Yesterday, iOS 8.0.1 showed up and turned a whole bunch of new iPhones into iPod Touches. You can fix it now if you take the right steps, but the official patch from Apple might take a few days.
From Apple’s support page on the subject, which also walks you through the revert-to-iOS-8 process:
We are also preparing iOS 8.0.2 with a fix for the issue, and will release it as soon as it’s ready in the next few days.
With any luck that could be today or tomorrow, but Apple’s clearly building in room for a bigger gap. So if you’re left in the lurch, you’re going to have to take matters into your own hands.
https://gizmodo.com/how-to-go-back-to-ios-8-and-get-your-cell-service-worki-1638741282
