I think mobile phone is your personal property. But sometimes it gets in the hands of your friends or family members. If you don’t want your phone to be used by yore family members or friends, then lock your SIM card and would be useful so it can’t be used by friends or family members who doesn’t know the lock code. Here i am gonna show you how to set up the sim card lock on your Android Phone. Go to menu ->settings > Location and security > Set up SIM card lock. You can toggle the setting on and off by simply checking the box.