I've found that toying with the routing url here helps twilio to route the call. I get the error when I leave it blank, but get a demo twilio response when I leave the demo url https://cdn.discordapp.com/attachments/1228667357849849856/1238579954900537365/image.png?ex=663fccf8&is=663e7b78&hm=d077c5e6d080a7ca0abbcf5c70e802ed8473b25108c8bc7fd6d6f38f68296b1c&