How can I convince my parents to sign for me to get a phone?

I would convince them by trying several approaches... 1) Good grades and attendance at school. 2) Helping out with chores around the house other then ones already asked of you 3) Get a part-time job. Showing some form of responsibility, may help convince them.

i would tell them the pros of a phone for example if you are lost or you need to stay after school late and they wont let you use their phone( that's not likely to happen but you could try)