Tap Accept to answer an incoming call. Or if iPhone is locked, drag the slider. You can also press the center button on your headset.
Silence a call. Press the Sleep/Wake button or either volume button. You can still answer the call after silencing it, until it goes to voicemail.
Decline a call and send it directly to voicemail. Do one of the following:
Press the Sleep/Wake button twice quickly.
Press and hold the center button on your headset for about two seconds. Two low beeps confirm that the call was declined.
Tap Decline (if iPhone is awake when the call comes in).
Note: In some areas, declined calls are disconnected without being sent to voicemail.
Respond with a text message instead of answering. Tap Message and choose a reply or tap Custom. To create your own default replies, go to Settings > Phone > Respond with Text, then tap any of the default messages and replace it with your own text.
Remind yourself to return the call. Tap Remind Me and indicate when you want to be reminded.