A charging data record (CDR) is, in 3GPP

3GPP

The 3rd Generation Partnership Project is a collaboration between groups of telecommunications associations, known as the Organizational Partners...

 parlance, a formatted collection of information about a chargeable event.

CDRs are used for user billing: a telecom provider transfers them from time to time in order to send bills to their users. CDRs are sent using the GTP'

GTP'

GTP is an IP based protocol used within GSM and UMTS networks. It can be used with UDP or TCP. GTP' uses the same message structure as GTP , but it is largely a separate protocol...

 or FTP protocol.

Information on chargeable events includes time of call set-up, duration of the call, amount of data transferred, etc. A separate CDR is generated for each party to be charged.

Entries on CDRs use a {category, usage} syntax. Usage units can be bits (e.g. user downloaded a 1MB movie), seconds (e.g. user downloaded 1 minute of a movie), or other units (e.g. user downloaded 1 movie).

CDR types

CDRs can be classified basically on two parameters

• The node at which they're generated: GGSN, SGSN, PGW, SGW, etc.
• The kind of service or activity they're charging : MBMS, Mobility, Location request etc.

As per the specifications the records are classified as follows :

• S-CDR
• SGW-CDR
• PGW-CDR
• M-CDR
• S-SMO-CDR
• LCS-MO-CDR
• LCS-NI-CDR
• S-MB-CDR
• G-MB-CDR
• MBMS-GW-CDR