public function setPremiumSms($shortcode, $keyword, $tariff, $mid = null, $member = null)
    {
        $this->typeDetails['shortcode'] = $shortcode;
        $this->typeDetails['keyword']   = $keyword;
        $this->typeDetails['tariff']    = $tariff;
        if ($mid != null) {
            $this->typeDetails['mid'] = $mid;
        }
        if ($member != null) {
            $this->typeDetails['member'] = $member;
        }

        $this->type = self::TYPE_PREMIUM;
    }