The U.S. Federal Communications Commission (FCC) has granted AT&T’s request for a waiver allowing it to proceed with its WiFi calling plans.

The waiver allows AT&T to delay implementing a teletypewriter service for the deaf until December 2017. The Teletypewriter service does not work well with WiFi.

AT&T plans the newer real-time text.

In requesting the waiver, AT&T questioned whether or not the FCC was showing favoritism to other carriers. It noted that Sprint and T-Mobile both launched their calling over WiFi services without obtaining FCC permission.

AT&T’s Jim Cicconi, senior executive vice president of external and legislative affairs said in a statement:

“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.”

While AT&T has not named a date when the WiFi calling feature will be availalbe, it’s likely to be soon, since it already demonstrated the service.