CDR modules are used to store call detail records in a variety of formats. Popular storage mechanisms include comma-separated value (CSV) files, as well as relational databases such as PostgreSQL. Call detail records typically contain one record per call, and give details such as who made the call, who answered the call, the amount of time spent on the call, and so forth.

For more information on call detail records, see Section 370. Call Detail Records.

Call detail record modules have file names that look like cdr_xxxxx.so, such as cdr_csv.so and cdr_pgsql.so.