VIEW WI-FI CALLING STATUS: Swipe down from the Notifcation bar, then select the Setting icon.
To access Wi-Fi Calling through the quick settings, swipe down from the notification bar, then select Wi-Fi Calling.
When your phone is connected to Wi-Fi, Wi-Fi Calling is on, and a cellular connection is unavailable or poor, you'll see the Wi-fi icon after AT&T in the status bar to indicate that calls will be carried over Wi-Fi.