Samsung Galaxy Express I437 Unlocked GSM Phone with 4G, Android 4.0 OS, Dual-Core Processor, 4.5" Super AMOLED Multi-Touchscreen, 5MP Camera, GPS, Wi-Fi, Bluetooth, NFC and microSD Slot - Black GSM 850 / 900 / 1800 / 1900, 3G: HSDPA 850 / 1900 / 2100, 4G: LTE 700 MHz Class 17 / 1700 / 2100 Android OS, v4.0 (Ice Cream Sandwich), upgradable to v4.1 (Jelly Bean) Chipset: Qualcomm MSM8960 Snapdragon, CPU: Dual-core 1.5 GHz Krait, GPU: Adreno 225 5MP (2592 &#x445; 1944) pixels w/ autofocus, LED flash, Geo-tagging, touch focus, face detection + front-facing 1.3MP Camera, Video: 720p@30fps 8 GB (5 GB user available), 1 GB RAM + microSD slot expandable up to 32 GB 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.