@Houndstooth, I personally view school as a more laid back kinda thing, compared to a job place (what with classes migrating to be online and stuff, plus, I think eventually teachers are going to become obsolete in a few decades time). Tbh, you are the customer at a school. You are buying knowledge. Once you are in the class, you have already paid the teacher their salary. However, some schools (if not all, I don't know fully) pay some sort of 'commission' based on how well their classes do (passing rates, etc), If they are gonna kick you out of the class for having a phone, they need to provide solid proof that its causing a disruption, such as lower grades, and other students physically not paying attention, or complaining about the phone-wielding student.
What I'm trying to say is, not allowing phones in class is an archaic, conservative-type rule, that really doesn't have any need in our time. Texting in class is just as distracting (if not, less than!) talking to a person next to you, and most classes I have been in allowed discussion between students during class.
You may argue that there is a difference between texting your friend about what you're gonna do after school, and talking to another student about relative classroom material, but that's not the point, the point here is distraction. Talking makes an audible noise, which to some students, can be distracting. Typing on a silenced phone is only distracting you if you are doing it at an inappropriate time in the classroom setting, such as during a lecture, but if the class is idle, as happens a lot of time, then I believe it shouldn't be completely out of line to want to say hey to your friends. Now, whether or not they respond, is based on whether or not they are in an appropriate time to respond, that is their issue, but if two classes are idle at the same time (trust me, it can happen!) I don't see why not.