One especially useful part of the system is that Wayne County can alert various jurisdictions quickly and securely when the U.S. Department of Homeland Security raises its security threat rating, so that jurisdictions know to lock doors and add guards to power plants and water supplies, Hammond said. Before, the various jurisdictions were not always sure the change in the threat rating was legitimate.

Similar capabilities will be possible for chemical plants in a coming phase, he said. He estimated that there are 115 such plants in Wayne County outside Detroit and more than 200 in Detroit.

Hammond is also using the system to operate videoconferences with Wayne County's leaders.

Codespear's system is based on a common Internet Protocol infrastructure, with a small radio-interface adapter at each emergency management center or temporary location that is connected to various radios and devices in use, Hammond and Codespear officials said. The adapter is only 1 by 4 by 6 inches in size and costs in the low thousands of dollars, about the cost of a single 800-MHz ruggedized radio that is carried by an emergency responder, said Gregg Rowland, vice president of marketing at Codespear. About 25 adapters are being used in Wayne County.

Birmingham, Mich.-based Codespear also provides a PC-based user interface based on its SmartMSG server that can be connected to the Global Positioning System to locate units responding to an emergency.