A but if a catch 22 at this point.

Right now your best option is to pull that phones SIM card and toss it in a android phone and see if you can get the number off it and call that number.

Or you can try to out your sim in it and see if Siri voice dial for call mom/dad/spouse/husband/wife will work but if they sent a erase command giving it internet connection might invoke said erase command.

Alternatively if they enabled lock with a message giving it internet might cause their message if “If lost return to …” to pop up.

Or just take it back to a ATT stir and explain again what happened. This time don’t ask them to look into it simply say you want to help get it back to the owners and are leaving it with them. Set it down and walk out.

Once it’s theirs and your gone a manager MIGHT try to look into it before they toss it.

They are also Type 1 or whatever documentation. Which means a lot of times you can show only a passport instead of multiple types of id and they are in the same class or above the new Real ID things some states are starting to require for even domestic travel.