A charging data record (CDR) is a structured data entity generated by telecommunications network elements that documents the consumption of a chargeable service by a subscriber. CDRs serve as the fundamental source of information for the rating, billing, and settlement processes in telecommunication operators, enabling the calculation of fees for voice calls, messaging, data sessions, multimedia services, and value‑added offerings.
Key characteristics
| Attribute | Description |
|---|---|
| Originating elements | Mobile switching centers (MSC), Gateway GPRS Support Nodes (GGSN), Packet Data Network Gateways (PGW), Service Switching Points (SSP), and other network nodes that deliver billable services. |
| Content | Typically includes subscriber identifier (e.g., IMSI, MSISDN), timestamp, duration, service type, quantity of resources used (e.g., bytes transferred), charging group, rating group, and cause of termination. |
| Record types | Event‑based CDRs (e.g., call setup, call release) and usage‑based CDRs (e.g., volume of data transferred). Some standards also define incremental CDRs for real‑time charging. |
| Processing | CDRs are transmitted to a charging system, which may be an Online Charging System (OCS) for real‑time balance management or an Offline Charging System for post‑hoc rating and invoicing. |
| Standards | Defined by 3GPP specifications such as TS 32.251 (Charging Architecture and Principles) and TS 32.240 (Charging Data Record Formats). ETSI, the Open Mobile Alliance (OMA), and ITU‑T also provide related guidelines. |
| Formats | Represented in ASN.1, XML, CSV, or proprietary binary structures, often employing compression for bulk transport. |
Historical development
The concept of charging data records evolved from early telephony billing, where call detail records (CDRs) captured voice call information. With the advent of mobile and packet‑switched services in the 1990s, network functions were extended to record data usage, leading to the broader notion of charging data records that encompass a variety of service types beyond voice. Standardization efforts by the 3rd Generation Partnership Project (3GPP) in the early 2000s formalized the format and processing architecture, facilitating interoperability across equipment vendors and service providers.
Operational context
- Generation – When a service is initiated, the relevant network element creates a provisional record; upon termination, the record is finalized with actual usage metrics.
- Transport – Records are conveyed via protocols such as GTP‑C (for GPRS/UMTS), Diameter (for LTE/5G), or legacy MAP.
- Rating – The charging system applies tariff rules, converting raw usage into monetary amounts or balance adjustments.
- Billing – Rated CDRs are aggregated into invoices or real‑time balance updates for prepaid subscribers.
- Analysis – Operators may mine CDRs for fraud detection, network optimization, and marketing insights.
Regulatory and privacy considerations
Charging data records contain personally identifiable information and usage details, making them subject to data protection regulations such as the European Union’s General Data Protection Regulation (GDPR), the United States’ CPNI (Customer Proprietary Network Information) rules, and similar statutes worldwide. Operators are required to secure CDR storage, limit access, and retain records only for legally mandated periods.
Related concepts
- Call Detail Record (CDR) – The predecessor term focused primarily on voice call metadata.
- Rating Engine – Software component that applies tariff plans to CDRs.
- Online Charging System (OCS) – Real‑time platform that evaluates CDRs during service delivery to enforce credit limits.
- Offline Charging System (OFCS) – Batch‑processing system that rates CDRs after service completion.
References
- 3GPP TS 32.251, “Charging Architecture and Principles,” Release 17, 2022.
- 3GPP TS 32.240, “Charging Data Record (CDR) Formats,” Release 17, 2022.
- ETSI TS 102 226, “Charging Rules Function (CRF) – Functional and Architectural Overview,” 2017.
- ITU‑T Recommendation Q.1516, “Security and charging for IP multimedia services,” 2002.
The information presented reflects established technical definitions and standards as of the knowledge cutoff date.