Our GPS trackers are so designed to communicate with the users in a seamless way using 2 main functions GPS and GSM.
GPS allows the device to communicate between itself and the Space satellites in order to ascertain the exact location of the device.
GSM is the technology behind most of our cell phone that allow us to communicate from mobile to mobile.
GPS and GSM work together to gather and send information through this process.
GPS gathers the information from the satellite and submits it to the unit; the device then interprets this information and sends it to your cell phone via GSM.
So, with this explained you may find that if you are located in Japan or Europe and your device is located in the United States you could still communicate with the device no matter the distance as long as your cell phone has reception.