Even Cellular Phones which are not activated on a cell plan can be used to make 911 calls -- as long as the battery is charged. Many groups distribute old/"no longer used" cell phones to persons needing them strictly for emergency use without being out the expense of a monthly charge.
Also note that a special Emergency Number worldwide for cellular phones is 112. If one finds themselves in an emergency out of their coverage area, dialing 112 will cause the mobile to search any existing network to establish the emergency number for you. Interestingly, 112 can be dialed even if the keypad is locked.
Keys Locked in Car?
As long as you have a car with remote keyless entry and you have a spare keyless remote at home, this tidbit of info could come in handy and perhaps save a locksmith fee if you lock your keys in the car. Assuming you have your cell phone handy (or if yours is locked in the car along with the keys and you can find someone who will lend you theirs), call that person that has you spare keyless remote. Hold the cell phone about a foot from the door and have the person with the spare remote press the unlock button while holding it near the phone on their end. The car will unlock. How about that?
Hidden Battery Power!
In the event that your cell battery is very low and a call is necessary, there is some reserve power stored in your phone. It can be activated by pressing the keys *3370# The cellular will restart with this reserve and will reflect a 50% increase in battery. This reserve power will then get recharged the next time your cell phone is charged.
How to determine your cell phone's serial number?
Press the following keys on your cell phone * # 0 6 # A 15 digit code will appear on the screen. this number is unique to that particular cell phone. Record that number somewhere. If the phone is ever stolen, call the cellular service provider and give them the code as a stolen phone. They can then block your stolen phone such that even if the thief changes the SIM card the phone is totally useless. You probably won't get your phone back, but it's of no value to the thief! If everyone would do this when their cell phone is stolen, there would be no point in stealing cellular phones.
FREE Information Calls
Cellular service providers typically charge a fee ($1.00-1.75 or even more) for 411 information calls. Since we typically don't have a phone directory in our car, it's not uncommon to need the use of this service. If you need to use the 411 information service, simply call (800) FREE 411 [or (800-373-3411] and no charge will be incurred. Neat!