Companies like AT&T generally aren't in the business of making it easier for customers to switch to competitors. But a new plan from the company will do just that.

Potentially resolving battles between AT&T and competitors over interoperability in the 700MHz band, AT&T informed the Federal Communications Commission (FCC) yesterday that it intends to revamp its LTE network to be interoperable with networks of smaller carriers. As a result, a customer could switch from AT&T to a smaller carrier such as US Cellular or C Spire and be able to use the new network and roam on AT&T's network.

"This makes it possible for AT&T customers to maintain their devices if they were to switch to a smaller wireless carrier," Public Knowledge CEO Gigi Sohn said in a statement. "Enabling standards of interoperability at the lower 700MHz band gives consumers the chance to use their devices with large and small wireless carriers without purchasing a new device."

The agreement ends a four-year dispute, according to the Competitive Carriers Association. The group praised FCC Acting Chairwoman Mignon Clyburn for getting it done. "In particular, lower A block licensees like US Cellular and C Spire Wireless will finally be able to use all of their lower 700 MHz spectrum, unleashing investment and innovation, helping to achieve the Administration’s goal of universal access to mobile broadband," the Competitive Carriers Association wrote. "In turn, every consumer, especially rural and disadvantaged consumers who lack access to high-speed broadband, will benefit from her efforts.”

Competitors had asked the FCC to make the entire 700MHz band interoperable, according to an article on DSLReports. Besides solving the roaming problem, a lack of interoperability makes it less likely that handset makers will build devices that work with smaller carriers' networks, they argued. "AT&T long fought the changes, citing 'interference concerns' competitors argued didn't exist," DSLReports noted.

AT&T's FCC filing explains that it will support both Band 12 and Band 17 devices going forward, helping smaller carriers that use Band 12.

AT&T, which also just bought some more spectrum from Verizon, writes that its "700 MHz LTE network, which is expected to provide coverage to nearly 270 million consumers in 400 markets by the end of 2013, currently supports only Band 17 devices. Band 12 support on AT&T’s network will require that AT&T deploy a new network technology that will permit simultaneous support of both Band 12 and Band 17 devices. Absent this dual support, millions of pre-existing Band 17 devices currently in use by AT&T’s customers would be stranded.

"To achieve this, AT&T must develop, implement, and deploy throughout its network Multi-Frequency Band Indicator or MFBI capabilities. MFBI will permit AT&T’s network to operate simultaneously as both a Band 12 and Band 17 network and to support devices in both bands."

This can be implemented with a software update. AT&T promises to fully deploy the system within two years. In the first year, 50 percent of new devices on the spectrum will work in Band 12.

The promises are contingent on interference concerns being addressed. "AT&T reserves the right, in its sole discretion, to plan and manage lower 700 MHz interoperability support in a manner that will not disrupt existing services, strand existing devices, or result in unnecessary cost or delay," the company said.

But it's still "a big win for consumers, especially in rural areas, who will see more competition and more choices," Clyburn said.