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.
Tap Mobile Data.
Tap SIM PIN.
Tap Change PIN.
Key in your current PIN and tap Done. The default PIN is 0000.
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.