Abstract: A portable intrusion detection, monitoring and alarm system is housed in a portable carrying case in the configuration of a briefcase with handle for convenient portability and inconspicuous placement at a desired location near a space to be monitored. Intrusion detectors are removed from the carrying case and placed in the space to be monitored. The intrusion detectors may include infrared motion sensors and radio transmitters for transmitting detection signals to a radio receiver in the carrying case. An electronic controller receives the detection signals from the radio receiver and delivers actuating data signals to a digital communicator and digital dialer with a telephone line output. The digital communicator captures a telephone line with dialing signals and sends further coded signals corresponding to different monitored spaces and intrusion detectors from which detection signals are received.