Most of systems have their own internal tables to track the sent messages and updating the status. To identify the response for every message we can't just rely on to/from fields because multiple messages can be sent to the same phone number.
Another solution is to let consumer can optionally add RefId field, which will be delivered back in webhook response. Consumer then can use this RefId to update internal tables.
Also, in case of webhook delivery failed for any reason, consumer can query the message status using RefId at any time.