Send a WhatsApp media message (image, document, audio, video, …) that references a file you have already uploaded with the Upload file endpoint. Pass the media_id returned by that upload.

Each entry sends one media message: set recipient_phone (and a sender, or rely on the stream default) for a new conversation, or conversation_uuid to reply into an existing one. message_content is stored with the message in the inbox but is not delivered as a caption.

Response. HTTP 200 with a task_id and one entry per message. status is false when any message failed: failed entries come first and carry error (hex code) and details; accepted entries carry message_uuid (and conversation_uuid on two-way channels). Match entries by internal_id. Final delivery status is sent asynchronously to your configured webhook.

Authentication: stream token in the Authorization header (see Authentication in the API Overview).