I think you should open the RMI port also (4444 ?).
AFAIK, the 1099 port is used to look up the object. This port must be open.
After that, the RMI system opens up the RMI data port and listens on this port for the actual work to do.
Last time I looked (with JBoss 2.4.3), this data port was not fixed but random. The appropriate setting was "RmiPort".
When you're behind a firewall you MUST set this since obviously you don't want to open ALL ports in your firewall.