I'm younger than most the guys on this forum but I got my first phone at 14. I bought it myself and paid for it with the money I made from mowing lawns and selling sodas at school.

I would give the kid a phone when after school activities such as sports or clubs came into the picture. Or at about 12-14. That's the age where they start hanging out with their friends more and start leaving houses to hang out at places such as the mall/movies/etc. My niece recently got a cell phone and she has some pretty reasonable restrictions. Such as: no phone at the dinner table, no phone during homework, phone stays downstairs at night, phone turns off before going to bed, parents can take/look at the phone whenever they want, and when the parents call she has to pick up immediately or call back within 20 minutes with a good reason.

The cell phone is a tool and a privilege. Also, any future phones and phone repairs are financially on the niece.