How to convince parents to get cell phone?

[JesseFontenot]

live with my grandmother & she bought me a prepaid phone, there's nothing wrong with it but its pretty much just for emergencies. i do free chores around my house. my grandmother is really old fashion so she doesn't think i need one. all my friends have real phones & its embarrassing to have a prepaid phone. i do ungodly amounts of work for her!!! she tells me money is tight & the next day she comes home with a new 3D tv & a new car. i offered to buy the phone myself. im responsible. i get up every morning take care of my dog & go to school while she stays in & sleeps. i come home with good grades from school. i dont have behavior problems, the only thing i do is an occasional dirty room. please help me idk wha else to do?????
btw im a couple months from 16 years old