Samsung Galaxy S4 I9500 16GB Unlocked GSM Octa-Core Smartphone w/ 13MP Camera - Black GSM 850 / 900 / 1800 / 1900, 3G: HSDPA 850 / 900 / 1900 / 2100 5.0" Super AMOLED Multi-Touchscreen w/ Corning Gorilla Glass 3 and TouchWiz UI Android v4.2 (JellyBean) OS (upgradable to v4.4.2 KitKat) 13 Megapixel Camera (4128 x 3096 pixels) + Front-Facing 2 Megapixel Camera 16GB storage, 2GB RAM + microSD Slot Expandable up to 64GB 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.