The cell phone in your hand is for your convenience, not for the benefit of your callers.
We always pick it up promptly, interrupting ourselves in the hope that it would be some important call. I have seen people picking phones during family dinners, while engrossed in a book, while meditating and exercising and at those times when they did not want to be disturbed. Why do we do it?
We run to pick it up as if our lives depended on the call being answered at once. We do it because we simply want to know who is calling us. Often it is just another way to put off doing something you don’t really want to do.
But believe me, it is not worth getting distracted. The world is not going to fall apart because you did not pick up the call when it rang. Consider a cell phone to simplify your life, nothing more than that. When you are in a meeting, having a conversation, in meditation, while exercising, making notes, listening to a podcast, playing with your child, having a special moment with family and friends, you need not pick up the call and change the mood.
Do definitely call back all your callers at your convenience. You may find it difficult to cultivate this habit all of a sudden, but over the course of time, I have found lot of peace in this and there was hardly an emergency moment, wherein I felt, I should have picked up the call.
So, in case I don’t pick up your call, don’t fret, I will call you back at my convenience.