Invoxia Cellular GPS Tracker uses the brand new LTE-M (or LTE Cat M1) network, supported by AT&T in the USA. Your GPS Tracker will thus work anywhere where there is AT&T 4G coverage, except in the extra inhabited territories (Puerto Rico, the U.S. Virgin Islands, Guam, the Northern Mariana Islands, and American Samoa).
Please note that the product might not work where there is typically no cellphone coverage: in the mountains, in underground parking lots, within very thick walls etc.
Contrary to Bluetooth-only trackers, Invoxia Cellular GPS Tracker is completely standalone and will work even where there is no smartphones around.