AT&T Mobility (NYSE: T) said it continues to work with several smaller carriers, likely including T-Mobile US (NYSE:TMUS) and U.S. Cellular (NYSE:USM), to create roaming between different 700 MHz band classes but is still encountering some hurdles. Nevertheless, in delivering a progress report on its 700 MHz interoperability efforts to the FCC, AT&T noted that it has turned on the feature in its network that lets its network operate simultaneously in both Band 12 and Band 17 and support devices in both band classes.

AT&T had pushed for the creation of its own Band Class 17 and previously argued it could not support Band Class 17 alongside Band Class 12 because it would be too expensive and would cause interference. However, in September 2013, AT&T agreed to reverse its position and support both Band Class 17 alongside Band Class 12. Specifically, the company said it will develop, implement and deploy throughout its network multi-frequency band indicator (MFBI) capabilities to support the interoperability.

In a filing with the FCC AT&T made in September, AT&T said that as of Aug. 14, 2015, the MFBI feature had been "fully deployed on our macro-cellular network and we are transmitting both Band 17 and Band 12 throughout the AT&T Network. In addition, we have completed testing and activation of the MFBI feature on one of our small cell vendors." AT&T had until Sept. 30 to activate the MFBI capabilities on its network.

As of Aug 17, "all of the small cells in our network have been fully deployed with the MFBI feature and we are transmitting both Band 17 and Band 12 on these small cells. The second small cell vendor has not completed general availability of the MFBI feature and this product will not be deployed in the network until this feature successfully completes the testing." AT&T did not name the small cell vendors involved.

AT&T said that it continues to have discussions "with several Band 12 operators to stay aligned technically to support LTE roaming but are still encountering multiple issues associated with support of voice until the operators are fully deployed for VoLTE because of a lack of support for Circuit Switch Fallback capability. We are investigating the ability to support data only roaming but additional details need to be analyzed." Presumably, AT&T is talking about T-Mobile, U.S. Cellar and other smaller operators like C Spire Wireless that use Band 12.

AT&T noted in the filing that "the FCC's goal of promoting interoperability in the Lower 700 MHz spectrum by creating a robust Band 12 ecosystem has largely been accomplished. In the two years since the Order was adopted, carriers have increasingly deployed 700 MHz A block networks that rely on Band 12 devices."

Indeed, T-Mobile has said that of the 190 million POPs covered by T-Mobile's Band 12 700 MHz A Block spectrum, it has around 165 million deployed today. So far this year T-Mobile has added 400,000 square miles of LTE coverage and will add another 600,000 square miles by year end. Most of that will be through the continued deployment of the 700 MHz spectrum in rural areas, which is opening up new market opportunities for T-Mobile where it did not have a network presence before.

T-Mobile also is selling 16 smartphones and four tablets that support Band 12 capabilities. Apple's (NASDAQ: AAPL) new iPhones 6s and 6s Plus support Band 12, which T-Mobile has made a major selling point.

AT&T said that "many of our devices have been sold with Band 12 filters and can be upgraded via software to support Band 12. We will begin the process of transitioning to Band 12 late in 2015 and/or early 2016."

AT&T also noted that U.S. Cellular, through its partner King Street Wireless, has enabled LTE on 700 MHz Band 12 in more than 100 markets nationwide. U.S. Cellular is continuing to deploy its LTE network and aims to have 98 percent of its customers covered with LTE by the end of 2015. U.S. Cellular CEO Ken Meyers said at the end of July that customers will be able to start benefiting from expanded LTE roaming in the next 60 to 90s days. The partner is likely a Tier 1 carrier, so U.S. Cellular customers will get access to a more robust and nationwide LTE network.

For more:

- see this FCC filing



Related articles:

T-Mobile jabs at Verizon in new ad that highlights its 700 MHz LTE coverage expansion

T-Mobile, CCA tangle with AT&T over 700 MHz purchase as AT&T pushes for deal to go through

AT&T makes progress on 700 MHz interoperability, likely benefiting T-Mobile

AT&T unveils LTE phones that support 700 MHz spectrum it got from Qualcomm

AT&T, Dish, CCA cheer FCC's official stamp on 700 MHz interoperability deal