Providing 900 and 1800 GSM connectivity, Simple to install/easy to maintain, Allow PIN code entering and reciprocal phone-card lock, Provide optimized circuit directly conmnecting the exchange device for extensions, LCD with back screen, Polarity reversal signal for metering, 3.5dBi gain antenna, Compatible to PABX, Suitable for call termination of ISP, Incoming call remindr,time display.