How to pick up the phone on the iPhone so that it is busy?

Question

iPhone

I used to have a phone, I picked up the phone so as not to disturb and it was busy. How to pick up the phone on the iPhone, I tried to put it upside down, the call still goes on. I tried to lay down on the bed and on the sofa, the interlocutor can still get through and the call goes on. Maybe there is an application so that when it lies upside down, it determines and I was busy? Autumn needs this function, I feel I will soon return to the rotary phone (((

Answer 1

Do not disturb mode.
Customizable, including scheduling.

Answer 2

Power button.
By pressing it once: the sound and vibration are turned off, but the call continues. And by clicking on it a second time, you get the desired result.