public function toBinary()
    {
        /**
         * @todo There is no documentation on the reserved data, but this is how it seems to act. May need to change this.
         */
        if (!$this->tsPropertyArray && !$this->dialInData) {
            $binary = $this->encodeReservedData('');
        } elseif ($this->tsPropertyArray && $this->dialInData) {
            $binary = $this->encodeReservedData(self::RESERVED_DATA_VALUE['NPS_RDS']);
        }