A SIM PIN code is an additional security measure that you can activate to keep your data safe.
The PIN is a 4-digit number that is saved directly to your SIM card, so it follows the SIM even if you switch it into a new phone or another device.
You can lock a phone with a passcode, but if you don’t have a SIM PIN you can’t protect your SIM if it is stolen.
If the SIM PIN is entered incorrectly 3 times, your SIM is blocked and cannot be used until a PUK (Personal Unblocking Key) is input, which you can get by contacting your network.
If a PUK is entered incorrectly 10 times then any data, contacts, files or photos on the SIM will be permanently erased.
To set a SIM PIN, go to the Security settings on your phone and set up a SIM card lock. You’ll need the default PIN, which you can get from your network or find in your SIM’s packaging or documentation (if you kept onto it). You can then set a 4-digit code to lock your SIM with.