Previously my iPhone XR would randomly connect to XM Wi-Fi and incoming calls would sometimes connect but the phone would always revert to call failed disconnects on incoming calls. Shutting off Wi-Fi calling and then rebooting the phone would resolve the call disconnect problem. This was with carrier settings Xfinity Mobile 40.0.
After the last 3 months or so of just leaving Wi-Fi calling "off" because of the issues, I decided to see if they had miraculously fixed it.
Today (April 2) I checked to see if XFinity had updated the carrier settings. They are now at 41.0. I turned Wi-Fi calling on and the phone immediately locked on XM Wi-Fi and has not flaked out as before. Incoming calls have not been disconnected.
I learned previously that just turning off Wi-Fi calling without rebooting the phone didn't fix the issues. My iPhone XR is on iOS 13.4 with Carrier settings 41.0 (Settings -> General -> About -> Carrier). This looks very promising - I don't know if Apple fixed this in iOS 13.4 or Xfinity fixed their carrier settings. If the phone starts disconnecting calls again I'll update my post - FYI.
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