This guide is for Classic SIMs, if you've got a Smart SIM please contact the Customer Support team to request your PIN.
Your PIN code is 0000 or 1234 by default, although you probably won't need it. We recommend that you protect your phone with a passcode or biometric security feature. To be extra secure you can also set-up a new PIN for your SIM in your phone settings, if you do that and forget it the above PINs won't work and we'll be unable to retrieve the PIN for you.