andle multiple records in parallel to ensure that maximum processing is performed to sup- port real-time billing. Rich information records: The information content in the records is quite huge compared to the actual billable usage information. The additional information is mainly for debugging and validation purposes. The media- tion systems should filter out relevant data based on predefined rules. When new record formats are introduced, the filtering logic needs to be updated to ensure that these records are not omitted as error records. The validation, filtering, and formatting logic is usually implemented to work together to ensure that there are minimum iterations performed on the records there by increasing performance and decreasing processing time. Enormous CDR flow: One of the biggest challenges in designing media- tion systems is to make it scalable enough to handle enormous CDR flows. There are a large number of call or usage records that are pumped to the mediation systems at any given point of time. The mediation systems should OSS/BSS Functions have a mechanism to collect all the records and process them in the shortest possible time. Data correlation: The correlation between records to send consolidation information is also a challenging activity considering the wide variety of ser- vices being offered and the network infrastructure deployed by the service providers in current telecom industry. There are several billing systems that take feed from the mediation system as depicted in the figure on mediation data usage. Data from the mediation systems is used to compute the network usage charges, interconnect charges, roaming charges, and other value added service charges. The data is also achieved in a stor- age system for future reference or for processing by business support solutions like planning, which try to identify usage statistics based on aggregated information in historical records. Next we will discuss the rating engine whose role it is to apply pricing rules to a given transaction, and 