Emergency! When a message has to get through
 

*Source: ComputerWorld (http://www.computerworld.com/action/...tsrc=hm_list)*
__________
September 07, 2007 (Computerworld) (http://www.computerworld.com/) -- Let's say that a major bridge in your city has collapsed at the height of rush hour, claiming an unknown number of victims. You'd like to communicate with your staff, both to ascertain their well-being and to tell them what to do tomorrow.

You could set up a call tree, and have every person call five other people until everyone was reached. Setting up one would be slow, and getting results would be even slower. Worse yet, the first thing that typically happens during local disasters is that the phone system is overwhelmed, making it difficult to reach anyone.

More...