Try this. Tap the
1. phone icon
2. tap the menu icon
3. tap settings
4. tap the status switch beside wi-fi calling.
5. tap turn on, then wi-fi calling.
Alternatively, you can type wifi calling in search in the settings. You will be able to toggle the wifi calling feature to on. Once you activate WiFi calling, you dial or text as usual. The routing of your call or text is handled automatically in the background. Hope this helps.