Mediation is the process of collecting and processing usage data from networked devices, usually for billing purposes.
At Mediation there are following tasks performed.
  • Collecting and validating CDR from network elements (Switches / MSC’s)
  • Filtration (non billing CDR’S)
  • Correlation of different input sources CDR’s
  • Aggregation of partial CDRs related to the same call.
  • CDR normalization.
  • Transformation of data as per business logic.
  • Downstream Format mapping ,header and trailer generation
  • Downstream Distribution
Mediation Flow
Function of Mediation system
Whenever a Subscriber / Customer uses communication services (Voice, Call,SMS ,Data transfer etc ) from a Service Provider,Usage Data are generated at the network element.
The usage data is called as Call Detail Record (CDR) in the traditional voice network environment or Internet Protocol Detail Record (IPDR) in the data network environment. Some of the Service Usage Data sources in the network are:

GSM telephony Network Elements
    GSM telephony
    Voice calls – MSC
    SMS traffic – SMSC
    Data traffic – GGSN
    MMS traffic – MMSC
    Roaming CDRs from business partners
    Interconnect CDRs from partners

The CDRs are normally pushed to or pulled from the switches. The switch generates a CDR file. These file contains header or trailer records containing the number of CDRs in a particular file. The files are generated as they reach a specified count or at regular time intervals.
There are various protocol supported namely  FTP, SFTP, FTAM, X.25.SNMP.SFTP provides a secured way of collecting the CDRs as it uses SSL.
Once CDR file received mediation software pre process  the CDR, This process involves removal of header and trailer , adding extra filed in CDR to process and finally parsed to check with switch format to validate CDR.
Some mediation software collect CDR from network element at physical path then process it, while some collect the same in buffer and after process , one final CDR is sent for further process and one file sent to Archive directory.
A typical mediation workflow: