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Added Vapi voices as multilingual #1106

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stephenvapiai merged 1 commit into from
Jul 17, 2026
Merged

Added Vapi voices as multilingual #1106

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1 change: 1 addition & 0 deletions fern/customization/multilingual.mdx
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Expand Up @@ -471,6 +471,7 @@ Validate your configuration with different languages and scenarios.

| Provider | Languages | Multilingual Voice Selection | Best For |
|----------|-----------|------------------------------|----------|
| **Vapi** | 40+ | ✅ Automatic | Curated voices with built-in language detection |
| **Azure** | 140+ | ✅ Automatic | Maximum language coverage |
| **ElevenLabs** | 30+ | ✅ Automatic | Premium voice quality |
| **OpenAI TTS** | 50+ | ✅ Automatic | Consistent quality across languages |
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39 changes: 39 additions & 0 deletions fern/providers/voice/vapi-voices.mdx
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Expand Up @@ -37,6 +37,45 @@ To use V2, set `version: 2` on your voice configuration through the API or in th
}
```

## Language and multilingual support

Vapi Voices aren't limited to English. The accent listed for each voice (for example, Canadian or Indian American) describes the voice's character — not the only language it can speak. Any Vapi Voice can speak a range of languages, set through the `language` field on your voice configuration.

How multilingual works depends on the voice **version**:

- **Version 2** supports 40+ languages and defaults to **automatic language detection**. Leave `language` unset (or set it to `auto`) and the voice detects and speaks the language of the conversation. You can also pin a single language (for example, `es`).
- **Version 1** supports 30+ languages, including English, Spanish, French, German, Italian, Portuguese, Hindi, Japanese, Korean, Chinese, Arabic, and Russian. Set `language` to the code for the language you want (for example, `es-ES` or `hi`).

```json
{
"voice": {
"provider": "vapi",
"voiceId": "Elliot",
"version": 2,
"language": "auto"
}
}
```

To always speak one specific language instead of auto-detecting, set `language` to that language's code:

```json
{
"voice": {
"provider": "vapi",
"voiceId": "Savannah",
"version": 2,
"language": "es"
}
}
```

For the full set of accepted language codes, see the `voice.language` field in the [Create Assistant API reference](/api-reference/assistants/create).

<Tip>
For a fully multilingual assistant, pair the voice with a transcriber that supports automatic language detection and list the supported languages in your system prompt. See [Multilingual support](/customization/multilingual) for the end-to-end setup.
</Tip>

## Active Voices

These voices are fully supported and recommended for new assistants. The voices below marked <span style={{color: '#3b82f6', fontWeight: 'bold', fontSize: '0.75em', verticalAlign: 'super'}}>V2</span> support the upgraded version 2 model.
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