Huawei Ascend G510-0251 Unlocked GSM Android Cell Phone - Black Cellular Band - Quad-Band 850 / 900 / 1800 / 1900 Mhz Cellular Band 3G - 850 / 1900 / 2100 Mhz 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. This cell phone may not include a US warranty as some manufacturers do not honor warranties for international version phones. Please contact the seller for specific warranty information.