TOTO&reg; Unlocked Quadband Dual Sim Android 4.1 Os with 5 Inch Touch Screen Smart Phone - At&t, T-mobile, H20, Simple Mobile and Other GSM Networks (Black) Unlocked Quad Band Dual SIM 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.