http://www.washingtonpost.com/wp-dyn/content/article/2005/12/09/AR2005120902039.html
During Katrina, virtually every system failed: Internet communications,
radio transmissions, cell phones, even backup gear such as satellite
phones handed out by federal relief workers after the storm. Even when the
equipment worked, officials from different agencies and jurisdictions
could not talk with one another. Their radios were simply not compatible.