public function fundTransfers(
        $oauth_token,
        $amount,
        $sourceAccountNumber,
        $beneficiaryAccountNumber,
        $referenceID,
        $remark1,
        $remark2,
        $transactionID
    ) {
        $corp_id = $this->settings['corp_id'];
        $apikey = $this->settings['api_key'];
        $secret = $this->settings['secret_key'];

        $uriSign = "POST:/banking/corporates/transfers";
        
        $isoTime = self::generateIsoTime();

        $headers                    = array();
        $headers['Accept']          = 'application/json';
        $headers['Content-Type']    = 'application/json';
        $headers['Authorization']   = "Bearer $oauth_token";
        $headers['X-BCA-Key']       = $apikey;
        $headers['X-BCA-Timestamp'] = $isoTime;

        $request_path = "banking/corporates/transfers";
        $domain       = $this->ddnDomain();
        $full_url     = $domain . $request_path;

        $bodyData                             = array();
        $bodyData['Amount']                   = $amount;
        $bodyData['BeneficiaryAccountNumber'] = strtolower(str_replace(' ', '', $beneficiaryAccountNumber));
        $bodyData['CorporateID']              = strtolower(str_replace(' ', '', $corp_id));
        $bodyData['CurrencyCode']             = 'idr';
        $bodyData['ReferenceID']              = strtolower(str_replace(' ', '', $referenceID));
        $bodyData['Remark1']                  = strtolower(str_replace(' ', '', $remark1));
        $bodyData['Remark2']                  = strtolower(str_replace(' ', '', $remark2));
        $bodyData['SourceAccountNumber']      = strtolower(str_replace(' ', '', $sourceAccountNumber));
        $bodyData['TransactionDate']          = $isoTime;
        $bodyData['TransactionID']            = strtolower(str_replace(' ', '', $transactionID));

        // Harus disort agar mudah kalkulasi HMAC
        ksort($bodyData);

        $authSignature = self::generateSign($uriSign, $oauth_token, $secret, $isoTime, $bodyData);

        $headers['X-BCA-Signature'] = $authSignature;

        \Unirest\Request::curlOpts(array(
            CURLOPT_SSL_VERIFYHOST => 0,
            CURLOPT_SSLVERSION => 6,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_TIMEOUT => $this->settings['timeout'] !== 30 ? $this->settings['timeout'] : 30
        ));

        // Supaya jgn strip "ReferenceID" "/" jadi "/\" karena HMAC akan menjadi tidak cocok
        $encoderData = json_encode($bodyData, JSON_UNESCAPED_SLASHES);

        $body     = \Unirest\Request\Body::form($encoderData);
        $response = \Unirest\Request::post($full_url, $headers, $body);

        return $response;
    }