ge tracking and archiving, and for managing revenue assurance. A mediation application can also identify and attempt to reconcile events without associated customers (known as unbillable usage), as well as detect Chapter 2 - A Detailed Look at OSS gaps within the usage stream that may indicate a problem with the switch data. Some IICs have implemented mediation systems that collect data from Signalling System Seven (SS7) networks. These packet networks control call set-up and management for many circuit switched networks. The messages they use to signal back and forth carry complete information about the parties, services, and time involved in any session on the network, thus providing a rich source of data for billing and customer analysis. Most mediation systems collect data from switches and access equipment and are thus limited by what data a network element is designed to provide. This isn't generally a major problem other than when dealing with older elements that provide only basic data. Further, only large providers generally have access to, or maintain, SS7 networks, and the technology only applies to circuit networks. SS7 doesn't have much of a role in the data world. A trend for mediation systems is to perform pre-rating functions, delivering usage data to the billing system with some pricing components already computed. Pre-rating is especially important in a real-time billing environment because it not only relieves some of the processing burden from the billing system's rating engine, but puts data in a format ready for delivery to other applications, such as online usage analysis tools. The rating engine itself is a billing system's intelligent component. Receiving data from the mediation system, the rating engine associates usage and other billing parameters to established rating tables that contain information on how much a customer should be billed for any given service. A rating engine worth its salt is highly configurable, allowing for rapid re- pricing of services and re-organization of disco