I have one payment gateway that has only php api. Is it possible to run that script inside my IIS server on application that will run MVC4?
When I add 1.php to my root folder and try to navigate it it shows HTTP Error 404.3 - Not Found.
You have to install PHP with FastCGI on the IIS server. That should configure it to support .php extension. It can be installed with http://www.microsoft.com/web/downloads/platform.aspx
Next you have to configure the routing to ignore requests to this page (otherwise it will assume that the name is actually a name of a controller).
HTTP Error 404.3 - Not Found