It seems to work, although somewhat intermittently and a with a little unexpected behavior. I've played around for parts of the day today, the most reliable approach seems to be placing the phone into Airplane Mode, turning the phone off, then on, turn on and connect Wi-Fi, turn on and connect to VPN back to the US, turn off Wi-Fi, wait a bit, turn in Wi-Fi and it'll auto-connect the VPN and "AT&T Wi-Fi" shows up a few seconds later. I say this is intermittent because it worked 80% of the time I tried to "force" it this way today. Every other approach I tried seems hit-or-miss and not repeatable. And, it tends to stay connected to AT&T Wi-Fi calling for hours, although it sometimes does drop. Interestingly, I can turn off the VPN and it'll stay on Wi-Fi calling usually for at least several minutes, but in one case for an hour. But, after I make one call, it drops to just Airplane Mode + Wi-Fi (no Wi-Fi Calling). I can also take it out of Airplane Mode, and it'll stay and show under Settings:Carrier "AT&T Wi-Fi". But, it'll drop seconds to minutes later and switch to a local roaming carrier on its own. Using this approach the iPhone acts as if it's in the US even though it's physically located somewhere internationally. It's weird though, I can make calls, but while they are ringing it shows "dial assist". When sending text messages, if I paste an image it'll be sent as an SMS but the text above/below are "blue" iMessages. I have been unsuccessful in initiating a Wi-Fi call this way without the VPN, although I can get the phone to briefly display "AT&T Wi-Fi" sometimes for a few seconds. It's just not long enough to do anything useful.