code: function PlivoErrorStatus(status, response) {
    MessagingServiceStatus.call(this, 'plivo');
    
    // There was an error when attempting to send message
    this.state.message = status.toString() + ': ' + response.error;
  
    // See https://www.plivo.com/docs/api/response/ for details
    if (status == 400) this.state.code = this.StatusCodes.DATA_REJECTED;
    else if (status == 401) this.state.code = this.StatusCodes.UNAUTHORIZED;
    else if (status == 404) this.state.code = this.StatusCodes.DATA_REJECTED;
    else if (status == 405) this.state.code = this.StatusCodes.DATA_REJECTED;
    else if (status == 500) this.state.code = this.StatusCodes.SERVICE_DOWN;
    else this.state.code = this.StatusCodes.DEFAULT;
  }
docs: /*
  Error Status
  
  @param response     JSON response object from Plivo service