If your SIM card has been blocked, you can get it unblocked by inputting your SIM’s PUK code.
To find your PUK code, you’ll have to contact your network, either by phone or through the network’s website. Find Customer Helpline numbers for all UK networks here.
If you’re requesting a PUK by phone you’ll have to answer some security questions to confirm your identity.
These will either be questions you set up when you created your account, such as “what was the name of your first pet?”, or details on your payment and personal information.
Once your identity is confirmed, the network will provide a PUK code to unblock your SIM.
Some networks make the process easier by providing PUK codes online. Go to your network’s website, log into your customer account and navigate to the page for unblocking your SIM – you can grab the code there.