There are a few possible reasons:
- VoWiFi requires an adequate Wi-Fi signal strength (with a minimum bandwidth of 25 kbps) before initiating the automatic connection to WiFi Calling. You can try to move to an area where the signal strength is stronger.
- If the WiFi network has a captive portal (Eg. Starbucks which requires a login), you may have to launch the browser and sign in to the network with the provided username/password.
- For public WiFi networks, the provider may have policies in place to block WiFi calling services.
- For private WiFi networks (e.g. company WiFi), the location may have policies in place to block WiFi calling services.
- Your device may not fulfil the prerequisites for Yoodo VoWiFi service.