VoWifi not working on Fairphone 3+

• /e/ version: 0.21-20220121158536
• Device model(s): Fairphone 3+
• Device rooted: yes

Summary

VoWiFi (WiFi calling) is active but not working

The problem

Steps to reproduce

• ensure VoWiFi is on
• activate airplane mode
• switch on WiFi
• place a phone call

What is the current behavior? Phone give me the error: “Mobile Network is not available. Connect to a wireless network to make a call.”

• WiFi is active, connection to the Internet is working

What is the expected correct behavior? The device should establish a connection via activated WiFi.

The same error has also been reported by users of other devices: https://community.e.foundation/t/when-trying-to-use-wifi-calling-while-connected-to-wifi-phone-asks-to-connect-to-a-wireless-network/37772