The radios work independently of the mobile phone network. Radio transmission is via a frequency of 446 MHz directly from device to device (without transmission masts). All comparable devices (also from other manufacturers) with the PMR446 standard can receive the radio within range - as long as the devices have the exact same channel set. With the 8 channels and 121 subchannels each, this is very unlikely. Range depending on the environment (open area, building, forest) up to 10km between the two devices.