Properties of a DtmfInput.
Properties:
| Name | Type | Attributes | Description | 
|---|---|---|---|
digits | 
      
      string | null | 
            
              <optional> | 
        
        
        
           DtmfInput digits  | 
    
finishDigit | 
      
      string | null | 
            
              <optional> | 
        
        
        
           DtmfInput finishDigit  |