Details : Cell phone becomes especially helpful when people get into critical situations. In case of emergency a timely call can save somebody’s life. Unfortunately, there are still some places where they can find themselves “out of coverage” No signal at all. Usually those places either too far from the cell phone ,base station or located inside underground constructions, for example: Parking lots, tunnels, big stores, office buildings, cars, boats etc. House in remote areas, office area, factory, hospital, warehouse, home.how does it works : The outside antenna catches low signal from operator servicer’s base station and delivers it to cell phone repeater through the connection cable (coax). After the signal is accepted by the mobile repeater, this device amplifies it. And after that, the amplified signal transmits to your cell phone. Then this amplified signal goes through the connection cable (coax) to the inside antenna. Finally, your cell phone will get good signal, never on and off.