HTC 1 X Unlocked GSM Android Smartphone with Beats Audio Sound and Front-Facing Speakers - White Unlocked cell phones are compatible with GSM carriers SIM cards. 2G Network GSM 850 / 900 / 1800 / 1900 3G Network HSDPA 850 / 1900 / 2100 DISPLAY 4.7 inches, 8MP Primary Camera with LED flash, 1.3MP Secondary Camera OS Android OS, v4.0 Ice Cream SandwichInternal Memory 16GB, 12.1 GB internal storage available to user, 1 GB RAM, 1.5 GHz Qualcomm, Dual Core Processor 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.