Using the Controls on the Bottom of Your iPhone
You’ll find several important controls along the bottom of your iPhone. These iPhone controls include the speaker, the dock connector, and the microphone.
Speaker: The speaker is used by the iPhone’s built-in speakerphone and plays audio — music or video soundtracks — if no headset is plugged in. It also plays the ringtone you hear when you receive a call.
Dock connector: The dock connector has two purposes:
You can use it to recharge your iPhone’s battery. Simply connect one end of the included dock connector–to–USB cable to the dock connector and the other end to the USB power adapter.
You can use it to recharge your iPhone’s battery as well as synchronize. Connect one end of the same cable to the dock connector and the other end to a USB port on your Mac or PC.
Microphone: The microphone lets callers hear your voice when you’re not using a headset.