to be formatted data that can be directly interpreted. So the aggregation, correlation, and filtering between billing records takes place in the mediation system to send consolidation information to other business modules. Standard interface for interaction: Multiple business modules make use of the information from the mediation system. Hence it is important that the mediation system is not designed for communication for a specific module. The interfaces for data request and response need to be stan- dardized. These standard interfaces are published for business modules to easily interoperate with the mediation system. The function here is a seamless flow of information between the mediation system and business support systems. d. Drop nonbillable usage: All information in a usage record will not be useful for billing. Only specific fields in the raw records collected from the network elements can be utilized for billing. As part of formatting the records, the mediation system will drop nonbillable usage information and the unused fields are filtered. It should be understood that this activ- ity is quite different from rating. In rating some usage may not be billed based on terms in the SLA, but the mediation systems needs to collect and send all billable usage information for rating. Support for real-time applications: Mediation systems have to support real-time application billing. This requires immediate processing of usage records with minimum processing time. The usage records are computed while the service is being used and information of the usage bill has to be generated at the end of each usage session. Abstraction: One of the most important applications of a mediation system with regard to usage data is to insulate the biller from the network elements generating the raw data required for billing. In the absence of a mediation module, the biller will have to work with indi- vidual data coming from each network element to compute the usage data. This abstraction of generating useful information for the b