My company would like to use the Notification Delivery Callback functionality, but have the Visa on-behalf-of Alert Delivery Service deliver the alert if our callback URL is unreachable or doesn't return a success code. Is this a configuration that anyone is using?
Our VTC product team is evaluating this use case. We will get back to you soon.
It turns out to be like you can choose either Alert Delivery or Notification call back but not both. So Alert delivery cannot fall back notification call back.
Hope this helps !