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Noise suppression enhances call quality by removing background noise from audio streams. Configure this feature at the connection level or individual phone number level to reduce unwanted ambient sounds during calls.

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Configuration scope

Noise suppression can be configured at two levels:
  • Connection level: Applied to all phone numbers associated with the SIP connection. This setting overrides individual number configurations.
  • Number level: Applied to specific phone numbers for granular control.
Connection-level settings take precedence over number-level configurations, simplifying management and ensuring consistent audio quality across all calls.

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Configuration via API

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Configure at connection level

PATCH /v2/ip_connections/ with the noise_suppression object: 
{
  "noise_suppression": {
    "direction": "both"
  }
}

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Configure at number level

PATCH /v2/phone_numbers//voice with the noise_suppression object: 
{
  "noise_suppression": {
    "direction": "inbound"
  }
}

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Direction options

The direction parameter controls which audio streams are processed:
ValueDescriptionUse case
inboundProcesses audio from the PSTN to your systemClean up audio received by your users or applications
outboundProcesses audio from your system to the PSTNReduce background noise from your users or applications
bothProcesses audio in both directionsMaximum call clarity when both sides may have background noise
disabledTurns off noise suppressionPreserve natural ambient sounds when needed

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Codec compatibility

Noise suppression works with standard SIP trunking codecs including:
  • G.711 (μ-law and A-law)
  • G.722
  • Opus

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Performance considerations

  • Each direction (inbound/outbound) is processed and billed independently
  • Processing adds minimal latency (typically < 20ms)
  • Noise suppression is applied in real-time during the call
  • Connection-level configuration provides consistent behavior across all numbers

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Best practices

  1. Use connection-level configuration for consistent audio quality across all phone numbers
  2. Enable bidirectional suppression (both) for optimal results in noisy environments
  3. Test with your specific use case to balance noise reduction with audio naturalness
  4. Monitor call quality metrics to validate the impact on your application