Various law enforcement agencies, including the FBI's bomb data center, provide a formula for responding to such a threat. The one from the FBI is actually on card stock and is small enough that you can keep it right with you near your phone. It contains the essential questions you need to ask if you get a threatening call.

There needs to be a calmness and a matter-of-fact quality to a well-managed call. There's no point in . There are certain things you are trying to get from the caller. But I can tell you that in well over 98 percent of all bomb threats, there isn't any conversation at all. It's a one-sentence conversation. The caller says, "There's a bomb in your building." That's it.

We train people to ask questions like, "Where is the device in the building? When is it going to go off? Why are you doing this?" The most important thing to find out is when. The second most important thing to know is where. The third is what it looks like.

Obviously if you can get all the way to "Why are you doing this?," it's a signal that it is indeed a genuine threat. If the guy is on the phone with you that long and is willing give that much information, there is a high chance it is real. Specificity is a defining feature of a valid threat.

What are the motivations for someone to make a bomb-threat call? The first is an overwhelming desire to cause destruction, panic, concern and anxiety. If a person is calling and there is a device, it could be that the bomber wants to cause terrific property damage but doesn't want to hurt anybody. In fact, that's the reason a great number of actual bomb incidents occur during non-business hours. You'd be surprised how often that is the case. They want to strike out against the organization, but they don't want to be guilty of murder.