US operator AT&T accused rivals Sprint and T-Mobile of breaking Federal Communications Commission (FCC) rules in launching Wi-Fi calling, while expressing exasperation that the US regulator has yet to approve AT&T’s own service.

The nub of the issue, according to AT&T,  is that the commission rules require all voice services, including Wi-Fi calling, to support teletypewriter (TTY) devices used by the disabled community. However TTY devices do not work reliably on IP-based networks, so requiring a workaround.

AT&T made clear its frustration in a letter to FCC chief Tom Wheeler, which it published.

While AT&T held off launching a service and developed a workaround to the problem, rivals T-Mobile US and Sprint jumped in with their Wi-Fi calling offerings.

AT&T came up with a technical alternative to TTY for IP-based Wi-Fi calls while asking for temporary waiver of rules so that its solution could be implemented. The alternative approach is called real-time text (RTT).

The company then filed a petition for waiver of the commission’s TTY rules, as well as a petition for rulemaking proposing the commission amend rules so RTT could be deployed in place of TTY.

Both filings took place in June, as AT&T made clear its target for a commercial launch of Wi-Fi calling in September but has been forced to hold back its launch as it waits for FCC approval.

AT&T vented its frustration in a letter to FCC chief Tom Wheeler, which it published.

It’s not fair
AT&T complained that the FCC moved too slowly in its consideration of its two petitions. The regulator did not respond with a public notice for six weeks, and then established a 45-day comment cycle.

AT&T was due to go live with its service on 25 September but is still waiting for an FCC waiver so has been unable to launch, even while its rivals are happily providing rival services.

The company also has a wider griper: “There is a growing concern at AT&T that there is an asymmetry in the application of federal regulations to AT&T on the one hand and its marketplace competitors on the other hand”.

It said the waiver may be delayed in part because the FCC is looking for an industry-wide waiver and not just for the company.

“While we appreciate the commission’s efforts here to expedite review, we renew our call for expedited action on AT&T’s waiver, without the delays attendant in crafting an industry-wide waiver”.