ATM Customer Network Service System (CNSS) is a project for CHT-I to provide CHT ATM network customers with web-based CNM service to online check their network configuration and performance statistics data, which include PVC and Port information. The customers can also modify their contact information and log-in passwords. This paper will first introduce the architecture of the CNSS. The system functions are detailed described in Chapter III while Chapter IV covers the detailed design of this system. In addition to its original design purpose for CHT ATM customers, this CNSS can also provide services to Frame Relay or leased line customers.