Although AT&T has never mentioned anything about carrying the Nokia Lumia 520, the smartphone might one day land on the carrier's shelves. Or at least that's what we're inclined to believe now that a Nokia Lumia 520 variant with AT&T-friendly 3G bands has been spotted at the FCC. This particular device carriers the model name RM-915, meaning that it's different from the RM-914 model, which is tailored for Europe and Asia.
The Nokia Lumia 520 is bound to launch internationally in April, meaning that if AT&T is really going to offer the device, it might release it around that time. A variant of it is headed to T-Mobile bearing the Lumia 521 moniker and (presumably) a low price tag.