Credit debt at young age??

im only 16 and ive been getting letters from a credit card company saying that i owe cingular money but i never knew about any of this. i didnt even know i had a cell phone under my name. it says i owe like 600 something. i asked my mom if it will show up on my credit report when i turn 18 and she says no because shes the only one that has my ssn besides me and no it wasnt her. they cant charge me right? because im under 18 and i never even gave anyone the authorization for my name to be used and if they can how do i clear that up? thanx for any help :D