Acer ICONIA SMART (S300) - Manual (Page 27)

27 The voice call screen
The voice call screen
Once you have dialed your number the voice call screen appears, which displays
the number/contact you are talking to, the call duration and the dialpad tab.
Answering or declining a call
When you have an incoming call, the number will be shown
on the screen. To accept or decline the call, tap the
appropriate button.
If you are answering a call from a locked state, slide the bar
to answer the call. To reject a call from a locked state, press
the power button.
Ending a call
To end a call, press End Call from the voice call screen.