Getting started
Basic use
Calls and contacts
Messaging
Apps and media
Connectivity
Specifications
Cause 2 of 3: Your phone's software hasn't been updated to the latest version
If you can't use Wi-Fi calling, you may need to update the phone software to the latest version.
Solution: Update your phone with the latest software.
Find "About phone"
Press Settings.
Press About phone.
Update phone software
Press MIUI version. If a new software version is available, it's displayed. Follow the instructions on the screen to update the phone software.
Or choose...