There is a cancellation option in your cell phone contract. If you cancel early and pay the option, you did nothing immoral. In a mortgage contract there is also an early cancellation option where you just pay the bank what you owe them and exit the contract without doing anything immoral. If you deadbeat either one of them, breaking the contract and failing to pay what you owe, it is IMMORAL rather than moral.
Pretending that you think defaulting on a loan is just taking advantage of a contract option is about as intellectually dishonest a pretense as there can be.