tcp/5222 and tcp/5269 ... if you wish people outside your ZCS server to invite internal people then you will need to update your DNS so that servers can find you. You will need a record like this :-
Code:
_xmpp-client._tcp SRV 10 10 5222 {zcs_server_name}.
_xmpp-server._tcp SRV 10 10 5269 {zcs_server_name}.