NethVoice: Monitor concurrent calls in reports and Naas alerting #8251

Description

Add monitoring of the number of concurrent calls handled by NethVoice, making this information available both in the reporting system and as an alerting mechanism for Naas (Nethesis as a Service) deployments.

The goal is to provide visibility into concurrent call usage over time and proactively detect when a system approaches or reaches its configured capacity.

Proposed solution

Evaluate the use of the Asterisk Prometheus module to expose metrics related to active calls and integrate them into the existing NethVoice monitoring and reporting infrastructure.

The implementation should cover the following aspects:

• Concurrent call monitoring: collect the current number of active calls and track its evolution over time.
• Reporting: make concurrent call statistics available in NethVoice reports, including historical trends and peak usage over a selected period.
• Naas alerting: introduce configurable alerts when the number of concurrent calls exceeds a defined threshold, allowing operators to identify potential capacity issues before they affect service availability.
• Metrics collection: investigate the Asterisk Prometheus module as the preferred approach for exposing metrics, avoiding unnecessary custom instrumentation where possible.

Expected behavior

Reports

• Display concurrent call usage over time.
• Show peak concurrent calls within the selected reporting period.
• Provide sufficient historical data to identify usage patterns and capacity requirements.

Naas alerts

• Allow thresholds to be configured according to the relevant system capacity or service limits.
• Trigger an alert when concurrent call usage exceeds the configured threshold.
• Integrate with the existing Naas monitoring and notification mechanisms.
• Avoid excessive notifications through appropriate alert evaluation and recovery conditions.

Technical considerations

• Verify which concurrent-call metrics are exposed by the Asterisk Prometheus module and whether they accurately represent the calls that should count toward NethVoice capacity.
• Determine how metrics will be collected, stored and made available to the reporting system.
• Define the appropriate sampling interval and historical retention requirements.
• Ensure that the monitoring endpoint is secured and accessible only to authorized monitoring components.
• Assess compatibility with the supported NethVoice deployment architectures.

Acceptance criteria

• Concurrent call metrics are collected reliably.
• Reports display concurrent call usage and peak values for a selected period.
• Naas can configure thresholds for concurrent call alerts.
• Alerts are triggered when thresholds are exceeded and cleared when usage returns to acceptable levels.
• Monitoring works across supported NethVoice deployments.
• The solution has an acceptable impact on system performance.

References

• [Asterisk documentation](https://docs.asterisk.org/)
• Investigate the Asterisk Prometheus module as the preferred metrics source.