Your system specifications might require that you define other interfaces.

The Primary Management IP address (PMI) is the IP address assigned to Branch Gateway. Branch Gateway uses PMI for self-identification when communicating with other devices, particularly the Media Gateway Controller (MGC). Management data intended for the Branch Gateway is routed to the interface defined as PMI. You can use any interface as the PMI. The PMI address can be IPv4 or IPv6.

The MGC is a call controller server that controls telephone services on the Branch Gateway. The MGC can be internal or external and either IPv4 or IPv6.