Accept Payment Online

How does one become a payment gateway for credit card companies like visa and mastercard?

I want to know how I can setup my own payment gateway. In other words if I want to know how someone starts something like paypal or ccavenue(indian payment gateway). No, I am not a vendor who wants to accept payments online rather I want to know how one can setup a system through which merchants can accept payments online. I hope I have made myself sufficiently clear. If info on this is given vis-a-vis India It would be more relevant to me but even otherwise any other info would be of great help as well.

Public Comments

1. Maybey at paypal.com