It IS on accident most of the time. I could be working on homework 或者 stuff for college.That kind of stuff comes first in my book. Except when there is an emergency. That's when people know to just call my house phone and they get a response 99% of the time.
Depends. Sometimes I ignore texts, emails...etc if the person was a 婊子, 子 to me 或者 hurt me in some way. I'll also ignore if I'm in class 或者 really depressed 或者 anxious to talk to anyone at the moment.
However in situations where I receive an 电子邮箱 about a message I have received on Facebook, then I tend to ignore it for a while, get work done, then go check it out later in the day.
I do however ignore almost every phone call on my cell that isn't from my direct family. I don't do talking on the phone unless it is important.