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

# Send voice notes to a phone number or group

> The Arnio API lets you send Apple voice notes to iMessage recipients or groups. Voice notes are sent as a .caf (Core Audio File) through the media_url parameter. Recipients will see a fully playable inline voice note in their iMessage thread—just like the ones recorded directly in the Messages app.

### Usage

To send a voice note with Arnio:

1. Upload the .caf file to a public storage bucket so Arnio can fetch it.
2. Make sure the file format is .caf (Core Audio File), as this is the only format Apple supports for inline iMessage voice notes.
3. Pass the file’s public URL as the media\_url in your API request.

```bash theme={null}
curl -X POST https://api.arnio.co/messages/send \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "+15555555555",
    "body": "Check out this voice note 🎤",
    "media_url": "https://your-public-bucket.s3.amazonaws.com/voicenote.caf"
  }'
```

### Response

* The response will be the same as a regular outbound message. The only difference is the media\_url will be the URL of the voice note you uploaded.

### Troubleshooting

Often times, it is desirable to convert the audio file from another format, such as MP3. This can be done using the ffmpeg library, and requires the codec to be set as opus or libopus Here’s an example of how to convert an MP3 file to a .caf file:

```bash theme={null}
ffmpeg -i input.mp3 -acodec opus -b:a 24k output.caf
```