The Geeks' Den

When the iPhone screen is locked, the only option you see on screen at the time of incoming call is ‘Slide to answer’.

So how do you reject if you don’t want to answer the call?

1. You can let it ring and Mute the ringer by clicking the power button at the top of the phone ONCE. Alternatively you can press the volume bar at the sides to mute the ringer as well.
2. If you don’t want to accept the call at all and want it go to your voice mail instead, press the power button at the top of the phone TWICE. That will reject the incoming call immediately and send the caller to your voice mail.

NB: If your iPhone screen is not locked, you are presented with an option to Answer or Reject the call.