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 SIM PIN.
Tap Change PIN.
Key in your current PIN and tap Done.
Key in a new four-digit PIN and tap Done.
Key in the new PIN again and tap Done.
If you key in an incorrect PIN three times in a row, your PIN will be blocked. To unblock your PIN, you need to key in the PUK which you can retrieve by contacting customer services. 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.