32503: Voice Conversation: Callback event response error.
PROGRAMMABLE VOICE
WARNING
Request to status callback URL received a response error from the customer-side server.
- This error indicates that Twilio was able to reach the customer-provided URL, however, received an error from the customer-side callback endpoint.
- The URL provided was likely valid, but Twilio might be receiving an error from the customer-side service.
- Make sure you have a web server up and running that serves that URL with the configured method in TwiML, e.g. POST.