This handy cell phone detector, pocket-size mobile transmission detector or sniffer can sense the presence of an activated mobile cell phone from a distance of one and-a-half metres. So it can be used to prevent use of mobile phones in examination halls, confidential rooms etc. It is also useful for detecting the use of mobile phone for spying and unauthorized video transmission. Mobile Phone Detector simultaneous detects four bandwidths (GSM, DCS, CDMA and 3G) transmission signal. Each band is designed with individual detection circuit for high sensitivity and consistency. Its broad band log amplifier and active striping filter is designed for high selectivity and low false alarm. It can look through the Mobile phone signal and automatically activate the jamming device to break the communication when needed. Therefore it can eliminate the health concern of always-on jamming radio wave to human body. Also it has the power-line data communication circuit and it uses AC power line to send operational status and receive control signal.