> ## 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.

# Model Config

> Model configuration options for the Telnyx Speech-to-Text REST API — biasing, hotwords, language hints, and per-request tuning of transcription accuracy.

<Info>
  Deepgram only. Returns 400 if used with other models.
</Info>

Pass-through to [Deepgram's pre-recorded API](https://developers.deepgram.com/docs/pre-recorded-audio) query parameters. Every key-value pair in `model_config` is forwarded directly — Telnyx does not validate individual options.

## Commonly Used Options

| Option         | Type    | Description                                                               |
| -------------- | ------- | ------------------------------------------------------------------------- |
| `smart_format` | boolean | Capitalization, punctuation, dates, numbers, currency                     |
| `punctuate`    | boolean | Add punctuation                                                           |
| `diarize`      | boolean | Speaker identification. Adds `speakers` array to `verbose_json` segments. |
| `utterance`    | boolean | Segment transcript into utterances                                        |
| `numerals`     | boolean | Convert spoken numbers to digits                                          |
| `language`     | string  | Override language. Top-level `language` param takes precedence.           |

## Example

```bash theme={null}
curl -X POST https://api.telnyx.com/v2/ai/audio/transcriptions \
  -H "Authorization: Bearer $TELNYX_API_KEY" \
  -F "file=@call-recording.mp3" \
  -F "model=deepgram/nova-3" \
  -F "response_format=verbose_json" \
  -F 'model_config={"smart_format": true, "diarize": true, "punctuate": true}'
```

`model_config` can be sent as a JSON string in the multipart form field. The server parses it before forwarding.

## Unvalidated Pass-Through

Any Deepgram query parameter can be passed. If Deepgram adds new options, they work immediately without a Telnyx API update. Conversely, invalid keys are forwarded and may cause Deepgram to return an error.

Refer to [Deepgram's API reference](https://developers.deepgram.com/reference/listen-file) for the full list of supported parameters.