Key customer management & service sub-system is the first sub-system we developed. It focuses on the remote reading, alarming of abnormal consumption, better customer service and load control & management. The terminal unit of key customer system is designed according to the national standard and clients' requirements. With the application of advanced GSM/GPRS networks communication technology and 32 RISC CPU, compared with the traditional load management terminal unit, it is characterized with wide cover, stable operation, practical, powerful functions. It can be customized to choice the GSM or GPRS.