A bit of detective work can certainly go a long way. Some little-known sections of Nokia's Windows Phone diagnostics app were found by Nanapho as it analyzed its XAP file, lending credence to rumors that AT&T-branded Lumia phones are being tested at present time. The site uncovered screens dealing with "LTE TX" and "LTE Band Lock," with the latter adding references to Band 4 and Band 17 -- AT&T-specific radios. The last interesting piece of evidence was dug up in the MMS settings tool, which offers code that refers to CDMA. We've heard past rumors suggesting Verizon would be getting a Lumia as well, but there were no indications that LTE Band 13 is in testing here; Big Red is reportedly hesitant to launch new Windows Phones without 4G connectivity now, so choosing to go without it would suggest the carrier is willing to make a few compromises in the hopes of adding the Lumia to its ranks. Hopefully we'll find more clues in the days leading up to CES.