In certain circumstances, perhaps. My niece has visitation with her biological Grandmother, who is a nut job. My sister sends her with a cell phone for safety reasons and she is only 4. BUT, I don’t think that young kids should have their own cell phone. Kids just aren’t equipped to make good decisions. A phone is a responsibility, and I think that kids need to prove that they can take care of one.
I had one when I was seventeen and it was my problem to pay the bill. I racked that up real quick, but paying it off was a lesson learned.