Asterisk Call Recording: Call Recording (Latest Versions)

Call recording is one of the most important capabilities in any real-world Asterisk deployment.

Businesses rely on recordings for:

• legal compliance and dispute resolution
• agent quality monitoring and training
• customer experience analysis
• AI transcription and sentiment detection
• audit trails for regulated industries

Because recordings may be used as legal evidence, recording design must be technically reliable, securely stored, and operationally consistent.

How Call Recording Works Inside Asterisk

Asterisk records audio at the channel level. When a call is bridged between two parties:

• Asterisk mixes RTP audio streams
• The mixed stream is written to a file
• Recording continues until hangup or manual stop

Recording can be triggered:

• from the dialplan (automatic recording)
• from user action (on-demand recording)
• from queue or IVR configuration
• from AMI/ARI external control

Common Recording File Location

By default, recordings are stored in:

/var/spool/asterisk/monitor/

Subfolders are often organized by:

• date
• queue name
• agent or campaign

Proper folder structure is essential for large call-center deployments.

Automatic Recording Using MixMonitor

The most widely used recording method is the MixMonitor() dialplan application.

exten => _X.,1,NoOp(Start outbound call with recording)

 same => n,Set(RECORD_FILE=/var/spool/asterisk/monitor/${STRFTIME(${EPOCH},,%Y/%m/%d)}/${UNIQUEID}.wav)

 same => n,MixMonitor(${RECORD_FILE},b)

 same => n,Dial(PJSIP/provider-endpoint/${EXTEN},60)
 same => n,Hangup()

Important options:

• b → record only when call is bridged (no ringing noise)
• UNIQUEID → ensures filename uniqueness
• date folders → prevent filesystem overload

Recording Inbound Calls from SIP Provider

[inbound-provider]
exten => _X.,1,NoOp(Inbound call with recording)

 same => n,Set(RECORD_FILE=/var/spool/asterisk/monitor/inbound-${UNIQUEID}.wav)

 same => n,MixMonitor(${RECORD_FILE},b)

 same => n,Goto(ivr-main,s,1)

Recording early in the dialplan ensures the entire customer interaction is captured.

On-Demand Recording Triggered by Agent

Agents may start recording only when needed:

exten => *1,1,NoOp(Manual recording start)
 same => n,MixMonitor(/var/spool/asterisk/monitor/manual-${UNIQUEID}.wav,b)

This approach is common in:

• privacy-sensitive environments
• regulated financial conversations

Recording Formats and Storage Impact

Typical formats:

• WAV → highest compatibility, large size
• WAV49 / GSM → compressed, smaller storage
• MP3 → requires external conversion

Storage planning is critical:

• 1 minute WAV ≈ 1 MB
• Large call centers generate GBs per day

Secure Storage Best Practices

• restrict filesystem permissions
• store recordings outside web root
• encrypt backups
• define retention policy (30/90/180 days)

Recordings often contain sensitive personal data and must be protected accordingly.

Common Real-World Recording Failures

1. Recording File Not Created

• cause → wrong directory permissions
• fix → ensure Asterisk user can write folder

2. Empty or Silent Recording

• cause → RTP one-way audio or NAT issue
• fix → debug RTP flow first

3. Recording Stops Mid-Call

• cause → disk full or process crash
• fix → monitor disk usage and log errors

Integrating Recordings with CRM or AI Systems

Modern deployments rarely leave recordings only on disk.

• upload to CRM after call completion
• trigger speech-to-text transcription
• run sentiment or compliance AI analysis
• link recording to customer history

This transforms recordings from passive storage into actionable business intelligence.

Monitoring Recording Health in Production

Engineers should regularly verify:

• new recordings are being created
• file sizes look normal
• disk space is sufficient
• log errors are absent

Example disk check:

df -h

Legal and Compliance Considerations

Many regions require informing customers before recording.

• play recording consent message in IVR
• store timestamped proof of consent
• follow data-retention laws

Always align recording strategy with local telecom and privacy regulations.

Production Checklist for Reliable Call Recording

• MixMonitor configured correctly
• date-based folder structure
• disk monitoring and log rotation
• secure storage permissions
• CRM/AI integration pipeline
• legal consent announcement in IVR

Key Takeaway

Call recording is not just a feature — it is a foundation for compliance, quality, analytics, and customer trust.

When designed correctly, Asterisk recording becomes a powerful operational intelligence system rather than simple audio storage.