Recently my dad entered his SIM PIN incorrectly three times and it locked him out. Turns out his mobile operator has an IVR service which hands out the PUK to a

Recently my dad entered his SIM PIN incorrectly three times and it locked him out. Turns out his mobile operator has an IVR service which hands out the PUK to any phone number you enter! No authentication whatsoever, just the phone number. How common is this?