Sudroid Mini 2.45 " IPS Touch Screen Mobile Phone the World's Smallest Android Smartphone Dual Sim Quadband 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.