Are you being asked for the SIM PUK or a SIM Network PUK? If it is the SIM PUK then you will need to create a ticket with Public Mobile to get the PUK https://expert-messaging.publicmobile.ca/guest/chat/ Alternatively you could also just get another SIM card or ESIM.
If you have a fairly old phone and you are being asked for a SIM Network PUK it could mean that your phone is locked to a specific carrier. If that is the case you would need to call the carrier that your phone is locked with and let them know that you would like to get it unlocked.
