SBC Trunk Management

1. SBC Trunk Metadata

SBC extends the following metadata for each SIP trunk (stored in the sip_trunk.metadata.sbc JSON field):

1.1 Media Control

media_mode details:

Per-dialplan relay_only (0.5+): for EIP/NAT failure modes where the direct media path never works, a dialplan-level switch forces every leg through the SBC relay regardless of SDP negotiation — set it on the affected dialplan instead of flipping every trunk to all.

ICE-lite (0.5+): for strict full-ICE peers (Microsoft Teams Direct Routing and similar), ice_lite = true makes the SBC answer ICE-lite on plain-RTP legs while WebRTC legs keep full ICE.

1.2 Codec Control

{
  "sbc": {
    "codec_allow": ["pcmu", "pcma", "g729"],
    "codec_deny": [],
    "codec_prefer": "pcmu"
  }
}

1.3 CAC (Call Admission Control)

{
  "sbc": {
    "cac_max_calls": 100,
    "cac_max_cps": 20
  }
}

1.4 Recording Policy

{
  "sbc": {
    "recording": {
      "enabled": true,
      "direction": "both"
    }
  }
}

1.5 Header Manipulation Rules

Add, remove, or modify headers on SIP signaling passing through this trunk:

{
  "sbc": {
    "header_rules": [
      { "action": "add", "name": "X-Gateway", "value": "sbc-01" },
      { "action": "set", "name": "P-Asserted-Identity", "value": "${caller}" },
      { "action": "remove", "name": "X-Internal-IP" }
    ]
  }
}

1.6 Source IP Control

{
  "sbc": {
    "source_ips": ["203.0.113.0/24", "198.51.100.10"]
  }
}

2. Batch Configuration

SBC → Trunks → Batch Settings: Select multiple trunks at once to uniformly set media_mode, video_policy, CAC, and other parameters.

3. Health Check

SBC → Trunks → Health Status:

The SBC page displays real-time health status for all trunks, marking DOWN trunks in red.

4. Console Operations

4.1 View Trunk List

SBC → Trunks: Displays all trunks and their SBC metadata summary.

4.2 Edit SBC Configuration

Click the trunk name → modify the JSON configuration → save. Supports direct JSON editing or form-based editing.

4.3 Reload

SBC → Trunks → Reload: Re-reads trunk definitions from configuration files (does not affect SBC metadata in the database).