Get the phone... You want him to learn how to use it and you want to ensure that you can find him (and the phone) if you need to.
DC traveled over an hour to school for a time and had a flip phone and ipod. I would call and they would NEVER answer since they were on the ipod with headphones. Transportation would be an hour late (due to traffic or whatever), I was panicking, and DC was fine, just busy with their phone. Finally (after two straight weeks of them getting home seriously late), I switched them to an Iphone. They fought me on it. However, it had everything in one place (movies, music, books, phone calls, text, Google Maps...Find My Phone). Also, it helped DC figure out the technology (they are NOT tech savvy and don't want to be). Having everything in one place was the key.
The easiest thing is to just get the phone. Check school policy, it's different everywhere, but generally they can't use them at school. Make sure your DC knows the policies at school, activities, ect. My DC rarely pulls it out at school unless the teacher instructs them to or there is a severe emergency (that has happened once). However they have a few friends who "check their phones" when they get to school. Make sure your child knows the rules, and get the phone. It's just a matter of time.