AT&T calls out T-Mobile, Sprint for offering WiFi calling without FCC approval

Apple's iOS 9 and new iPhones now have support for WiFi calling, a feature that lets users place voice calls over a WiFi connection instead of using cellular. US carriers Sprint and T-Mobile have already launched the feature on their networks, but some are wondering why AT&T hasn't when it was expected to debut with the iPhone 6s and 6s … Continue reading