Cell Phone Etiquette

So, let's briefly discuss cell phone manners here.

When is it appropriate to answer texts?
--For me, when I am in a small group, I tend to only respond when it's a time-sensitive matter. Stupid texts can wait. Large groups..it doesn't matter as much.

How about casual Facebook-ing or Internet browsing?
--For me, it is never appropriate in small groups, especially if there are 3 or less people. I think it is incredibly rude. I also feel the same about large groups too, because you should probably be there in the moment.

Phone calls?
--If it is an unknown number, I will probably skip it, unless I am expecting a phone call from a service place or something. If it is someone I know, I will excuse myself from the group (large or small), to take the call and talk away from people.

Anyways, I find it soooo frustrating that so many people engage in these behaviors, and basically non-verbally tell the people they are with that they are unimportant. It is bothersome that these habits have become so commonplace that some people don't even bat an eye. Me? I sit there, fuming with my arms crossed, thinking about passive-aggressive ways to let these people know how much it bugs me.. and then, in my true fashion, never do anything about it.