Can you still use Dreamcast online?

I was thinking today, can you still play some online games on the Dreamcast? If so, which ones can you play, and how well do they run with the provided 56k modem?

I'm gonna jump out and guess that in the same way most PS2 online games have been shut down, so have the Dreamcast ones. BUT, I'm just guessing here.

I heard that people were still playing Phantasy Star Online. I don't know if that's actually true though. 
 
Edit: Here's a private server.

Back in the day I played Quake 3 online on Dreamcast (with mouse and keyboard, lol).  It was cool.  It was my first online FPS.  I SUUUCKED.

I have heard that you can´t play online because they closed the servers long time ago  for the DC. :S

I know that the Saturn and Jaguar were all done P2P, so those would work as long as you knew the other guys phone number (this is a hazy remembrance, it might be a smidge more complicated than that). I think that some Dreamcast games also work this way, mostly early ones. Obviously anything with more than two players would get problematic...

just ain't worth it dude.