Use POST /v1/whatsapp/messages/audio for voice notes and audio clips. Point at a publicly reachable media_url; WhatsApp fetches it at send time, so it must be reachable then and serve the correct Content-Type. Needs an open 24-hour window.
WhatsApp audio messages do not support a caption or filename — there is no caption field on this endpoint.
Endpoint
POST https://karibu.briq.tz/v1/whatsapp/messages/audio
X-API-Key (required), Content-Type: application/json.
Fields
| Field | Type | Required | Notes |
|---|
media_url | string | one source | Public HTTPS URL to the audio file. |
file_id | string | one source | Uploaded media id (first-party). Use media_url for external integrations. |
to + sender | — | target | Customer number (E.164) and which of your numbers to send from. sender is optional when you have one active number. |
conversation_id | uuid | alt | Alternative to to + sender: an existing thread to reply in. |
Constraints
| |
|---|
| Formats | AAC (audio/aac), AMR (audio/amr), MP3 (audio/mpeg), M4A (audio/mp4), OGG (audio/ogg, OPUS codec only) |
| Max size | 16 MB |
131053 error usually means OGG that is not OPUS-encoded, or a file over the limit.
Example
curl -X POST "https://karibu.briq.tz/v1/whatsapp/messages/audio" \
-H "X-API-Key: YOUR_API_KEY" -H "Content-Type: application/json" \
-d '{ "to": "255712345678", "media_url": "https://example.com/voice-note.ogg" }'
{ message_id, status: "pending" }. Then track delivery. Build and send a live request from the Send an audio message reference page. 
