RE: 2.4 ghz Jammers
I could not find the article, but there was a church that got busted for installing just such a jamming device. Apparently whoever was in charge at the church was irritated by peoples phones and their bluetooth stuff and installed it. I would think asking that they be turned off would have been a better choice.
I never heard the outcome of the case but at the time of the article the operator of the illegal device was facing some pretty hefty fines.