TMobile lgg5s employ an app normally to sim unlock these devices. You can request a temporary unlock and or a permanent unlock when permanent is pressed and successfuly approved the app then requests reboot to finalize the unlock and deletes itself in most cases. Or hides itself. You may look in settings and apps and see it. But if att works on it. It's unlocked. Im about 99% sure they don't employ domestic and international unlocks like Sprint devices have in the past
---------- Post added at 07:02 PM ---------- Previous post was at 07:01 PM ----------
You meant a H830 device right?
Also as a side note. As long as the device fully supports the same frequency's of your international carrior you should be alright.