HTC’s gem from the Mobile World Congress show late last month in Barcelona Spain, the HTC One X, has been approved by the FCC for operating on AT&T’s HSPA+ bands. Unfortunately AT&T isn’t picking the GSM/HSPA+ version up.
AT&T will get the HTC One X with the qualcomm processor for their 4G/LTE network. Nvidia’s Tegra 3 processor doesn’t play nice with 4G/LTE which is why the switch to the Qualcomm, dual core chipset.
This FCC approval simply means that it’s approved for operation on AT&T bands. To acquire the device you will need to import it from overseas.
This also means it’s approved for Rogers bands in Canada. Rogers is on the list of carriers partnered for the HTC One series phones. It’s possible that Rogers will get the GSM version of the device.