Networking different FS versions

Is it possible for users of different MS FS versions to join a multiplayer game?
Suppose a FS2004 user hosts a multiplayer session and a FS98 user connects directly to the first user's IP address.
Is it possible at all or do all participants need to run the same FS version?
Suppose a FS2004 user hosts a multiplayer session and a FS98 user connects directly to the first user's IP address.
Is it possible at all or do all participants need to run the same FS version?