> ## 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.

# Voice Clone API parameters

> Models, audio requirements, and async flows for the Voice Clone API.

## Models

Set via `model_id` (body) on `POST /v2/voice_clones/from_upload`, or use `provider` (body) to select Minimax.

| Model                | Provider         | Audio length                | Max file | Sync/Async      | Best for                            |
| -------------------- | ---------------- | --------------------------- | -------- | --------------- | ----------------------------------- |
| **Qwen3TTS**         | Telnyx (default) | 3–15s (auto-trimmed to 10s) | 5 MB     | Sync (201)      | Short, clean samples                |
| **Ultra**            | Telnyx           | Up to 10s                   | 5 MB     | **Async (202)** | Higher quality, more natural        |
| **speech-2.8-turbo** | Minimax          | 10s–5 min                   | 20 MB    | Sync (201)      | Longer recordings, more vocal range |

## Audio Requirements

Body parameter `audio_file` (multipart) on `POST /v2/voice_clones/from_upload`.

|                   | Qwen3TTS                 | Ultra     | Minimax   |
| ----------------- | ------------------------ | --------- | --------- |
| **Audio length**  | 3–15s (5–10s optimal)    | Up to 10s | 10s–5 min |
| **Max file size** | 5 MB                     | 5 MB      | 20 MB     |
| **Formats**       | WAV, MP3, FLAC, OGG, M4A | Same      | Same      |

* **Qwen3TTS:** aim for 5–10 seconds. Longer isn't better — auto-trims to 10s.
* **Minimax:** longer is better. 1–2 minutes of varied speech gives more vocal range.

## The `ref_text` Parameter

Body parameter on `POST /v2/voice_clones/from_upload`. Optional.

A transcript of what's being said in the audio. Improves clone quality by giving the model a text reference to align against.

## Ultra Async Flow

When `model_id` is `"Ultra"`, the API returns **202 Accepted** instead of 201:

```http theme={null}
POST /v2/voice_clones/from_upload → 202 { "data": { "status": "pending" } }
```

Poll until ready:

```http theme={null}
GET /v2/voice_clones/{id} → 200 { "data": { "status": "active" } }
```

See [Responses](/docs/voice/voice-design-lab/clone-voice/responses) for status values and voice ID format. See [Errors](/docs/voice/voice-design-lab/clone-voice/errors) for Minimax error codes.