Web Forms :: How To Use Same Number Of Parameters For Two Pages In URL Routing

I have some routes defined in global.asax according to which the page is redirected.

 Global.asax
void Application_Start(object sender, EventArgs e) {
RegisterRoute(System.Web.Routing.RouteTable.Routes);
} void RegisterRoute(RouteCollection routes) {
routes.MapPageRoute("MainCategory", "{state}/{mcat}", "~/MainCategory.aspx");
routes.MapPageRoute("carriers", "{state}/{mcat}/{dcat}", "~/carriers.aspx");
routes.MapPageRoute("carrierdevices", "{state}/{mcat}/{dcat}/{carrier}", "~/carrieritems.aspx");
routes.MapPageRoute("cellphone", "{state}/{mcat}/{dcat}/{carrier}/{device}/{id}", "~/Catalog.aspx");
//New Rout with same parameters
routes.MapPageRoute("iphones", "{state}/{mcat}/{dcat}", "~/iphones.aspx");
}

i mean to say how to decide the destination page depending on URL Eg:1.routes.MapPageRoute("carriers", "{state}/{mcat}/{dcat}", "~/carriers.aspx"); 2.routes.MapPageRoute("iphones", "{state}/{mcat}/{dcat}", "~/iphones.aspx");

if value in URL second parameter i.e mcat=cellphone then it must redirect to carriers.aspx. and if mcat=iphone then it must redirect to iphones.aspx page.

Problem:currently if in URL there are 3 parameters then it always goes to carriers.aspx as it searches in route table for 3 parameters it redirects to carriers.aspx which need to be conditionally redirected depending on mcat valuehow to do?