I am assuming that even though the device is not financed by AT&T (instead financed by Citizens One), it is still locked to AT&T until AT&T unlocks it. Is that correct?
Will AT&T unlock the phones you purchase through Apple's iPhone Upgrade Program?
The iPhone will arrive unlocked with an AT&T SIM if purchased through Apple's iPhone Upgrade Program. Apple iPhone Upgrade Program
$34.50/mo. for 24 mo.
Unlocked iPhone with AT&T SIM