Knowledge management in Enterprise Information Systems (EIS) has become one of the hottest research topics in the last few years. Operations Support Systems (OSS) is one kind of EIS, which is becoming increasingly popular in the telecommunications industry. However, the academic research on knowledge management in OSS is sparse. In this paper, a knowledge management system for OSS is proposed in the framework of systems theory. Knowledge, knowledge management, organization and information technology are the four main interactive elements in the knowledge management system. The paper proposes that each subsystem of the OSS is to be equipped with knowledge management capacity, and the knowledge management of the OSS is to be realized through its subsystems. * Customer care: provide an interface to the customers for all issues related to customer order, sales, billing, and problem handling. * Multi-service provision: activate instances of service for particular customers.