Audio
The iPhone’s headphones are similar to those of most current smartphones, incorporating a microphone. A multipurpose button in the microphone can be used to play or pause music, skip tracks, and answer or end phone calls without touching the iPhone. The 3.5 mm TRS connector for the headphones is located on the top left corner. The headphone socket on the original iPhone is recessed into the casing and is narrow when compared to some headphone jacks, making it incompatible with most headphones without the use of an adapter. The iPhone 3G has a flush mounted headphone socket.
Wireless earpieces that use Bluetooth technology to communicate with the iPhone are sold separately. It does not support stereo audio.
The loudspeaker is used both for handsfree operations and media playback, but does not support voice recording..
Composite or component video at up to 576i and stereo audio can be output from the dock connector using an adapter sold by Apple.
Battery
The iPhone features a built-in rechargeable battery that is not user-replaceable, similar to existing iPods, but dissimilar to most existing cellular phones. If the battery prematurely reaches the end of its life time, the phone can be returned to Apple and replaced for free while still in warranty, one year at purchase and extended to two years with AppleCare. The cost of having Apple provide a new battery and replace it when the iPhone is out of warranty is, in the United States, US$79 and US$6.95 for shipping.
Since July 2007 third party battery packs have been available at a much lower price than Apple's own battery replacement program. These kits often include a small screwdriver and an instruction leaflet, but as with many newer iPod models the battery in the original iPhone has been soldered in. Therefore a soldering iron is required to install the new battery. This is not the case with the iPhone 3G as it uses a different battery fitted with a connector.
The original iPhone’s battery was stated to be capable of providing up to seven hours of video, six hours of web browsing, eight hours of talk time, 24 hours of music or up to 250 hours on standby. Apple's site 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 the iPod batteries.
The iPhone 3G’s battery is stated to be capable of providing up to seven hours of video, six hours of web browsing on Wi-Fi or five on 3G, ten hours of 2G talk time, or five on 3G, 24 hours of music, or 300 hours of standby.
The Foundation for Taxpayer and Consumer Rights, a consumer advocate group, has sent a complaint to Apple and AT&T over the fee that consumers have to pay to have the battery replaced. Though the battery replacement service and its pricing was not made known to buyers until the day the product was launched, a similar service had been well established for the iPods by Apple and various third party service providers. source
