This may be hard to follow. One beauty of the phone is its "world phone" capabilities. But if the phone is outside the US, will an AT&T or T-Mobile SIM work, in roaming mode?

First, the phone has only been used on Page Plus, not Verizon, so Verizon probably won't unlock it. But even if unlocked, Verizon claims it cannot be used with an AT&T or T-Mobile SIM. I use T-Mobile while roaming in Europe, but it normally roams on the "Orange" network, so it isn't really on T-Mobile, right? Do you have knowledge about what to expect?