AT&T and Verizon both recently came out against T-Mobile, asking the FCC to take action to prevent T-Mo’s spectrum portfolio from growing, and today T-Mo has responded.

First up, Verizon filed a petition to the FCC asking the agency to reconsider allowing T-Mobile to strike a 600MHz spectrum lease deal with Columbia Capital. Verizon argues that with these arrangements, T-Mo will exceed the FCC’s 250MHz screen for low- and mid-band spectrum in certain markets, including some where it already exceeds that screen by more than 100MHz.

“Concentration of needed spectrum in the hands of a single operator can raise serious competitive concerns and, over time, threaten the health and competitiveness of the wireless market,” Verizon says in its filing.

Meanwhile, AT&T made its own filing with the FCC in which it says that the T-Mobile-Sprint merger has “resulted in an unprecedented concentration of spectrum in the hands of one carrier.”

AT&T goes on to argue that the new T-Mobile exceeds the FCC’s spectrum screen in Cellular Market Areas representing 82 percent of the US population, which includes “all major markets”. AT&T asks the FCC to transparently re-evaluate its spectrum screen, including in cases where a company holds an amount of spectrum that’s in excess of that screen.

“If the spectrum screen is to continue to have meaning, the Commission needs to explain how it will be applied so there is some clarity on when, and under what circumstances, entities will be permitted to continue to amass holdings in excess of the screen,” said Joan Marsh, AT&T’s EVP of Regulatory and State External Affairs. “Absent such clarity, the screen will become an empty vessel.”

Today T-Mobile CEO Mike Sievert published a blog post in response to AT&T and Verizon’s complaints. He says that AT&T and Verizon are “feeling the heat of real competition” and that the other two major US carriers are “scrambling to block this new competition any way they can.”

Sievert argues that AT&T previously purchased the 600MHz spectrum that T-Mo is leasing from Columbia Capital but then didn’t want it and sold it back to Columbia, while Verizon “never bothered to even show up and bid for any 600MHz spectrum.” He also claims that AT&T and Verizon want to limit T-Mobile’s ability to bid against them in the FCC’s upcoming C-band spectrum auction.

The T-Mobile CEO then argues that the FCC’s spectrum screen doesn’t take into account how those additional airwaves could enable wireless carriers like T-Mo to use their networks to “provide genuine competition to the incumbent in-home broadband providers.” T-Mobile has been running a pilot for its home internet service that uses its wireless network, and that testing recently opened up to everyone in Grand Rapids, Mich.

So far, the FCC hasn’t gotten involved in this bickering between the major US carriers. The aforementioned C-band spectrum auction is getting close, though, with bidding scheduled to get underway on December 8, so it’ll be interesting to see what, if anything, comes of AT&T and Verizon’s complaints.

Sources: FCC (1), (2), AT&T, T-Mobile