Posh Mobile Orion S450 Android Smartphone Unlocked GSM Worldwide Dual SIM - Black GSM: GSM 850/900/1800/1900 Sim Card Slot: Dual SIM (1&2) Primary Camera: 5.0 MP 4G HSDPA+: 850/1900 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.