Required Ports
                                          through Each Firewall
                                          Complex for Border
                                          Controllers:
                                          1719 UDP
                                          1720 TCP
                                          2776 TCP & UDP
                                          2777 TCP & UDP



Public Internet
               External Firewall
                Complex



                               Internal Firewall
                                 Complex



        Direction ports
       need to be opened




                         Direction ports
                          need to be
         Border Controller         opened




                                      k
                                    or
                                   w
                                  et
                                  N
                                 al
                               rn
                              te
                             In
                                    Internal Gatekeeper