Yes, that's correct. If the webhook works with manual tests, it suggests that there are no connectivity issues. Regarding the workflow, a workflow might be necessary to make calls work, as you've already tried creating a workflow but it failed. You may want to investigate further why the workflow failed or consider reconfiguring it to see if that resolves the issue with your VAPI agent sending data through the webhook after calls end. I'd be happy to help you investigate further and get your Vapi agent up.