A call detail record (CDR) in voice over IP (VoIP) is a file containing information about recent system usage such as the identities of sources (points of origin), the identities of destinations (endpoints), the duration of each call, the amount billed for each call, the total usage time in the billing period, the total free time remaining in the billing period, and the running total charged during the billing period. The format of the CDR varies among VoIP providers or programs. Some programmes allow CDRs to be configured by the user.

A CDR for a particular account can be downloaded at the request of the subscriber who holds that account. If the VoIP provider supplies users with itemised bills, a CDR will show up in each bill, in a format similar to that of an itemised long-distance telephone bill supplied by a conventional telephone company.

In a telephone exchange, a CDR contains information about all the calls passing through the exchange. The CDRs are generated by Automatic Message Accounting (AMA) and processed by the operations support system (OSS).