Be careful here... In most countries, it is illegal for private citizens to jam cell-phone transmission, but some countries are allowing businesses and government organizations to install jammers in areas where cell-phone use is seen as a public nuisance. In December 2004, France legalized cell-phone jammers in movie theaters, concert halls and other places with performances. France is finalizing technology that will let calls to emergency services go through. India has installed jammers in parliament and some prisons. It has been reported that universities in Italy have adopted the technology to prevent cheating. Students were taking photos of tests with their camera phones and sending them to classmates. So what we see is that even if it's maybe illegal the government reserves the right to do it anyway. As does any large organization with lots of lawyers. FCC rule 15 leaves a lot of room for interpretation and of course nobody does interpretation better than a lawyer. On the other hand the FCC would first have to file charges, which would be very un-likely if you were doing it ninja style.