Greetings —
Actually... Wi-Fi calling does work. Try the following:
- Slide up the Control Centre, hit the ✳️ cellular button to turn it off, wait a moment and make a call. As it connects, "Wi-Fi" returns to the right of the carrier name. End the call, and it disappears. But it's still active for both inbound and outbound calls.
- Now — turn on ✈️ mode and hit the Wi-Fi button (and BT too if you dare) to turn them off, wait a moment and turn Wi-Fi back on. "Wi-Fi" returns to the right of the carrier name — and stays there.
- But wait — there's more! With calling from other devices enabled (before you turn cellular off, of course) making calls is a breeze on other devices via Wi-Fi calling on the iPhone using FaceTime® on an iPad Air, for example.
In addition, iMessage does indeed work. With the just-returned iMessage iCloud sync disabled on all devices which is my preference, iMessages still sync between all devices logged into the same iCloud account as before. So does the call log on all iPhones (I have four). Delete a message and it'll delete locally only as it's meant to do with sync off.
Devices used — iPhone 7 Plus, iPhone 6, iPad Air, Space Gray 15-inch MacBook Pro 2017 with Touch Bar, iMac 27 2011, iMac 27 5K, Apple Watch Series 0, 2 and 3, and who knows what else.
Hope this helps.
Cheers!
JA