Nokia Lumia 900 16GB Unlocked GSM 4G LTE Windows 7.5 Smartphone w/ 8MP Camera - Black - AT&T - No Warranty 2G: GSM 850 / 900 / 1800 / 1900, 3G: HSDPA 850 / 1900 / 2100, 4G: LTE 700 MHz Class 17 / 1700 / 2100 4.3" AMOLED Capacitive Multi-Touchscreen w/ Nokia ClearBlack display and Protective Corning Gorilla Glass Microsoft Windows 7.5 (Mango), 1.4 GHz Scorpion Processor, Chipset: Qualcomm APQ855 Snapdragon, Adreno 205 Graphics 8 Megapixel Camera (3264 x 2448 pixels) w/ Carl Zeiss Optics & Dual-LED Flash + Front-Facing 1.3 Megapixel Camera Internal Memory: 16GB, 512 MB RAM (not expandable) Unlocked cell phones are compatible with GSM carriers like AT&T and T-Mobile as well as with GSM SIM cards (e.g. H20, Straight Talk, and select prepaid carriers). Unlocked cell phones will not work with CDMA Carriers like Sprint, Verizon, Boost or Virgin.