Nokia Lumia 521 GSM Unlocked Windows Smartphone - White (Certified Refurbished) This Certified Refurbished product is tested and certified to look and work like new. The product ships with all relevant accessories and a minimum 90-day warranty. Mobile Operating System: Windows Phone 8 Color: White, Display: 4-inches Touch Screen: Yes, Built-in Digital Camera: Yes, 5-MP 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.