If I remember correctly, VZW doesn't have this (unlimited text to any carrier) as a feature that can be added, but rather it's included in their plans (must be a "Select" plan or higher). Considering that you're 16 you are either on a family plan or prepaid. If the former, then the account holder will have to change to a "Select" plan or higher, and this is, of course, assuming that they want to do this, as it would add more to the bill.