AT&T has finally enabled WiFi Calling on its network

It’s a real pain when you drop a phone call because you’re in an area with spotty cellular coverage. It’s even more annoying when it happens to be where you spend a lot of your time, like at home or at work. What good is a smartphone that can’t reliably make calls in the places you spend most of your time? Regardless of whether this is a constant concern for you or not, the outage can and will have a negative effect on battery life every time you make a call in a weak-coverage area.

With WiFi Calling, that problem is no more, because your iPhone can use your internet connection to place the call instead of using your carrier’s cellular network, and it works really well. Apple added support for WiFi Calling in iOS 8, and while some people have been able to take advantage of it, those in the United States only had that option if they were using T-Mobile as their carrier. Now, with AT&T joining the fray, many more people can now use WiFi Calling on their iPhone, and here’s what you need to do to enable it.
Step 1: Launch the Settings app.
Step 2: Tap Phone, then Wi-Fi Calling.
Step 3: Switch ‘Wi-Fi Calling on This iPhone’ to On.

Step 4: Tap Continue on the pop-up that appears.
Step 5: Read through the Terms of Service and accept them.
Step 6: Enter an emergency contact address for 911 calls.
Step 7: Tap OK and you’re done.
Now, when you’re on a WiFi connection with enough bandwidth, your iPhone will use that to make and receive calls instead of the cellular network. Be gone, spotty coverage and dropped calls!
Welcome to the future.

Source: http://www.redmondpie.com/how-to-enable-att-wifi-calling-on-iphone/