The term Operational Support System (OSS) generally refers to the system (or systems) that perform management, inventory, engineering, planning, and repair functions for communications service providers and their networks. A reference model for the interconnection of different types of OSS components and network elements was introduced by the International Telecommunication Union (ITU-T) under the banner of Telecommunication Management Network (TMN).
Since the OSS is mainly concerned with network-related issues, the term Business Support System (BSS) has been introduced to identify customer-oriented processes. BSS typically refers to systems used in dealing with customers, such as taking orders, managing customer data, processing bills and collecting payments.