> Very true, I thought about that, and you know, that wouldn't work
> either. As we all know radio signals propagate, it is almost
> impossible to make a signal "stop" somewhere, the only way would be to
> surround the building in a faraday cage, in which case the jammer is
> unnecessary. So if they have

Jamming is based mostly on the inverse square law. The idea is that the
transmitter is much farther from the receiver than the jammer. So it needs
only a tiny fraction of its power. So little that a cunning selective
reflector wall of stamped aluminium or steel will shut the phones up good
when near it. The term 'multipath interference' means something to you
here ? ;-)

Peter

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