Batch status
Sent once per batch when the batch was created with webhook_mode: BATCH, after every number has a send result (usually 1 to 2 minutes after the request). If a number is still pending after 30 minutes, the webhook is sent anyway with that number as QUEUED_PROVIDER.
Any status change of a number after this webhook (for example, a FAILED reported later by the operator, or a number that was still pending) is notified through the regular messageStatus webhook with batch_id; keep the most recent datetime of each message_id.
A batch that could not be processed is notified with status: FAILED in any webhook_mode. It is delivered to the same destinations and with the same retries as the messageStatus webhook.
Payload
Distinguishes this webhook from the per-message one.
The same batch_id returned in the 202 response.
Number of messages per status (COMPLETED only).
Reason of the failure (FAILED only).
message_id of the numbers that were never processed (FAILED only).

