Your PIN protects your SIM from unauthorised use if your mobile phone should get stolen. You can change your PIN to a PIN of your own choice making it easier to remember. Before you can change your PIN, you need to turn on use of PIN.
Slide your finger downwards starting from the top of the screen.
Tap All settings.
Tap Network & wireless.
Tap Mobile & SIM.
Tap SIM settings.
Tap Change SIM PIN.
Tap the field below "SIM PIN" and key in your current PIN.
Tap the field below "New SIM PIN" and key in a new 4-digit PIN.
Tap the field below "Confirm new SIM PIN" and key in the new PIN again.
If an incorrect PIN is entered three times in a row, your SIM will be blocked. To unblock your SIM, you'll need to key in your PUK. The PUK can be obtained by contacting Customer Service. Please note:
If an incorrect PUK is entered ten times in a row, your SIM is blocked permanently. In this case, you'll need a new SIM from Optus.