Sadly, the GameCube and Dreamcast version of the mega-hit online RPG Phantasy Star Online will not be playable with each other.
When heavily backed rumors said that the Dreamcast and GameCube versions of Phantasy Star Online version2 would be playable over the internet with each other, some were still skeptical. Looks like it's a dream that has not come true. The GameCube version of PSOv2 features some things that the Dreamcast version does not, mainly 2 new characters. Because of this, and other technical problems with getting the systems to talk to each other, the Dreamcast and GameCube versions of PSOv2 will not interact with each other.