, giffgaff, Lebara, Lycamobile, SMARTY, VOXI) offer prepaid options.
Is there a difference if my phone is unlocked vs. locked?
Prepaid SIM cards can be used in unlocked phones, since they’re not tied to a specific network. Just purchase a prepaid SIM (or eSIM, if supported) from the UK network of your choice and insert it into your refurbished phone.
Phones that are locked to a single network won’t work with other networks’ prepaid SIMs. If in doubt, check your phone’s unlock status with your current network or see our UK guide on connecting your phone to your network.
What SIM size should I use?
SIM cards come in different sizes: standard, micro, and nano. The nano SIM is now the most widely used in modern phones.
The size you need depends on your phone’s model and year. Many UK prepaid SIM packs are “multi‑SIMs” that can be snapped down to micro or nano size to fit your device.
eSIM: Increasingly, UK networks support eSIM on compatible phones. If your device supports eSIM, you can activate a prepaid plan by scanning a QR code instead of inserting a physical SIM.
When in doubt, check with the UK network you plan to buy from to make sure the SIM (or eSIM) is compatible with your specific model and that your device is unlocked.