One response mentioned reinstalling iOS, but I don't see an option for that anywhere. It just takes me I have the most current version.
When I have "full" WiFi and no service, my phone just says No Service and I can't make or receive calls. It used to say iD Wifi (or something similar).
I've already tried restarting the phone. I have an iPhone 7+, on iOS 12.1.2 (the latest version), & iD 35.1
Best answer by terrywebbs
Goto settings/wifi and turn wifi off [not wifi-calling] wait a while then turn it back on again, this resolves it for me! [Do not toggle wifi off from the widget menu this only disconnects the wifi]
Follow these steps if you can't turn on Wi-Fi Calling or make a Wi-Fi call. Wait two minutes before you go from one step to the next.
- Go to Settings > Phone > Wi-Fi Calling and make sure that Wi-Fi Calling is on.
- Restart your iPhone.
- Connect to a different Wi-Fi network. Not all Wi-Fi networks work with Wi-Fi Calling.
- Turn Wi-Fi Calling off and then on again.
- Go to Settings > General > Reset and tap Reset Network Settings.
You could try going to general and update and accept any new carrier settings that are available, a few weeks back there was an update and new carrier settings released.