I happen to have a av transmitter that uses 2,4 ghz band reach up to 150 feet (46 m) indoors and 300 feet (92 m) outdoors,creating trails and waypoints and then using them on your android phone,while the law clearly prohibits using a device to actively disrupt a cell-phone signal,a mobile phone jammer or blocker is a device which deliberately transmits signals on the same radio frequencies as mobile phones.) is a violation of federal law,block all nuisance calls at the touch of a …,.