> ## 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.

# Response Format

> Response format reference for the Telnyx Speech-to-Text REST API — transcript text, words, timestamps, confidence, and per-channel diarization fields.

Controlled by the `response_format` parameter.

## `json` (Default)

Text only.

```json theme={null}
{
  "text": "The quick brown fox jumps over the lazy dog."
}
```

## `verbose_json`

Adds `duration` (seconds) and timestamped `segments` — **only when using `deepgram/nova-3`**. The Whisper models (`openai/whisper-large-v3-turbo`, `openai/whisper-tiny`) return text only regardless of `response_format`. See the [Timestamp Availability](#timestamp-availability-by-model) table below.

Example response with `model=deepgram/nova-3`:

```json theme={null}
{
  "text": "The quick brown fox jumps over the lazy dog.",
  "duration": 3.42,
  "segments": [
    {
      "id": 0,
      "text": "The quick brown fox jumps over the lazy dog.",
      "start": 0.0,
      "end": 3.42
    }
  ]
}
```

Set `timestamp_granularities[]=segment` alongside `response_format=verbose_json`. Using `timestamp_granularities` without `verbose_json` returns 400.

## Segment Fields

| Field      | Type    | Description                                                                    |
| ---------- | ------- | ------------------------------------------------------------------------------ |
| `id`       | integer | Zero-indexed segment number                                                    |
| `text`     | string  | Segment transcript                                                             |
| `start`    | float   | Start time in seconds                                                          |
| `end`      | float   | End time in seconds                                                            |
| `words`    | array   | Word-level timestamps (present when the backend provides them — Deepgram only) |
| `speakers` | array   | Speaker labels (present when `diarize=true` in `model_config` — Deepgram only) |

## Timestamp Availability by Model

| Model                           | `verbose_json` timestamps                           |
| ------------------------------- | --------------------------------------------------- |
| `openai/whisper-large-v3-turbo` | **No timestamps** — backend returns text only       |
| `openai/whisper-tiny`           | **No timestamps** — backend returns text only       |
| `deepgram/nova-3`               | Segment-level + word-level (from Deepgram response) |

## Streaming Response (Undocumented)

Sending `Accept: application/stream+json` returns newline-delimited JSON chunks as segments are transcribed. Each line:

```json theme={null}
{"text": "segment text", "start": 0.0, "end": 3.42}
```

This is used internally but not in the public OAS spec.