How to host a Halo game online?

I have the Halo trial version and I am able to join other multiplayer games, but when trying to host my own game, others can't join. It also happens if one of my friends tries to host a game as well.

Any solutions?

You are not able to host your own game with the trial version. You need the full Halo version to host custom games. You are able to join other multiplayer games because the hosts of those games have the "full" version.

That is not true. You CAN host on Halo Trial. Those people do NOT NECESSARILY have the full halo game. I do not know how to fix this BUT I just wanted to let you know that that information was INCORRECT! http://answers.yahoo.com/question/accuse_write?qid=20080703100936AANFgiR&kid=LZJRCUHVJTGkUuGDV.Xi&s=comm&date=2009-01-07+13%3A09%3A24&.crumb=