1. The emergency number worldwide for mobile is 112. if you find yourself out of the coverage area of your mobile network and there is an emergency, dial 112 and the mobile with search any existing network to establish the emergency number for you. interestingly this number can be dialed even if the keypad is locked. 2. Have you locked your keys in the car? does your car have remote keyless entry? if you lock your keys in the car and the spare key is at home, call someone at home on their cell phone from your cell phone . hold your cell phone abotu a foot from your car door and have the person at your home press the unlock button, holding it near the mobile phone on their end. your car will inlock. distance is no object . you could be hundreds of miles away and it will work. 3. Hidden battery power- imagine your cell battery is very low. to activate , press the keys *3370# and your cell will restart with this reserve and the phone will show 50 % increase in battery. this reserve will get charged when you charge your cell next time. 4. Free directory service for cells- when you need to use the 411 information option, simply dial (800) free 411 or (800) 373-3411 without incurring any charge at all. try this and see if it works .. it may not work on some phones ...