IPhone not user-replaceable. The iPhone can be charged when connected to a computer for syncing across the included USB to dock connector cable, similar to charging an iPod. Alternatively, a USB to AC adapter (or "wall charger", also included) can be connected to the cable to charge directly from an AC outlet. Some models of the iPhone support wireless charging. Apple runs tests on preproduction units to determine battery life. Apple's website says that the battery life "is designed to retain up to 80% of its original capacity after 400 full charge and discharge cycles", which is comparable to iPod batteries.
IPhone 3GS There are two ways to activate Voice Control: hold the Home button while in the home screen for a few seconds; or, change the effect of what double-clicking the home button does so it will activate Voice Control (only on iOS 3.x; on iOS 4 or later, double clicking the Home button opens the multitasking bar). VoiceOver, Color Inversion, and Text Zoom were introduced as exclusive features to the iPhone 3GS. VoiceOver is a feature that dictates music details, system menus, text, and other things which was first introduced on the third generation iPod shuffle. Color inversion reverses the color