The administration in my school would hand me my head if I gave an academic penalty for a behavioral issue.
Grades correspond to the information you've learned, and your ability to show how much you've learned. They're based on test grades, quiz grades, homework performance, projects, and other academic criteria.
Having your cell phone out in class is a discipline issue. Discipline issues carry penalties along the lines of detention or phone calls home or a referral or whatever.
When my son was in 7th grade, I got a phone call from his Home and Careers teacher. (Nope, not an elective. They had to take it.) He was in danger of failing the class because he (and apparently a number of the boys in the class) were not being attentive to her lessons on how to sew a pillow in the shape of a shark. His pillow was no better or worse than anyone else's, but his behavior had him in danger of failing.
I called the guidance counselor in no time flat. I went to Power School and pointed out his grades on all the projects listed there. The shark pillow wasn't yet due, so he couldn't possibly have failed Shark Pillows. How, then, could he possibly be in danger of failing??? I said that if his behavior was a problem, she could give him detention every day until he graduated from college and I would support her, but exactly what academic criteria was she using to give my son a failing grade??
She said she would speak to the teacher. I got a phone call about an hour later with some pretty serious backpeddling on the part of the teacher. And he passed Home and Careers. And will never ever again make a Shark Pillow-- I guess that's for preteen boys who anticipate a career in the upholstery field?