Cell Phone Rules Tightening at Schools

I have a 6year old starting school for the first time and I feel much more comfortable with him carrying a cell phone. If there is an emergency or he needs to get a hold of me, he can, with a touch of few buttons. People think I'm crazy for getting him a phone, but until you have a child of your own, you shouldn't judge. He is the most precious person in my life, and I would do anything for him. We live in california, where earthquakes happen often, and I am the type of mother who would go and pick up my child from school, if I was able to reach him on the phone and confirm that he is okay, I could leave him there until school let out.