CDR mediation

CDR mediation

CDR mediation is intermediary process to billing which follows CDR collection. This is necessary to make sure calls are billed to the right entity and based on the right tariffs.
CDR mediation consists of several processing steps. The following illustrates some of the necessary steps to prepare VoIP Call Details Records for billing.


Normalization is an important process that:

1. Cleans up the CDRs generated by switching equipment of unnecessary or inconsistent
information or format the destinations based on a consistent numbering plan.

Caller Id normalization

A SIP caller Id "blue" <sip:999560003@ag-projects.com;user=phone> is formatted to sip:999600003@ag-projects.com which corresponds to a billable entity in Provider database.

Destination normalization

0235468104@gateway.com for calls in the Netherlands might have the first 0 removed and 0031 appended. After normalization the destination becomes 0031235468104@gateway.com. 0031 has a coresponding rate which can be calculated based on a consolidated international destinations table (00 + Country code + Subscriber number)

Disconnection Code normalization

Example: Cisco release codes are stored in hexadecimal values coresponding to Q931 ISDN release codes defined by ITU.


A process by which each call is assigned a price based on a rating table. Rating may apply differently for PSTN related traffic than NGN related traffic.

PSTN Rating could be based on one or more of the following:

  • Time of Day
  • Day of the week
  • Day of the year (holidays)
  • Duration
  • Destination (like country or mobile network code)
  • Application type (audio, video, text)
  • Network traffic

Telephony-wise calls have different tariffs depending on the time of the day (peak and of peak hours). The rating engine should be able to break the call duration into separate durations billied with the corresponding rate. Example of rating which allow a 41 second call to span multiple rating periods (before and after midnight):

ConnectFee: 0.0454
Span: 1
Duration: 11 s
Traffic: 208178 bytes
Appl: Audio
Dest: 31620 Nederland mobiel
Cust: default
Profile: 421 for weekday
Rate: 422 for 19-24h
DurationRate: 0.2040 / 60 s
TrafficRate: 0.0000
ApplRate: 0.0000
Price: 0.0374
Span: 2
Duration: 30 s
Traffic: 208178 bytes
Appl: Audio
Dest: 31620 Nederland mobiel
Cust: default
Profile: 421 for weekday
Rate: 422 for 0-8h
DurationRate: 0.2040 / 60 s
TrafficRate: 0.0000
ApplRate: 0.0000
Price: 0.102

NGN Rating

In Next Generation Networks context, IP calls might have multiple media components like audio and video. A rating engine should be able to distinguish among them and calculate different prices for each combination application/bandwidth utilization.

Multiple time-zones

SIP based traffic may originate from customers located geographically in different zones. The normalization should take into account the time zone of Calling Party (to display the correct start and stop time), the Billing Party (to apply the peak/off-peak tariff of the service provider servicing the Calling Party).


Communication with external systems could be realised in common understood formats.
  • Comma Separated Values (a.k.a CSV format)

The examples have been extracted from CDRTool an NGN ready mediation system.

CDR Mediation Software

Asterisk Billing
Created by: busywiki, Last modification: Mon 10 of Sep, 2012 (17:34 UTC) by vbrad
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