I don't know how old you are. The teachers of my time would have manhandled you and took a paddle to your ass. The Pussification of America started when went away with corporal punishment.
Mom said it has gotten worse and she is retired but she was the Sgt Irmery type from Full Metal Jacket, hence why they begged her not to retire. A phone call will not disrupt the class, if that person talked louder she would just simply went to the student and just snatched it from her in mid call. If the student even attempt an assault, hey will be kicked out of school.......permanently. If the parents can't control their kids, my mom will educate them on parenting and kids being respectful. Hell, I am still scared of my mom, she can make me feel one inch tall just by her mouth alone and F-bombs is nothing.
I'm Dimaggio's hit streak. How did the teacher handle it wrong? Didn't he/she (sorry I didn't even notice the gender) the student refused and the teacher called for security, what else are they supposed to do. I"ll promise you the only reasons your mom could get away with that sort of thing is that she did it forever and the administrators are probably just as scared to eff with her as the kids are, AND she was also dealing with kids NOBODY ELSE WANTED, so if the administration punished her in any way she walks and they have to look for somebody else to send into the demilitarized zone (except for the likelihood of military stuff).
When I taught in the public schools of OK the principals still held power over the kids but the teachers had one thing to use, bluff and you knew not to push it too far because if the kids ever figured out how little power you really had then you really were up ****e creek. Teachers have to have the authority to run their classrooms, but to be honest so many good teachers have left the profession because of the crap we're talking about the ones who have come in their place are hit and miss, some are really good and dedicated, others love the position and the paycheck and couldn't teach a dog how to bark. When my kids were in school since I had taught there I knew which teachers were good and just trying to teach (and I supported them) and which ones were worthless (and they knew not to eff with me). I've defended my kids against punishments when I knew the teachers were wrong and I have supported them being punished when I knew the teachers were right. Had I not taught there previously and known all of them it would have been a lot more difficult.