I like Zen cart and want to use it for a client's online store. The main issue is that my client is located in the carribean and she has a merchant account with her local bank. They have sent me information to use their payment gateway but I don't know how to incorporate it with Zen Cart.

The payment gateway is through 4C's (Caribbean Credit Card Company) and it uses a method for calling it's payment gateway (FMX TranPage) that utilizes iframes. To initiate a transaction, your system must generate a POST action inside of the contained IFRAME on the page with a form in between which holds the invoice number, total amount, unique transaction id, etc.

Is there a way to modify one of the payment gateway that would allow me to utilize this method? If so, which payment gateway would be the best to use?

If anyone would like to offer some direction and needs to see the instructions I received from the merchant I would be happy to send the PDF file showing the Integration Guide.

(sorry for the long windedness)