720001: a TwiML verb or attribute isn't supported in v1

HTTP status

400

Where you see it

HTTP (Twiml=) / StatusCallback

Why it happens

• A refused verb (e.g. Say, Record, Dial to a number), an unsupported attribute value, or Dial><Sip anywhere but first on an incoming call. reason names the verb or attribute.

Extra fields in the error

Besides code, message, more_info and status, the error body carries: reason. The message says the same in words.

The error body

{
  "code": 720001,
  "message": "a TwiML verb or attribute isn't supported in v1",
  "more_info": "https://docs.dongleswithwings.com/errors/720001",
  "status": 400
}