Call Detail Records [CDR]
A Telecom Call Detail Record [CDR] or Station Message Detail Recording
[SMDR] is a file containing information about recent system usage.
A Call Detail Record contains at a minimum the following fields:
- Number making the call (A number) - Source ID - points of origin
- Number receiving the call (B number) - Destination ID - endpoints
- Date and Time call was commenced
- Duration of the call
- Amount billed for each call
- Total usage time in the billing period
- Total free time remaining in the billing period
- Running total charged during the billing period.
Other information available:
- Telephone exchange ID writing the record
- Sequence number identifying the record
- Additional digits on the B number used to correctly route or
charge the call
- Result of the call [answered, busy, failed to connect]
- Route the call entered the exchange
- Route the call left the exchange
- Any fault condition encountered
- Any facilities used during the call [call waiting, call diversion
The format of the CDR varies among telecom providers or programs.
A CDR file may contain more than one type of call traffic, with
each type identified separately for rating purposes.
Many Telecom providers supply users with itemized bills, based
on this CDR data.
CDRs are also used to analyse network performance, providing information
on faulty calls and the amount of traffic along particular routes.
IP Detail Record [IPDR]
And IPDR provides data on Internet Protocol (IP)-based service
usage and other activities as required by the Operational Support
Systems [OSS] and Business Support Systems [BSS].
The content varies based on the service and the network. The envelope
carrying the content must meet packaging, encoding and transport
protocols specified by the Internet Protocol Detail Record Organization,
Inc. [IPDR.org]. IPDR.org aims to standardize usage information
exchange between network and OSS/BSS systems. More on IPDR
While CDR and SMDR are similar, they are used by different groups,
for different purposes:
- CDR - used by Telco to create bill, charge
for interconnect and roaming and manage the network performance.
- SMDR - used by an end user organization to
better understand their telephone usage and billing.
Generation of CDRs
CDRs are generated by Automatic Message Accounting [AMA] and processed
by the Operations Support System [OSS].
Operations Support System [OSS]
An operational support system [OSS] is a set of programs used by
a telecommunications service provider to monitor, control, analyze
and manage a telephone or computer network.
With the complexities of merging call records of traditional voice
telephone with packet-oriented Internet traffic [including VoIP],
broadband applications such as teleconferencing and DSL, a more
sophisticated systems was required to manage associated services
- Ordering and tracking network components [including IP addresses]
- Usage and traffic patterns
Tier 1 carriers generate billions of call detail records every
day. With increasing pressure to complying with law enforcement
to investigate call pattern analysis and manage revenue assurance,
as well as standard operations such as better understanding network
call routing patterns,
Call Accounting System
Telcos need powerful and sophisticated architecture to manage,
store and analyse CDR's. CDRs are produced by the charging system
of the telephone exchange. This is refered to as the Call Accounting
System or Billing support system [BSS]. The billing system calculates
the price of the call from the data in the CDR.
A Call Accounting System will collect, track and store data from
calls of all types :
- On-net, or internal calls which are routed from an extension
on one switch to an extension on another switch.
- On-net to off-net calls which are routed from an extension
on one switch through another switch, and off to the public network.
- Off-net to on-net calls which are routed from the inbound trunk
of one switch to an extension on another switch.
- All call records for each hop are stored as separate entries
in the database.
- All call records that represent a single call sequence are
linked together. Each call is assigned up to two monetary values;
the cost and the chargeback amounts.
- Bill reconciliation reports present only one call for every
call leaving or entering the network, showing the exact cost of
- Traffic Reports present all legs.
- Chargeback reports present only the final leg, showing the
chargeback amount. Note that the charge back amount may be equal
to the cost or set to some different value. Also, on chargeback
reports a call may have more than one final leg, such as in the
case of call transfers/conference.
More on call accounting systems.
Communication Management Software
A system is also needed to transport the CDRs via computer networks
to a central point for processing. This is known as Communication
Next: IP Data Records [IPDR]
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