Introduction: GSM900Mhz/DCS1800MHz/PCS1900Mhz network ,It has higher receive sensitivity and better interference resistance ability ,It can supply customer with credible speech service and other multiplication service in the area of effective network bestrow. And solve the communication problem effectively where cable telephone can't reach in. The telephone is suitable in metro, speedway, ship, mine, power plant ,parking lot, steel plant, big engineer and etc ,which used in the serious environment with special requirement of waterproof, dustproof ,explosive proof ,anti-jamming and so on.