This article seems to imply that there are two groups of people who call you: people who call you where you WOULD fish the phone out the pocket to answer, and people who call you where you wouldn't do so.

Personally, I don't care who is calling me. If my cell phone rings when I am engaged in a conversation with someone else, I don't answer it. I don't even fish it out of my pocket to see who's calling, because it doesn't matter who is calling, really.

What is more pertinent to me over who is calling, may be what the context of the call is. But how do you know the context of the call is. If your wife is phoning you, is she phoning you to see if you're still picking up fish for dinner? Or is she calling you because your daughter hit her head at soccer practice and she's at the hospital? The solution to the problem of context may be to have intelligent voice menus that people hear before they reach you. For instance, I may have a voice menu when people call me that say, "Press 1 if this call is of normal importance. Press 2 if this is a personal emergency." -- with different vibrating tones for each option. If they dial 1, you get a distinctive vibrate that goes to voice mail if you don't answer. If they dial 2, you get a distinctive vibration that indicates it's an urgent call that maybe requires that you break your attention from what you're doing.