If there are any others out there with a MacBookPro18,4 at 12.0.1, and an iPhone 13 Pro Max at 15.1 with two active numbers on dual SIM (US, not China version) who use T-Mobile post-paid cell service, would you please check and see if you can enable “Upgrade to Wifi Calling” in FaceTime as shown in the snippet below?
“Calls from iPhone” works as documented: I can call from FaceTime on my MBP as long as the iPhone is on the same WiFi network. But when the upgrade to WiFi is selected, nothing happens. It should connect FT on the MBP to the TMO account.
This worked like a charm on my iPhone 12 Pro Max on a 2020 MBP on Big Sur.
Calling either Apple or TMO is pointless – they can’t be made to understand the question over the phone.
I’m really just curious if it’s some combo of my hardware and software or if anyone else has seen this issue.