Q: What ports does the server use?

A: The TeamSpeak Server uses the following ports:
8767 UDP, for the server itself.
Adjustable in the server.ini: ServerUDPPort=8767
14534 TCP, WebInterface
Adjustablein the server.ini: HTTPServer Port=14534
51234 TCP, TCPQuery port
Adjustable in the server.ini: TCPQueryPort=51234

To get server to work behind firewall, nat, masq you need only to open/forward the server port (in the above case: 8767 UDP).