> ## Documentation Index
> Fetch the complete documentation index at: https://developers.telnyx.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Language

> Configure the language for Telnyx Speech-to-Text WebSocket streaming using BCP-47 codes, with per-engine differences in supported languages and behavior.

BCP-47 language code. Default: `en-US`.

```
wss://api.telnyx.com/v2/speech-to-text/transcription?language=es
```

## Auto-Detection

Pass `multi` to enable automatic language detection. The aliases `auto` and `auto_detect` are silently mapped to `multi`.

```
?language=multi
?language=auto        # → multi
?language=auto_detect # → multi
```

## Engine Support

| Engine       | Behavior                                                                                                                                                               |
| ------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Deepgram     | BCP-47 codes. `multi` for multi-language mode.                                                                                                                         |
| Telnyx       | Whisper-based. `auto_detect` disables language hint entirely.                                                                                                          |
| Google       | BCP-47 codes.                                                                                                                                                          |
| Azure        | BCP-47 codes.                                                                                                                                                          |
| xAI          | Language codes such as `en`, `fr`, `de`, and `ja`.                                                                                                                     |
| AssemblyAI   | Automatic multilingual detection and code switching across supported languages.                                                                                        |
| Speechmatics | Language codes such as `en`, `es`. Bilingual packs use Telnyx shorthand (e.g. `ar_en`) — mapped internally. Does not support `auto`; defaults to `en` if unrecognized. |
| Soniox       | Automatic language detection. The `language` parameter is ignored — Soniox detects the language from the audio stream.                                                 |

## Supported Languages

For most engines, Telnyx passes the language code directly without validation. The supported set depends on which engine you use. Speechmatics is the exception — Telnyx accepts shorthand codes for bilingual/multilingual packs and maps them to the provider's `language` + `domain` configuration internally.

| Engine       | Languages                                                                                                                                                                                                                                                                                    | Reference                                                                                                              |
| ------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- |
| Deepgram     | 40+ languages across Deepgram models. Nova-3 supports `multi` (10 languages in code-switching mode). Flux supports English, Spanish, French, German, Hindi, Russian, Portuguese, Japanese, Italian, and Dutch.                                                                               | [Deepgram languages](https://developers.deepgram.com/docs/models-languages-overview)                                   |
| Telnyx       | Whisper-based. 50+ languages. `auto_detect` to skip language hint.                                                                                                                                                                                                                           | —                                                                                                                      |
| Google       | 125+ languages/locales.                                                                                                                                                                                                                                                                      | [Google Cloud STT languages](https://cloud.google.com/speech-to-text/docs/speech-to-text-supported-languages)          |
| Azure        | 100+ languages/locales.                                                                                                                                                                                                                                                                      | [Azure Speech languages](https://learn.microsoft.com/en-us/azure/ai-services/speech-service/language-support?tabs=stt) |
| xAI          | 25 languages, including Arabic, English, French, German, Hindi, Japanese, Korean, Portuguese, Spanish, and Vietnamese.                                                                                                                                                                       | [xAI Voice API](https://docs.x.ai/developers/rest-api-reference/inference/voice)                                       |
| AssemblyAI   | 6 languages with native multilingual code switching: English, Spanish, German, French, Portuguese, and Italian.                                                                                                                                                                              | [AssemblyAI supported languages](https://www.assemblyai.com/docs/streaming/universal-3-pro/supported-languages)        |
| Speechmatics | 17+ languages. Standard codes (`en`, `es`, `cy`, `sw`, etc.) plus Telnyx shorthand for bilingual/multilingual packs (`ar_en`, `cmn_en`, `en_ms`, `en_ta`, `cmn_en_ms_ta`). Telnyx maps these internally to Speechmatics `language` + `domain` params — do not pass them raw to the provider. | [Speechmatics languages](https://docs.speechmatics.com/introduction/supported-languages)                               |
| Soniox       | Automatic language detection — no language hint required. The `language` parameter is ignored.                                                                                                                                                                                               | [Soniox docs](https://soniox.com/docs)                                                                                 |

## Common Codes

| Code            | Language                                |
| --------------- | --------------------------------------- |
| `en` or `en-US` | English (US)                            |
| `en-GB`         | English (UK)                            |
| `es`            | Spanish                                 |
| `fr`            | French                                  |
| `de`            | German                                  |
| `pt-BR`         | Portuguese (Brazil)                     |
| `it`            | Italian                                 |
| `ja`            | Japanese                                |
| `zh`            | Chinese (Mandarin)                      |
| `hi`            | Hindi                                   |
| `ar`            | Arabic                                  |
| `ko`            | Korean                                  |
| `multi`         | Multi-language / auto-detect (Deepgram) |