Think of it as an overflow! Your regular data gets consumed that the extra 1GB is there. Say you go over my 250 mb per month.... then that 1GB will be eaten up.... if you dont go over your regular allotment, it'll still be there...
Do you mean that you inserted a Public Mobile sim into your phone and it said it was locked? It sounds like your phone might be locked to the previous carrier and you'll have to contact them to unlock it...
