If you are locked out of your phone, it may ask you to enter the PUK1 code in order to unlock it.
The PIN and PUK codes can be found on the SIM card packet that is provided to you when the sim was purchased. There is a PUK 1 and PUK 2 code to help with securing your SIM pin. You can use it to unlock a blocked SIM pin.
How to access SIM PIN & PUK:
Step 1. Turn to the back of your sim card holder.
Step 2. Using a coin, gently scratch out the grey section as shown below to see your PIN & PUK.