According to FCC filings, Qualcomm is developing a chip that could resolve interoperability problems on the 700MHz spectrum band, but the issue isn't fixed yet. The 700MHz block is currently used by AT&T, Verizon, and smaller US carriers, but they operate on different blocks, and regional carriers have complained about not being able to get hardware that operates on their bands or being unable to let their phones roam on larger networks. A new chip apparently being sped through development by Qualcomm, however, could solve these problems. In the filing, Qualcomm said its chip could be configured by manufacturers to work on a carrier's normal band but roam on a different one. At the same time, it says there are "significant device limitations" to the technique that mean it shouldn't be required for phones.

The company is hoping to stop the FCC from mandating that devices be somehow interoperable between different blocks, a proposal the agency has recently started acting on. "Because of the difficult interference challenges described herein, the fact that existing technology does not offer a solution to these challenges, and Qualcomm's ongoing innovation and collaboration with all carriers and manufacturers," it writes, "the commission should not require mobile equipment to be capable of operating over all paired commercial spectrum blocks in the Lower 700 MHz band." It also says the new chips will begin shipping to manufacturers by July and should be in devices at the end of the year.