What is the reason for the error “call.in-progress.error-sip-outbound-call-failed-to-connect” https://cdn.discordapp.com/attachments/1448186089809510521/1448186090123952150/a746a763-e06f-42d0-9e6a-c711c96177c2.png?ex=69419825&is=694046a5&hm=d25edc138995b4d046f8839c60ad31e2c269bbd27c7fac426634b8cc1e8bc8f2&

The error

call.in-progress.error-sip-outbound-call-failed-to-connect

means your SIP provider failed to establish the outbound call. This is part of recent updates that replaced generic error codes with more specific ones for easier troubleshooting. Actionable step: Check your SIP trunk configuration and provider credentials in Vapi. For example, ensure your setup matches this pattern:

json
{
  "provider": "byo-sip-trunk",
  "gateways": [{ "ip": "your-sip-provider.com" }],
  "outboundAuthenticationPlan": {
    "authUsername": "YOUR_SIP_USERNAME",
    "authPassword": "YOUR_SIP_PASSWORD"
  }
}

Update your error handling to use the new codes and review your SIP provider's connectivity status. For more details, see the [SIP Call Error Handling Updates](https://docs.vapi.ai/changelog/2025/5/31). Sources: - [SIP Call Error Handling Updates](https://docs.vapi.ai/changelog/2025/5/31) - [SIP Trunking](https://docs.vapi.ai/advanced/sip/sip-trunk)

but some calls are placing fine

For intermittent SIP call failures, use the Vapi dashboard to compare Call Logs of successful and failed calls. Actionable step: Go to

Observe > Call Logs

in your [Vapi dashboard](https://dashboard.vapi.ai/), select a failed call, and review the error details and configuration. Then, compare with a successful call to spot differences in payload, authentication, or routing. This targeted comparison often reveals provider or configuration issues causing intermittent failures. For more, see the [Vapi debugging guide](https://docs.vapi.ai/debugging). Source: - [Debugging voice agents](https://docs.vapi.ai/debugging)

Concurrency issue