I have been trying to build a app that redirect a Twilio number to another phone number when a customer call Twilio number. When callback URL does not return proper Twilml, it says "Application has failed" message on the call. However, I do not want my customers hear that message even though there is a error. Is there a way to turn that message off?
Thank you.
Twilio evangelist here.
There is no way to disable the error message, but you can set a Fallback URL on your phone number that Twilio will request in case the Voice Request URL fails.
You could set the Fallback URL to a simple static XML file hosted somewhere like Amazon or Dropbox, or use a service like twimlbin.com to host some backup TwiML for you.