One of the big new anticipated features in the just-released iOS 9 is Wi-Fi calling for AT&T iPhone customers. Though Sprint and T-Mobile users have been able to use Wi-Fi calling on the iPhone for some time, AT&T and Verizon have yet to deploy it. Wi-Fi calling makes up for gaps or poor coverage in a carrier's phone service by offloading calls to a Wi-Fi network and routing them that way.
While Wi-Fi calling with AT&T iPhones was expected to be available broadly with the launch of iOS 9, the carrier now says that it is delaying the availability of it pending approval from the FCC. Those that had beta tested iOS 9 prior to launch have been able to use the feature and will continue to do so, according to the carrier.