Seriously, people tend to underestimate how unsafe it is to give other people access to their phone or their personal details such as NIN. When your number/information is associated with crime, then it is your headache even though you might be innocent. It is fearful that there are still those people whom will casually provide their sim or NIN without even considering the repercussions. It is far safer to buy that person his or her own sim card or phone credit. Preservation of your identity and phone is actually preservation of oneself against the hassle that one did not initiate. This is something which everyone ought to take seriously.