AT&T has recently delivered a progress report for the FCC with respect to the development of interoperability in the 700Mhz band necessary for LTE roaming support for smaller carriers using the the 700MHz A Block of spectrum on Band 12, which affects C Spire Wireless, U.S. Cellular and T-Mobile.
AT&T initially refused to support Band 12 LTE interoperability and roaming, citing added costs and interference with its own 700Mhz spectrum holdings on Band 17, but has changed course since 2013 and recently completed lab testing for the interoperability study.
The carrier has since confirmed that substantial progress is being made at the field testing level to enable support for Band 12 interoperability on its network, working with its hardware partners to complete the work necessary to enable support in the future through Multi-Frequency Band Indicator deployment and support.
AT&T is also citing recent changes to the 3GPP spectrum rules that will allow it to build, develop and deploy Band 12 compatibility through MFBI software updates for older Band 17-only devices as well as new hardware with proper hardware and software filtering for Band 12 support.
As a result, AT&T is committing to releasing updates for older devices and new devices with Band 12 support and expects that half of its lineup will feature Band 12 MFBI support by September 30th of this year, provided a mentioned 4-week delay with its hardware vendor is resolved before then.
AT&T also noted several phones in the report that will feature Band 12 support after the aforementioned software update, including the Samsung Galaxy Avant, ZTE ZMax, Sony Xperia Z3 and Motorola Nexus 6. The Samsung Galaxy Tab 4 8.0, Galaxy Tab S 10.5, along with the ZTE Z915 hotspot, currently support Band 12 at the hardware level but the band is currently unactivated on those devices and requires a software update to enable support.