HTC One - Receiving Calls

Receiving calls
When you receive a phone call from a contact, the Incoming call screen
appears.
HTC One will automatically adjust the ringtone volume when you
use the polite ringer and pocket mode features.
Answering or rejecting a call
Do one of the following:
§ With HTC One facing up, lift the phone next to your ear to answer a
call.
§ If the display is on when you get a call, tap Answer or Decline.
§ If the display is locked when you get a call, drag or upwards.
§ Press the POWER button twice to reject a call.
Muting the ringing sound without rejecting the call
Do one of the following:
§ Press the VOLUME DOWN or VOLUME UP button.
§ Press the POWER button.
§ Place HTC One face down on a level surface.
If HTC One is already facing down, it will still ring when there are
subsequent incoming calls.
Phone calls 151