I'm not sure if there's anything to this or not, but I just upgraded my Verizon iPhone 6+ to iOS 8.0.1 and now I'm getting no service with the AT&T SIM that was working fine before the upgrade. I put it into and took it out of airplane mode to no avail, but I haven't done much troubleshooting yet. It's possible that it's just a problem with my individual phone, but I wanted to post a quick warning to let you guys know to hold off for a bit in case this really is a global issue. That said, is there anyone else with a Verizon 6 or 6+ and an AT&T SIM that upgraded to iOS 8.0.1? And if so, are you seeing the same issue?