What I mean: why is it not closed every day due to terrorist warnings by telephone?

Why does Al Quaeda not just call in an claim to have placed a bomb during rush hour? This would completely disrupt the life of the city for several hours and would cause a damage in the order of several million pounds. And the risk of getting caught is virtually zero … and even if they’d get caught the penalty would be ridiculously low.

Occasionally you have such “prank calls” at high schools. But even there one could ask: why not more often? I mean, if some troublemaker really hates the school, why does he not call every day to claim someone has placed a bomb? Maybe he does, maybe Al Quaeda does or would the same, but there must be some sort of filtering mechanism by the police to tell prank calls from real threats.

How does this work? Do you have to hold the line for a few minutes and explain them how the bombs were built? Do you first have to send in your application with a CV to be taken seriously? It’s probably still possible to tell a 12-year old from an adult, but to tell a potential mass murderer from a lazy, chicken terrorist?

Some people said that during the troubles with the IRA in Northern Ireland the IRA had certain codewords to tell the police so they knew the threat was real. But I can’t believe that this is the usual filtering mechanism. First you blow up something/someone, then you send in your application and then you’re given the TANs.

Does anybody know more about this? I mean sometimes the filtering mechanism fails and, for example, the Eiffel Tower is closed (and evacuated). In my understanding they never find any real bomb in these cases but maybe they just don’t want to spread panic and never tell the public.

I certainly have no terrorist energy myself, but I’m just wondering how these things work. Certainly, there are “intelligent” (but sick/crazy) people among terrorists and they must have thought of this before. Maybe they even tried. What stopped them? Why are not all transatlantic flights constantly canceled due to bomb threats?

Help me out and explain the world to me please. Oh, and please use your recognized terrorist codeword so I can be sure you know what you’re talking about.