This is from Motorola's website
Network Bands - US GSM Unlocked:
GSM/GPRS/EDGE (850, 900, 1800, 1900 MHz)
UMTS/HSPA+ (850, 900, 1700, 1900, 2100 MHz)
4G LTE (B1, 2, 3, 4, 5, 7, 8, 12, 17, 19, 20, 28, 38, 40)
I've only been using mine for a day on AT&T and haven't travelled around much with it...