Receiving a call on your iPhone is just about like answering any other phone you're familiar with. When your iPhone rings, you have the choice of accepting the call or rejecting the call.
Accept the call
To accept a call, you have three options:
Tap Answer and greet the caller in whatever language makes sense.
If the phone is locked, drag the slider to the right.
If you are donning the stereo earbuds that come with the iPhone, click the microphone button.
If you are listening to music on your iPhone’s iPod when a call comes in, the song stops playing and you have to decide whether to take the call. If you do, the music will resume from where you left off after the conversation ends.
Reject the call
Here are three ways to reject a call on the spot and send the call to voicemail:
Tap Decline. Couldn’t be easier than that.
Press the Sleep/Wake button twice in rapid succession. (The button is on the top of the device.)
Using the supplied headset, press and hold the microphone button for a couple of seconds and then let go. Two beeps let you know that the call was indeed rejected.
Sometimes you’re perfectly willing to take a call but you need to silence the ringer or turn off the vibration. To do so, press the Sleep/Wake button a single time, or press one of the volume buttons. You’ll still have the opportunity to answer.