The carrier had planned to offer calls over Wi-Fi last month in conjunction with iOS 9 but those plans were held up.
The FCC requires that call services provide support for the hard of hearing under TTY rules so AT&T requested a waiver for tose rules back in June. A 45 day comment cycle came and went with no negative comments, yet the FCC didn't grant the waiver until now.
AT&T last week said that it didn't understand why or how rivals Sprint and T-Mobile could offer Wi-Fi calling since they don't have such waivers.
Even though AT&T is now moving forward with Wi-Fi calling -- there's no timetable yet but it should be soon -- it's still grousing about its rivals, saying "[W]e are left scratching our heads as to why the FCC still seems intent on excusing the behavior of T-Mobile and Sprint, who have been offering these services without a waiver for quite some time."