My only concerns with this is that a trade in requires you to have an AT&T unlimited wireless plan.
Such plans goes for between $65 and $85 per month.
That is not a wireless plan you should be on if you're on limited or no income.
Additionally it requires you to sign up for a 36 month installment plan, and if you fail to pay for that, you will be debited the remaining sum of the cost of the phone. A installment plan you will most likely be forced to pay if you end up having to cancel your unlimited wireless plan. Which again, not the best idea to do when your income source is uncertain.
They're not just gonna give you a $800 - $1600 phone for free, you know.