LTE MIMO; GSM/EDGE: Quad-band (850/900/1800/1900 Hz), Class 12; UMTS: Tri-band (UMTS 850/1900/2100MHz), HSPA+Category 14xx (HSDPA 21Mbps/ EDCH 5.7 Mbps) this is what you would need for at&t LTE. I also have the developer edition but it came from HTC U.S.
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