In managing VoIP-based communication systems, especially with ISSABEL or Asterisk, understanding the structure of system-generated files can greatly streamline operations and troubleshooting. One area often overlooked is the naming convention of call recording files.

Consider the following filename:

force-0821XXXX8663-3201-20250327-092517-1743042317.12206.wav

At a glance, this might appear as a random string, but it encapsulates critical metadata that reflects when, where, and with whom the call took place. Let’s explore this format in detail.

Detailed Breakdown of the Filename Components

1. force
   This typically refers to the recording context or dialplan identifier. It could represent:
   • A specific campaign (e.g., outbound sales, support).
   • A dialplan context defined in extensions.conf or extensions_custom.conf.
   • A custom prefix assigned through recording scripts.
   Administrators can customize this via Asterisk’s dialplan using variables like ${MIXMON_CALLERID}, ${MIXMON_DIR}, or manually appended identifiers.
2. 0821XXXX8663
   This is the external phone number involved in the call, often masked for privacy. Depending on configuration:
   • It could represent the caller ID (from PSTN/SIP).
   • Or the dialed number if outbound.
   For custom setups, this value may be dynamically assigned using channel variables such as ${CALLERID(num)}.
3. 3201
   The internal extension—usually the SIP or IAX2 user within the ISSABEL system handling the call. Mapped from:
   • The device or endpoint that initiated or received the call.
   • Useful for tracking agent performance or routing logic.
4. 20250327
   The call date, formatted as YYYYMMDD for easy sorting and retrieval. This format is often configured in recording scripts or dialplan logic.
5. 092517
   The call start time, in HHMMSS format.
   • Precise to the second, allowing unique file generation even for high-volume call environments.
6. 1743042317.12206
   A combination of:
   • UNIX timestamp (seconds since epoch): 1743042317 → allows precise timing reference.
   • Asterisk’s unique call identifier: 12206 → derived from internal CDR or channel tracking.
   This ensures that even if multiple calls occur simultaneously with the same parties, each recording remains uniquely identifiable.
7. .wav
   The audio file format used for storing the recording. While .wav offers superior audio quality:
   • You can switch to .gsm, .mp3, or .ulaw by modifying the mixmonitor settings for better storage efficiency.
   • Example: Set(MONITOR_FORMAT=mp3) in the dialplan.

Advanced Use Cases & Customization

• Custom Filename Variables
  Modify filename logic in the dialplan using: Set(MONITOR_FILENAME=${CALLERID(num)}-${EXTEN}-${STRFTIME(${EPOCH},,%Y%m%d-%H%M%S)})
• Automated Archiving
  Integrate with cron or systemd services to:
  • Move recordings to external storage.
  • Compress old recordings periodically.
  • Encrypt recordings using GPG or AES before archiving.
• Integration with CRMs or BI Tools
  Parse filename components to:
  • Populate call logs in CRM.
  • Generate performance reports (per agent, per campaign).
  • Link recordings directly to customer profiles.

Security Considerations

1. Access Control
   Ensure directory-level permissions are enforced: chown asterisk:asterisk /var/spool/asterisk/monitor chmod 750 /var/spool/asterisk/monitor
2. Encryption at Rest
   Use file-system level encryption (e.g., LUKS) or encrypt individual recordings.
3. Data Retention Policies
   Implement automated deletion for recordings older than a set threshold (e.g., 30/90 days), aligned with privacy regulations.
4. Audit Trails
   Log every access to recording files using tools like auditd or fail2ban for unauthorized attempts.

Closing Perspective

The humble recording filename, often overlooked, holds significant value for operational efficiency, compliance, and data integrity. By decoding its structure, VoIP administrators can:

• Rapidly locate specific call recordings.
• Automate workflows tied to call data.
• Strengthen data privacy practices.