AT&T is facing off against a number of regional providers over proposals to establish interoperability in the lower 700 MHz band.

Many smaller operators say the incompatibility between the two classes of spectrum in the lower portion of the 700 MHz band makes it almost impossible to obtain the equipment and devices they need to deploy LTE.

They want the FCC to collapse the lower 700 MHz into a single band class so that their LTE services can run on the same gear as AT&T's network, giving them access to more widely available infrastructure and smartphones.

The FCC agreed to explore the issue this spring. With the comment period now drawing to a close, AT&T is again voicing its opposition to the collapse of the lower 700 MHz band into a single band class.

"The proposed elimination of Band 17 would be profoundly poor public policy," AT&T regulatory affairs executive Joan Marsh wrote yesterday in a post on the company's public policy blog. AT&T's lower 700 MHz B-block and C-block spectrum is classified as Band 17, separate and incompatible from the Band 12 class containing the lower 700 MHz A-block, B-block and C-block. Development of the ecosystem for AT&T's Band 17 spectrum has surpassed that of Band 12, the band class owned by many regional providers.

Calling the proposed interoperability mandate "pointless," AT&T argued that smaller providers with Band 12 spectrum were perfectly capable of procuring devices without such a requirement, pointing to U.S. Cellular's LTE deployment on its Band 12 holdings.

But other operators with Band 12 spectrum, notably C Spire Wireless, have said their inability to get equipment and phones has made an LTE deployment on their 700 MHz licenses infeasible. C Spire has abandoned its near-term plans to use its 700 MHz spectrum for LTE. When its LTE network launches in September, it will be running on spectrum repurposed from its existing services.

"The current lack of interoperability has effectively deprived competitive wireless carriers of access to handsets that operate in the lower 700 MHz A-block, thus severely – and unnecessarily – restricting the ability of these carriers to provide consumers with competitive alternatives to the nation’s two largest carriers," regional provider SouthernLINC Wireless told the FCC this week.

AT&T also argued that an interoperability mandate would not address a major impediment to deployment in the lower A-block: interference from Channel 51 television broadcasts in the adjacent band, an issue which has rendered the lower A-block unusable in many top metropolitan markets.

Regional providers concede that Channel 51 interference is problematic but say AT&T's argument is a red herring designed to deter the FCC from moving forward on the interoperability issue.

AT&T has also claimed establishing interoperability will open it to interference issues it was formerly protected from. A group of regional providers, including MetroPCS, sought to rebut that claim in a study filed with the FCC last week.

"There is no meaningful performance differential between Band 12 and Band 17 devices that can reasonably be expected to result in harmful interference," they said in the report.

The FCC has not indicated whether it will move forward with an interoperability mandate. The comment period on its inquiry into the issue closed Monday.