A:Answer Both SIM slots support 2G,3G, 4G and LTE but only one may be used as 3G,4G,LTE at a time. You can select which one to use for data in the phone settings without rebooting so you don't need to pop out the SIM tray to switch the LTE sim back and forth. Works great where you have one sim for one country and vice versa. You can swap your default data sim in software and the apps never even realize that you have switched the carrier.