you are lucky to be in this page and very smart to remember of securing your bank account , since your sim card now adays is your bank;
There is this one mistake that people of nowadays do (especially the illiterates), and that's the mistake of securing their phone; without the need of securing their bank account(sim)firstly; You may be wondering how your sim card transfigured to become your bank account;
It's just obvious that your sim card is your bank;
(INSTANCE:Because you use your sim card to do transaction sometimes and that's the most easiest place people go for transaction;
So for that reason , you need to secure your sim to avoid falling a victim to bank fraud; and the only way to do this is by securing your sim by setting up a personal pin of yours and not the default pin of your service provider;
So to do this, you have to go to your phone's control panel(settings); then select security option and you will still see another option asking if you want to set sim pin; click it to answer the query, then you will be prompted to input your puk(personal unblocking key) for verification;
Then after that you set your own preferred pin, after that you are set at the game and none is to hijack your sim,
Since that's the method they use in gaining access to your mobile number.