Maybe it will help somebody. I found very strange solution, but it works ) I activated additional random server message, in my case "session.created" and now I get webhook "end-of-call-report" in all cases, including when I have error "call.in-progress.error-providerfault-outbound-sip-480-temporarily-unavailable" . Magic 🧙 But also I see validation error, but anyway assistant works. @Vapi it looks like a bug https://cdn.discordapp.com/attachments/1211484481848873020/1430902154306129980/image.png?ex=68fb76fa&is=68fa257a&hm=9faf76a9dce24bc06bb6bd755c6566670a8aa3b4c606ab49b0ad1e38eebbd301&