Most of the time people contact me by instant message or comments for social stuff, and emails for work stuff. It's rare that I get a call that wasn't pre-arranged.

Actually I'd feel rude phoning someone without arranging it first. Not terribly rude, but a little uncomfortable. What if they are driving or in an important meeting?

So maybe phones are there to let me check messages and alerts when convenient. A huge proportion of the money you paid for that phone went on the data modem after all. It isn't really a phone means voice, or sound. But folders on a computer are not made of paper. It's just a word.

Not that I'd suggest putting your phone in a bag.