I just flew Korean air/Delta to the US Delta flight was great. Korean air fell short. Neither of us was asked about visas. Maybe on our return to BKK. We have multi entry Non O visas
I have AT&T. I have a very cheap plan and no insurance on my phone. I keep it turned off most of the time. They have a 10.00 a day calls and text. I respond to texts and make some business calls about twice a month when I know I will be needing a verification code.