ReasonEnum:
| "Fraud"
| "Not enough credit"
| "Blocked"
| "Denied by callback"
| "Invalid callback"
| "Internal error"
| "Destination denied"
| "Network error or number unreachable"
| "Failed pending"
| "SMS delivery failure"
| "Invalid CLI"
| "Invalid code"
| "Expired"
| "Hung up without entering valid code"
| string
Displays the reason why a verification has
FAILED, wasDENIED, or wasABORTED.