Electronic gadgets in class

As I move into the curmudgeon stage of my life, I find that I can articulate what annoys me more (maybe because more things do?). One thing that really annoys me is when students use their phones in class. There are three main ways I see students interact with their phones in class, ranked here from most annoying to least:

1. Forget to turn their ringers off
A cardinal sin! This annoys everyone in the class. Worse when using an obnoxious ringtone. Even worse when during an exam (when cellphones are forbidden, and stored in the back/off to the side so the ringtone can't be turned off).

2. Constantly check their phone
I find this really distracting when I am teaching. The motion draws my eyes, and then I find myself wondering what is so important. It also annoys me that the student is obviously not paying any attention to the lecture. Why bother coming, then? It is just like coming to the lecture and then reading the newspaper, and just as obvious. Students forget that from the front of the room, I get a pretty good view of every seat, so it is pretty noticeable when someone keeps checking their phone. It is hugely distracting to neighbors as well, whose eyes are also drawn by the motion and the screen. 

3. Students texting/Facebooking/whatever on their phone
Somewhat less distracting than #2 because their is less to draw attention, but seriously why come to class if you aren't going to pay attention. I know lots of people think they can multitask,and both text and pay attention to the lecture, but loads of studies have demonstrated that this is BS, and the constant attention swapping makes effective learning impossible. Students may think that their professors don't care about teaching, but I do, and I put a lot of effort in. Texting in class feels like a slap in the face, and I find it extremely rude and distracting.

4. Students keeping their phones in their laps for the whole class
This is at least an attempt at subtlety. Students doing this may not realize this, but from the front of the room, this looks like the person is staring at their crotch for the whole class, which looks very bizarre.

Strangely enough, students using laptops in class is a lot less annoying (to me anyway--I suspect someone browsing in class is probably pretty distracting to their neighbors!). I have seen many students who take notes on their laptops, so there is at least the plausibility that the student is working and paying attention. I distribute my notes electronically, and so it isn't that odd that someone might prefer to use them that way as well. That said, I am well aware that some of the laptop using students are probably doing something else. If they are, it is less disruptive than a phone. There is less motion involved, and I can't see the glow of the screen, so it is less attention grabbing.

I was talking about this issue with a colleague, who is considering banning cellphones entirely in class. Have any of you tried it or thought about it?