Hi, French user on SFR network, I got VoLTE immediately but WiFi calling wasn't showing in the Settings. Operator's website showed that the option was subscribed for my account, so I looked for help on forums.
I found out that entering a shortcode in the dialer app (*#*#3642623344#*#*) enabled the feature and I got the menu to appear. I enabled WiFi calling and it worked perfectly (icon, settings, and calls). I can switch from VoLTE to VoWiFi or use either Home of Office WiFi network without any trouble for days/weeks, maybe months.
But every time I reboot the phone, the feature is disabled and I have to enter the shortcode again. Is there any way to make it permanent ?
Thanks !