The POI is multi-system access platform, is a communication device that combines communication signals of different frequency bands into one signal for transmission in a cable (including CDMA800, GSM900, GSM1800, PHS1900, 3G, etc.), and then bring the combined signals into the antenna feeder distribution system to make full use of resources and save the investment. Mainly used for indoor coverage of large buildings, such as stadiums, convention and exhibition centers, exhibition halls, airports, and subways.