If I have a IP and a server on DHCP why is it that an "outside" entity is not able to access the service.
a) What is your local network configuration:
Do you have a router? If so, then Joe answered your question.
Or are you directly connected to your ISP? If so, then does your ISP route traffic to your IP address, or does it block it?
b) Is there a firewall somewhere (either in your network or the IPS's) that is preventing the access.
c) What network debugging have you done (ping, tracert, etc) and what were the results of each of those?
d) If you do an ifconfig, what is the first node number? Is it 192?