How can you play online in mhfu

You can play it only with AD HOC with 3 other people ( 4players ) but u can also play with the XLink Kai server which is like AD HOC but just that u can play with people on the server.

*Note the website is http://www.teamxlink.co.uk/ and if you want to know more about it copy and paste http://en.wikipedia.org/wiki/XLink_Kai