1.It can be used in any space where GSM network covers flexibly and conveniently. 2.Effective means on improving the utilization ratio of GSM network. 3.offering high-quality convenient telephone service for user. 4.developing the service for public mobile communication network firms. 5.GSM PBX adopts module design .One unit takes 4 or 8 users of inner line as an exterior line interface. It can carry on different grade-links according to demands of user. The most grade-links reach 4, namely 4 GSM exterior line interfaces and 32 inner line ports. 6.Support Inner line Communicating, exterior line Communicating and call conference 7.Support call waiting, call transfer, call intercepting and request connecting. 8.Connect the computer through the standard USB port, monitoring the system; 9.Charge for each port of inner line 10.Connect the printer through RS-232 port, print the simple call bills.