After you believe you’ve removed the barring, test it by making a call that was previously blocked (e.g., an international call or a standard mobile call). If the call connects, the barring has been successfully lifted.
This is the weak link. Many users turn to O2 customer support (Guru chat or phone) only to be met with confusion. o2 remove call barring
This is the most user-friendly method and does not require remembering codes. After you believe you’ve removed the barring, test