Vapi is the Voice AI platform for developers.

Vapi AI

I’m trying to update an assistant to use a custom Inworld voice, but Vapi returns 400 Bad Request

Assistant ID:
13fcc1ad-858e-4582-a68b-ba684dfe46a6

Inworld confirms the voice exists.

Payload sent:

{
  "voice": {
    "provider": "inworld",
    "voiceId": "voiceidstring",
    "model": "inworld-tts-1.5-max"
  }
}

I also tried adding "languageCode": "en", but it still returned 400.

Built-in Inworld voices like Alex work in the same Vapi account, so this seems specific to custom Inworld voice IDs.

Can you confirm the correct payload, or check if custom Inworld voice IDs are currently being rejected?

Hey! I've worked with Vapi and custom voice integrations before  this looks like it could be a validation issue on Vapi's end with how custom Inworld voice IDs are handled vs. their built-in ones.

A couple of quick things to check:
- Make sure the voiceId matches exactly what Inworld's API returns (case-sensitive)
- Try omitting the `model` field to see if that's triggering the 400

If you're still stuck, feel free to DM me  happy to jump in and debug this with you! 

<@727511859728744449>