Halo 3 - search for online co-op game?

I just got Halo 3, pretty awesome game. However, I can't figure out how to search for a co-op online game. Is this feature even possible?





I found the matchmaking and stuff but to me it seems the online co-op is restricted to friends only or invites. I couldn't find or figure out how to join an online co-op game. If it exists, can someone explain how to do it?





Thanks!

Halo 3 - search for online co-op game?
yep, make some friends online multiplayer, and then invite one or more to the campaign.

puppy teeth