Natwest Streamline is not one of the pre integrated credit card payment gateways in SmithCart but the cart has a Custom Web Service gateway option which allows you to plug-in any gateway provider you desire. The custom web service gateway option performs an https post operation to the url you enter in the “URL” field under the cart gateway settings. It is a standard https post “Request – Response” with hidden name value pairs (NVP). If you would like a quote to integrate Natwest as a certified payment gateway in Smith Cart please send an email to sales@smith-consulting.com.