Though AT&T had Wi-Fi calling enabled through much of the iOS 9 beta program this summer, those who upgraded to the final version found that the feature was missing. The reason? It doesn't support teletype services (TTY) for the deaf and hard of hearing very well, which the FCC generally requires of wireless networks. In its place, AT&T wants to deploy real-time text (RTT), which it says is faster, richer, and generally better than TTY — a decades-old technology.

That roadblock has been cleared now with a waiver granted by the FCC that lets AT&T get around the RTT rule until the end of 2017. (AT&T doesn't yet have a time frame for flipping the switch back on for customers, but it shouldn't take long.) This isn't where the story ends, though: In the process of applying for a waiver AT&T was complaining about T-Mobile and Sprint, both of which launched Wi-Fi calling without an FCC exemption — in other words, as AT&T sees it, its competitors were offering their services in violation of FCC rules. It's still challenging them today, too. Says AT&T's Jim Cicconi:

We're grateful the FCC has granted AT&T's waiver request so we can begin providing Wi-Fi calling. At the same time we 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. Instead of initiating enforcement action against them, or at least opening an investigation, the agency has effectively invited them to now apply for similar waivers and implied that their prior flaunting of FCC rules will be ignored. This is exactly what we meant when our letter spoke of concerns about asymmetric regulation.

Then again, the only thing really stopping AT&T from moving forward before was its own self-regulation in the face of its competitors flouting the rules — the FCC hadn't stopped it. Had it felt rebellious, it could've deployed anyway, but the marketing value of calling out T-Mobile's transgressions might be far greater than enabling a feature that lies in a legal gray area.