Lots More Information Lots More Information Prev Next Related HowStuffWorks Articles How Telephones WorkHow Wiretapping WorksHow Batteries WorkHow Emergency Power Systems WorkHow Power Distribution Grids Work More Great Links Theater of ElectricityElectricityForum.comU.S. DOE: Electricity Up Next How MagicJack Works What should I do if the home button on my iPhone stops working? How do I take a screen capture on my smartphone? What's the best e-reader app to use on a smartphone? Why are 'unlocked' phones more expensive than locked ones?