I know now everyone seems to have a smart phone or iPhone. But do you really understands the true function of it, if not please continue read it.
Most of us do not know the hidden function;
1) Dial 112 for emergency when there is no coverage or you do not know local emergency number. More special is you don't have to unlock your phone to dial.
2) Great way to prevent your phone from being stolen, key *#06# and you can see 15 numbers on screen. Write it down and keep in safe place. In case your phone is stolen, you can cancel your sim card and lock phone by calling service provider.
3) Some of us encounter car is locked with keys in it. Don't worry just call anyone that has your spare key at house. Then put ask him to put spare key near to his phone and your phone near to car and ask him to click open button. This is unlock your car without any cost, great.
# Out of battery, no problem. Just dial *3370#
Hope the tips are helpful.