Z18 2.45 Inch Mini 3G Android 4.4 Smartphone with FM WiFi Black 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. SIM Card Quantity: Dual SIM this is a very small smartphone , size: 48 x 88 x 12.8 mm RAM:512MB ROM:4GB