Microsoft Lumia 640 XL GSM Single-SIM Unlocked Smartphone, Quad-Core, 8GB ROM, Windows 8.1 (White) Microsoft 640 XL is a Workforce Powerhouse at an affordable price it is GSM unlocked to work with any GSM network worldwide Storage: 8 GB ROM, 1 GB RAM microSD Card slot: up to 256 GB (dedicated slot) Reased: April 2015, (being that this is GSM unlocked you will need to contact your network provider to acquire a SIM card as there is no SIM card enclosed) DISPLAY: Type IPS LCD capacitive touchscreen, 16M colors, Size: 5.7 inches (~69.1% screen-to-body ratio) Resolution: 720 x 1280 pixels (~259 ppi pixel density) Multitouch Yes Protection Corning Gorilla Glass 3 - Clear Black display PLATFORM: OS Microsoft Windows Phone 8.1, upgradable to Microsoft Windows 10 Chipset: Qualcomm MSM8226 Snapdragon 400 CPU: Quad-core 1.2 GHz Cortex-A7 GPU: Adreno 305 Wireless Technology Bands Supported: 4G-LTE Bands 1, 2, 3, 4, 5, 7 and 17 4G HSPA+ with enhanced backhaul 3G - UMTS 850/900/1900/2100MHz GSM/GPRS/EDGE 850/900/1800/1900MHz 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