RM-917. It may not sound like much on the outside, but the model number and above picture correspond with the Nokia Lumia 521, T-Mobile's version of the lower-end Lumia 520 announced at MWC last month. We still don't have any details on when it'll show up on retail shelves, but it's at least made its way through one of the final barriers to entry: the FCC approval process. As you might expect, the docs are low on details, but the frequencies support 850 / AWS / 1900 HSPA+ / UMTS as well as quadband GSM / EDGE. To refresh your memory, the 520 will sport a 4-inch WVGA LCD panel, 512MB RAM, a 5MP camera, microSD storage and quite a few other respectable goodies. Head to the source if you're a sucker for numbers and acronyms.