SOS mode - get it off my iPhone 13 Pro!

SOS means that your phone is working, but is not connected to your carrier’s network. It can only make emergency calls on other networks. You need to contact your carrier to resolve this. Here is guidance from Apple→If you see No Service, Searching, or SOS on your iPhone or iPad

If you see No Service or Searching in the status bar on your iPhone or iPad (Wi-Fi + Cellular), your device isn't connected to a cellular network. If you see SOS or "SOS only" in the status bar, your device can still make emergency calls.

If you see No Service, Searching, or SOS on your iPhone or iPad