When T-Mobile announced that it had an "exclusive" on the Nokia Lumia 810, we found the differences between it and the Lumia 820 so minor that it was hard to take the exclusivity seriously. Nevertheless, when T-Mobile put a unit on the table at MobileCon we felt it our duty to take a look, even though it wouldn't power on. The 810 is not a small phone by any stretch: the bezels are large, the corners much squarer, and the thickness is noticeable. It's 11.2mm thick, according to T-Mobile, a full 1mm thicker than the 820. The reasoning is ostensibly that the back cover is removable and can be swapped for another color, each of which includes the necessary electronics for wireless charging. The thinner 820 has the same feature, however, and a higher level of build quality overall.
The specs are the same as the 820, including a 4.3-inch display, but there are enough hardware differences to convince us that this is indeed a different phone. In addition to the obvious thickness difference, there are lots of other subtle variations here: the camera and flash placement, microSD slot, and charging contacts are all shifted; moving components around like that usually amounts to more than just an aesthetic decision. Looking at the differences, it's hard not to speculate that the "exclusive" T-Mobile actually snagged is a phone that is slightly cheaper to produce. Whether that will translate into a cheaper retail price is another matter — like virtually every other device at MobileCon, there's no official price or release date for the Lumia 810.