I guess it depends on the parent, and why they feel the need to get one for their child. It should not be because the child keeps asking. How much is it going to effect their other social skills? Is it going to interfere with their school work?
My oldest son, now 26, was 16 when he got his first cell phone. My youngest son was 12, now 15. Hind-sight now............I wish I had waited until he was 14.
I have a great-niece, only 8...............her parents just got her a cell phone. I think this is definitely too young.