You don't necessarily need to take it away, there are other avenues of punishment. Detention, Saturday school, no extra-curricular participation, suspension, etc. I was in high school right as dumb cell phones started to become a thing and those were our punishments if we were caught with phones out. We were allowed to have them, but they had to be either off or on silent, and in our bags (same as CD/MP3 players.) We were allowed to have them out to check them only during lunch and before and after school, or if we had to make a call, in the main office. I completely agree that kids shouldn't be using phones AT ALL during class time, but there's ways to allow them to exist and punish inappropriate usage that doesn't require teachers taking them. Teachers shouldn't be taking phones, that's a liability risk and not worth the effort.