Here’s a link to a quick rundown of the external physical buttons/connectors on the iPhone. The top right button wakes/sleeps the phone, but also immediately silences the iPhone when receiving a call with a single tap, or forwards to voice mail with a double tap.
The top left audio jack works with the included stereo earphones/microphone, but will require an adapter to accommodate third party earphones because it’s too deep for them to connect properly.
The home button on the front of the iPhone also provides a way to force quit stalled applications by holding it down for six seconds.
http://www.nytimes.com/ref/business/20070627_POGUE_GRAPHIC.html
