Custom Voice Not Triggering Voice Generation Request for First Message
Title:
Custom Voice Not Triggering Voice Generation Request for First MessageIssue Summary:
When using a custom voice configuration, the agent fails to send a voice generation request for the first message, even when
firstMessageMode is explicitly configured.Expected Behavior:
The agent should generate and speak the first message using the configured custom voice according to the settings in
firstMessageMode.Actual Behavior:
No voice generation request is sent for the first message when a custom voice is set, resulting in a silent start to the conversation.
Configuration Attempted:
- Set
firstMessageModeto'assistant-speaks-first' - Set
firstMessageModeto'assistant-speaks-first-with-model-generated-message' - Custom voice configured as per documentation
- Custom TTS setup: https://docs.vapi.ai/customization/custom-voices/custom-tts
- First message configuration: https://docs.vapi.ai/api-reference/calls/create#request.body.assistant.firstMessage
57ce58fb-11f2-4574-a2a2-aed65706db97started at Jun 29 2025 10:48 UTC
Additional Context:
The issue appears to be specific to custom voice configurations, as the behavior may work correctly with default voices. The logs from the test call above should show the missing voice generation request for the first message.
Learn to integrate your own text-to-speech system with VAPI
