Fix poor call quality

Calls adapt to the connection they're on, but there's a floor.

Try these first

1. Move to Wi-Fi, or somewhere with a stronger mobile signal.
2. Turn video off — voice needs far less bandwidth.
3. Close other apps or tabs that are streaming or downloading.
4. On the web, check the browser has permission for your microphone and camera.

Nobody can hear you

Check you aren't muted in the call, that the right microphone is selected, and that no other app has grabbed it.

Calls don't ring

Make sure notifications are allowed for KT, the chat isn't muted, and — on the web — that the browser is allowed to show notifications, since a call arriving while the tab is in the background alerts you that way.