Twilio was unable to parse the provided XML Document.
Your TwiML document must be a valid XML Document, or Twilio will not be able to read your document. You can debug XML parsing errors by getting the response body in the debugger, and then using an online validation tool like the W3C Validation Service.
Twilio's HTTP client does not support chunked transfer encoding. If your server
responds to a request for TwiML with the HTTP header
Transfer-Encoding: chunked' and your TwiML
document is larger than the size of one chunk it will be truncated, which often
results in a 12100 error. Dividing up large TwiML documents into smaller
sections and using multiple
<Redirect> verbs to route between them
is the best way to get around this issue.
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