How do i convince my parents?

ok so ive been asking for a cell phone for more than 5 years..... and my parents say that i cant get one till im 13 and rite now im about 12 and a half, and i think that id have more friends if i had a phone cuz people always are asking me if i have one and since i dont they end up just walking away kinda, but anyways my friend abby just told me she got a phone and was asking me if we could text .... so how do i convince my parents into getting me a phone over the summer?