Why can't I make calls or text on my iPhone after iOS 17.6.1 update?

I am in a remote field camp without cellular service and only Starlink for WiFi. Upon updating my iPhone to the latest (17.6.1) I lost the ability to call or text non-iPhone users, basically I can only FaceTime and iMessage. I contacted my service provider and talked to them and the problem seems to be with the phone or the update.

[Re-Titled by Moderator]