We all know the story: The Nexus 4 borrows parts from the Optimus G it’s based on, thus it has an LTE chip. And it lacks other hardware necessary for using LTE in full. However, people got LTE working on a specific band. Here’s a surprise for you: AT&T owns that band in a few areas. Their LTE is mostly on Band 17, which is 700 MHz, but a few select areas use band 4 at 1700 MHz.
The few areas where AT&T owns that spectrum are Phoenix, Raleigh, San Juan, Los Angeles, Las Vegas, Oklahoma City, Dallas, Chicago, Charlotte, Athens, GA and College Station, TX. That does not mean that you’ll get LTE in those areas. Though AT&T owns that spectrum, it doesn’t mean that they use it. However, someone did manage to catch an LTE signal on AT&T with the Nexus 4, so keep your hopes very low but alive.