The beta release of iOS 9 includes a Wi-Fi Calling feature specifically for AT&T Mobility customers. Until now, only T-Mobile and Sprint subscribers have had access to the service, which was added to iOS 8. According to MacRumors, AT&T has begun rolling out the service to a "limited number" of subscribers with iOS 9 installed on their iPhones.
Wi-Fi Calling can be enabled from Settings in the latest iOS 9 beta. Once the feature is activated, it takes a few minutes to become available. Users must enter an address in case of emergency, since calling over Wi-Fi does not deliver location information. After this process is complete, Wi-Fi calling can be toggled on or off at any time with a switch in the settings.
Once the public version of iOS 9 is released, AT&T customers will be able to make voice calls and send text messages using Wi-Fi when a cellular connection is not working. iPhone owners can already enjoy the clarity of Wi-Fi calling when using FaceTime to make voice calls. iMessage also uses a Wi-Fi connection when possible to send messages, photos and video. iOS 9 Wi-Fi Calling will provide a seamless incoming and outgoing connection for regular calls and text messages.
Starting with the iPhone 5, wideband audio is possible with carrier support. The difference in quality between traditional cellular calls when compared to Wi-Fi Calling or wideband audio is noticeable. Look for AT&T to complete the rollout of Wi-Fi Calling to iPhone owners over the next few months.