port mapping to terminal services

I recently installed terminal services on my 2000 Server. I can connect internally but when I request to connect to the public ip address, I can’t seem to get a connection. I am running NAT on my router that translates the internal ip to the public. Is there a tcp-ip port that I would have to map to the server in the router in order for the terminal clients to access the server? If so, then what port does terminal services for Windows 2000 server use? Thank You