you missed another one.
If his parents are paying for the phone. Cell phone bill has nothing to do with his monthly expenses and lets assume he uses his iPhone as an iPod as well. Again a great device for studying. I use mine all the time when I am studying to create back ground noise to block out other sounds while I am studying.
If his parents are paying for the phone, then maybe they can spot another $20 so their child doesn't starve to death.