2023:Can't Enable “Add Wi-Fi Calling for Other Devices”

It appears an old problem is back.

So I've been dealing with this for SIX YEARS, so I do not need boilerplate "I understand..." answers.

In the past week, I cannot activate WIFI CALLING ON OTHER DEVICES (iPad, Mac).

It ONLY works "when nearby", which is just Bluetooth calling. 

I have:

1. Restarted phone 15x (and restarted other devices; took them off wifi; turned everything off)

2. Called AT&T, spoke to support for 45 minutes, disabled Wi-Fi calling, re-enabled Wi-Fi calling.

3. Did same for NumberSync for Apple.

4. Reset Network Settings on my phone (what a nightmare that will be in the future)

5. Replaced the entire eSIM (again this will be a future nightmare)

NOTE 1 - my WATCH can make calls without connection to my phone - but all OTHER 'NumberSync' (Wi-Fi calling) devices CANNOT.

NOTE 2 - trying SECOND SIM also fails - WiFi calling ON PHONE works; for OTHER DEVICES fails. Period.

Apple points finger at AT&T (carrier). AT&T points finger at Apple.