I know a couple of restaurants that purchased these kind of jammers. Although it brought peace and quiet, those on business duties (like doctors) quickly started avoiding the place. Their phones and beepers didn't work. I would avoid similar establishments. It should be offered as an open service, not a clandestine box for restaurant owners. That happy music makes it look like they are selling lollipops.
I suspect that authorities already use them at public demonstrations - have you seen how poor cell coverage is? Sometimes you also see very strong signals - so much so that I wonder if I am really connecting the right carrier signal. Just because it says Vodafone on the mobile screen is no guarantee is it?
I remember DATONG that used to build shortwave equipment for amateur radio operators (the Woodpecker filter), gave that up and went into building wireless networks of all kinds. David A Tong came up to Durham university in 1980 to explain about the company then. Very different to today.