Most of the times, news reports come down the wire talking about how carriers are attacking each other and always trying to get one up over the over. However, that is only at the customer level. At a more fundamental level, carriers do need to (and do) work together to try and bring a better level of product to everyone. This is more prominent in the carrier world than other industries, as they all use the same network. Yes, they operate on different bands and on different spectrum, but underneath interoperability between the bands and spectrum is better for all.
In terms of the 700mHz band, the idea of interoperability has been more important. This is because while AT&T operate on band 17 within the 700 MHz, a lot of smaller carriers, like U.S. Cellular work on band 12. It has been largely understood and argued that while big manufacturers manufacture devices compatible with AT&T's band 17 and even Verizon's band 13, few manufacture for band 12. Although, it is worth noting some devices, like the Samsung Galaxy Note 4 and Note Edge to work on both band 12 and band 17. Either way, in September 2013, AT&T agreed they would look to support band 12, as well as band 17 by developing multi-frequency band indicator (MFBI) for devices to work on both classes of bands.
Well, that was back in 2013 and last week AT&T released a filing which updated on the progress they were making with the project. The main point noted from the filing was that AT&T expect to be able to bring to market devices capable of working on both bands within the first half of this year. However, it was noted the progress was not completely without issues. According to the the AT&T filing and in terms of the MFBI's "well into our field testing for all of our Macro-cellular vendors and progressing well with the exception of one vendor that has run into multiple software issues on their 3G (UMTS) cells, requiring software fixes that will need to be retested through the lab".
No information was provided on who the vendor is. However, in spite of the obstacles, AT&T were noted stating that they expected no delays in terms of the rollout date for the MFBI's which is scheduled for September 2015. It is expected that T-Mobile will benefit somewhat when the service does rollout, due to their much-recorded focus on the 700MHz band. Thanks to the already in place agreement, T-Mobile will have 700MHz band coverage which effectively means their devices will able to roam AT&T LTE territory. You can read the full AT&T filing by clicking the source link below.