HTC 8X 8GB Unlocked GSM Windows 8 Smartphone - Blue Windows 8 Phone Dual Core 1.5 Ghz S4 Processor Integration with XBox 8GB Internal Memory & 8 Megapixel Camera AT&T Retail Package - Unlocked for use with ALL GSM Networks 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.