From 8421ee160b2e193149236fc6df0cc6f3d5b275ba Mon Sep 17 00:00:00 2001
From: Stephen Smith <stephen@vapi.ai>
Date: Thu, 16 Jul 2026 19:51:30 -0700
Subject: [PATCH] Added Vapi voices as multilingual

---
 fern/customization/multilingual.mdx  |  1 +
 fern/providers/voice/vapi-voices.mdx | 39 ++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/fern/customization/multilingual.mdx b/fern/customization/multilingual.mdx
index 94c3686c9..1be7a6efb 100644
--- a/fern/customization/multilingual.mdx
+++ b/fern/customization/multilingual.mdx
@@ -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 |
diff --git a/fern/providers/voice/vapi-voices.mdx b/fern/providers/voice/vapi-voices.mdx
index 028d8d2c7..f0fb449d5 100644
--- a/fern/providers/voice/vapi-voices.mdx
+++ b/fern/providers/voice/vapi-voices.mdx
@@ -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.