# Call Detail Records Call detail records are carrier or service records about communications, commonly including endpoints, time, duration, direction, routing, and billing-related fields rather than the conversation's content. Exact schemas vary by provider and era. ## Notebook evidence [[Scanned_20260730-1830]], PDF pages 6–7, connects CDRs, `180 days`, automatic number identification, pen-register concepts, and USA FREEDOM. The fragments probably combine multiple legal and technical sources and should not be forced into one rule without recovering the copied source. ## Boundary A CDR is a business or network record. It is distinct from real-time pen-register collection, content interception, and a later analytical query, even when the resulting graphs overlap. ## Source - [[Scanned_20260730-1830]], PDF pages 6–7.