If you find that your call quality isn't as good as it should be, here are a few things you can try.
Check your phone is compatible with WiFi Calling. If your device isn't on this list, then it may be that your device (rather than SMARTY) doesn't support Wi-Fi calling.
It's important to be running the latest version of your device software
Ensure that WiFi is enabled on your phone, you can check your device settings for this or look for the Wi-Fi symbol
If you’re connected to a WiFi network, check that you can access the internet by trying different web pages.
For a good quality call, you'll need a speed of at least 2MB.
If your device shows that you’re connected to WiFi, try restarting the router, as the issue may be with your WiFi connection.
Remember, if you move between WiFi hotspots, this can sometimes cause disruption to your call.