How do you qualify for a Sprint upgrade?

To qualify for an upgrade to a new phone with Sprint, you must have an account in good standing for at least one year. An account in good standing is one for which service has not been interrupted due to failure to make timely payments.

Upgrade by renewing a contract; new contracts typically offer new phones as part of an agreement to commit to service for a designated time period. You can also upgrade prior to the end of an existing contract by agreeing to the terms of a lease for a new phone, but only if you meet the aforementioned conditions.