Ensure you lock your sim card with a pin once that is done no one can have access to transact with your sim when your phone is stolen…
Go to settings on your phone, then to security you will see sim setting/ sim lock if it is mtn the default code is 00000 then you will see change pin, you then change to your 6 desired pin numbers .. u can always remember..
Airtel default sim lock is 1111
GLO is 0000.
