We are ~18 months through a 2-yr contract (on an older phone) and are interested in upgrading to the 4 Pro phone for our now-teenage daughter. However, the wording on the upgrade program is a little vague: how close to the end of the contract does one need to be before qualifying for a free device upgrade? A mere 25% discount on a $200 phone is not exactly incenting us to upgrade to a more expensive plan with Gabb.