There is little question that this was an overreaction. But, the teacher was not to blame. He/she did the right thing, and contacted the administrator. As I understood it, the student was not just using her phone, but was talking on it, disrupting the class. She should have been disciplined.
A well reasoned argument is like a diamond: impervious to corruption and crystal clear - and infinitely rarer.
Here, as elsewhere, people are outraged at what feels like a rigged game -- an economy that won't respond, a democracy that won't listen, and a financial sector that holds all the cards. - Robert Reich