PURPOSE: To eliminate the need of a path connection on the network side, and to inform the emergency state to the related facilities even in the case of being resource busy by informing the emergency state by using a D-channel of the integrated service digital ISDN network.

CONSTITUTION: A fire sensing part 7 senses generation of a fire by a temperature sensor 11, and a gas leakage detecting part 8 detects leakage of gas by a gas leakage sensor 12. Also, an illegal intruder discovering part 9 discovers an illegal intruder by an infrared-ray sensor 13, and they give a notice to a control part 5, respectively. The control part 5 reads out address information from an accumulating part 6 in accordance with the informed contents of the emergency state, and outputs emergency state generating information. A D- channel packet communication part 4 is connected to the corresponding related facilities such as a police station, a fire department, a gas company, etc., by using a D-channel of an ISDN network, based on the emergency state generating information from the control part 5, and transfers the emergency state generating information. Accordingly on the network side, the path connection becomes unnecessary, and even in the case of being resource busy, the emergency state can be informed in detail.