You should add the Callback URL in the Onboarding Worksheet. Once you send the completed onboarding worksheet back to Sinch, we can configure the Callback URL on our side. You will then be able to receive responses and view the statuses of sent messages.
Note: You can specify multiple callback URLs.
For changes to the callback after provisioning, please contact Sinch Support.
Refer to the WhatsApp Callback section of the Sinch WhatsApp Business API Documentation for more details.
Learn more about the Sinch WhatsApp Business API.