ring and maintenance of the resources. This includes detecting faults in the resources and resolving the issues. Collecting usage records from the network and ensuring better utilization of the infrastructure is a part of monitoring. Security of the infrastructure and fraud detection is also an activity that is performed by the support systems. The services should be offered on a secure and reliable infrastructure. 19.5 Defining OSS and BSS On a broad level, OSS is expected to mean any type of support system related to operations in service provider space. In current management space, the scope of OSS is more limited. OSS can be divided into three types of management solu- tions. They are: 1. BSS (business support systems): These are solutions that handle business operations. It is more customer-centric and a key part of running the busi- ness rather than the service or network. Some of the high level functions in BSS include billing, CRM (customer relationship management), marketing support, partner management, sales support, and SO forth. These high level Fundamentals of EMS, NMS and OSS/BSS functions encompass several functions each of which can be a specialized solution. For example, billing will have activities like invoicing, payment pro- cessing, discounts and adjustments, account management, and credit man- agement. Similarly, CRM will have activities like order management, trouble ticket management, contract management, and SLA breach management. 2. OSS (operation support systems): These are solutions that handle service management. It includes functions like service assurance, manage services reporting, and SO on. In most discussions where OSS is mentioned, it is the service management that is the key focus and not any type of support sys- items. So OSS can be used in the context of any type of support system or to specifically mean service oriented solutions. It is also referred to as "service OSS" to avoid the ambiguity in usage of OSS as the holistic support system. 3. NMS (network management system)