Trying to unlock a paid off phone but ATT system saying it has not been paid off
I have been trying to unlock my friends previous phone through AT&T unlock device online but it keeps telling me that I have to pay off the device first. Error message: "Looks like you haven't paid off your device yet. Follow these steps to pay off your installment plan. Then, wait 48 hours before you submit a new request.
This is an iPhone 6s and he lent it to me so that I could send off my other phone to get fixed and still have one in the meantime. I am not an AT&T customer but the phone is 100% paid off.
What should I do to get my old phone unlocked?