on cell phones, car stereos, radios and most any other electronic device that sends or recieves any sort of signal, its govt law that they adhere to certain "standards". One such standard, and it is usually printed on the back or underside of the device "This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions : (1) This device may not cause harmful interference, and (2) This device must accept any interference recieved, including interference that may cause undesired operation."
Ive noticed it for a long time, sounds like permission to spy to me.