### Answer
The error "pipeline-error-openai-voice-failed" indicates there was an issue with the OpenAI voice integration within your Vapi call. This could be due to various reasons such as issues with the voice service provider or configuration problems. To troubleshoot, you might want to review the assistant's configuration, especially related to voice settings, and ensure all required fields are correctly set up and the voice service is operational. If the issue persists, checking the Vapi documentation or reaching out for support might be necessary. For more detailed insights into call errors, you can refer to the "Get Call" API endpoint documentation [(1)](
) .