Samsung Focus S I937 16GB 4G HSPA+ Unlocked GSM Windows 7.5 Smartphone w/ 8MP Camera - Black GSM 850 / 900 / 1800 / 1900, 3G Network: HSDPA 850 / 1900 / 2100, 4G: HSPA+ 850 / 1900 4.3" Super AMOLED Plus Capacitive Multi-Touchscreen Microsoft Windows Phone 7.5 Mango OS, 1.4 GHz Scorpion Processor 8 Megapixel Camera (3264 x 2448 pixels) w/ Autofocus, LED flash + Front-Facing 1.3 Megapixel Camera + Video 720p Internal Memory: 16GB, 512 MB RAM 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.