Billing
CDRAlso known as Call Detail Record, Call Data Record
Definition
A CDR (call detail record) is a structured record that a phone system, softswitch or network element writes for each call attempt. It captures who called whom, when, for how long, over which route, and how the call ended. CDRs are the raw material for billing, quality metrics such as ASR and ACD, fraud detection and troubleshooting.
What a CDR contains
| Field | Example / meaning |
|---|---|
| Calling / called number | Source and destination, often in E.164 format |
| Start, answer, end times | Used to compute ringing time and billable duration |
| Duration / billsec | Total time and billed (answered) seconds |
| Disposition | ANSWERED, BUSY, NO ANSWER, FAILED |
| Cause code | SIP response or Q.850 release cause (16 = normal clearing, 17 = busy) |
| Route / trunk / device | Where the call went, for cost and quality analysis |
| Codec, call ID | Technical details for troubleshooting |
What CDRs are used for
- [Billing](/glossary/telecom-billing): rating each call against a price list and charging the right account.
- Quality metrics: ASR, ACD and PDD per route, site or device.
- Reconciliation: comparing your CDRs with a carrier’s before paying invoices.
- Fraud detection: spotting unusual destinations, volumes or patterns.
- Troubleshooting: finding which trunk or line failed and why.
Many jurisdictions require operators to retain CDRs for set periods and to protect them as personal data.
CDRs in GSMCalls
CDR formats vary: Asterisk writes CSV or database records, carriers often exchange CSV files, and mobile networks use 3GPP charging formats. Normalising them into one schema is usually the first step before billing or analysis.
GSMCalls keeps full CDRs for every site with billable time, disconnect causes and the numbers behind ASR and ACD, with exports for your own systems. See features and pricing.
Frequently asked questions
What is the difference between duration and billsec in a CDR?
Duration covers the whole call including ringing; billsec counts only the answered, billable part.
Do CDRs include call audio?
No. CDRs are metadata about calls. Recordings, where lawful and enabled, are stored separately.
How are CDRs used to detect fraud?
Analytics look for patterns such as unusual destinations, bursts of short calls or traffic outside business hours, and flag them for review.