 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 biller makes it easier for business support systems to work on the billing information. 2. Validation functions: The mediation system performs multiple validation functions on the usage records. Some of them are: a. Duplicate checks: This involves identifying duplicate records and elimi- nating them to avoid discrepancies in billing the customer. Eliminate unwanted record: Call failure and dropped calls should be dropped as nonbillable records based on validation checks on the col- lected records. Edit error records: Some records might contain errors that make it non- compliant for mediation processing tasks like correlation and aggregation. OSS/BSS Functions In these scenarios the mediation system will perform edits and transla- tions to make the c