The device is factory unlocked and guaranteed to work with all Major US Carriers; AT&T, Verizon & T-Mobile & minor carriers*. *Some minor carriers MetroPCS, Boost, Straight Talk, Xfinity, Cricket.. etc. may require the device IMEI to be registered in their system, and/or the network setting updated before the device can be activated on the network. It is the buyer's sole responsibility to confirm the device's compatibility with their network. Two months (60 Days) Seller Warranty from the delivery date for repair or replacement. The warranty covers manufacturer defects and does NOT cover accidental damage. Samsung Galaxy S20 Ultra 128GB