I am a BBS/door guru, but have very little experience with Java. In general, I think Java has not had a lot of traction as a platform for writing BBS doors. If you can find a way to construct a socket object
and specify the underlying descriptor/handle that should be used (rather than opening a new socket), then that should get you started. I'm not
sure "ServerSocket" is the right thing as that *sounds* like a listening socket which is not really what you want. The socket is already
connected (no bind/listen/accept required).

You may be right the ServerSocket API may not be what I need. I had tried
to open an OutputStream usign a number of different methods but it just
locked the BBS user up completely.

Should the handle be the only thing I would need or do I need to specify a
baud rate somewhere?

--- Mystic BBS v1.12 A45 2020/02/18 (Windows/32)
* Origin: Daves BBS (1:123/180)