Call Detail Recording

Call detail recording (CDR) is the automatic log a phone system writes for every call it handles. Each CDR captures who called whom, when, how long, and through which route — the metadata layer that fuels billing, quality assurance, workforce planning, and regulatory audits across modern BPO operations.

A CDR is not the audio. It is the transaction record: origin number, destination number, timestamp, duration, disposition code, trunk ID, and often the agent extension. Voice files, if kept, live in a separate recording archive under different retention rules.

Every PBX, softswitch, and cloud contact center platform emits CDRs by default. Outsourcing buyers rely on them to verify vendor SLAs, reconcile invoices, and spot fraud before it compounds into a material loss.

Key takeaways

• CDR is metadata about calls, not the call audio itself.
• Every telephony platform, from legacy PBX to cloud VoIP, generates CDRs continuously.
• Buyers use CDRs to audit BPO invoices, staffing accuracy, and compliance posture.
• Retention windows are dictated by regulation, not IT preference.

How it works

CDRs are written the instant a call clears the switch. Fields vary by vendor, but the core schema has stayed remarkably consistent across on-premise PBXs and cloud VoIP systems since the 1990s. A typical record contains 20 to 40 fields.

The essential ones look like this:

Records stream to a mediation server that normalises formats, then land in a billing database or data warehouse. Analytics tools query that warehouse to feed dashboards on average handle time, occupancy, and abandonment.

Retention is typically 6 to 24 months for operational use, and longer for regulated verticals. PCI DSS section 10.7 requires at least one year of audit-trail retention for cardholder-adjacent logs, per the PCI Security Standards Council, while the EU’s General Data Protection Regulation pushes retention down to the minimum necessary for the documented purpose.

Examples

CDRs sit at the heart of every large call operation. Three concrete uses show what the data actually does day to day inside Philippine and Indian BPO delivery centres in 2025.

Billing reconciliation. Concentrix and Teleperformance, the two largest global BPO providers, run nightly CDR jobs to match carrier invoices against internal traffic. A single missed field can hide six-figure telecom overspend across a 50,000-seat estate.

Workforce staffing. A Manila-based delivery centre feeds CDRs into its Verint or NICE platform each morning. Supervisors see occupancy by half-hour and reforecast the next shift’s schedule the same day, tightening workforce management accuracy.

Regulatory audits. Financial-services campaigns handling US consumers must prove that call disclosures were made. During a 2024 CFPB examination of a debt-collection vendor, CDRs proved which agents dialled which consumers and when — a defence impossible without the log. Similar audit patterns show up in customer service queues, virtual assistant services desks, and outsourced software development support lines.

Related terms

Call detail recording overlaps with several adjacent concepts. Each answers a different operational question, from data structure to data purpose to data protection, so understanding the borders keeps procurement conversations honest and vendor scorecards fair.

• Call center: the facility or team that runs CDR-emitting phone campaigns.
• Contact center: broader than a call centre, covering email, chat, and social channels alongside voice.
• VoIP: the transport layer whose SIP signalling generates most modern CDRs.
• Quality assurance: the review discipline that pairs CDRs with audio scoring.
• Workforce management: the staffing discipline that consumes CDRs as raw input.
• Business process outsourcing: the wider sector that runs CDR-heavy operations end to end.

FAQ

What is the difference between a CDR and a call recording?

A CDR is metadata about the call: who, when, how long, and via what route. A call recording is the audio itself. Systems store them separately, and their retention policies usually differ.

How long should we retain CDRs?

Operational teams typically hold 6 to 24 months. PCI-scoped environments must keep at least one year of audit logs. GDPR-scoped operations should retain only as long as the documented purpose requires.

Are CDRs personal data under GDPR?

Yes. A CDR links a phone number to a call event, which counts as personal data under the General Data Protection Regulation. Treat CDR stores with the same access controls as any customer database.

Do cloud contact centres still produce CDRs?

Every major cloud platform, including Amazon Connect, Genesys Cloud, Five9, and NICE CXone, emits CDRs through APIs or streaming exports. Format varies, but the core fields carry over from the PBX era.

Can a BPO client access the vendor’s CDRs?

Standard master service agreements grant clients read access to CDRs relevant to their campaign. Full-schema access, including cost fields, is usually redacted. Negotiate this in the statement of work, not after go-live.

What frameworks reference CDR retention?

NIST’s Cybersecurity Framework treats call logs as audit records under the Detect function. PCI DSS 10.7 sets minimum retention. Sector-specific rules such as HIPAA and MiFID II add further requirements on top.

Compare CDR-savvy BPO vendors on the Outsource Accelerator hub, or start with the Top 40 BPO companies in the Philippines shortlist before your next telephony contract review.