System for routing multicast page/party call audio among voice over internet (VoIP) devices in different local area networks (LANs) via internet

A gateway configured to send Internet protocol (IP) unit multicast audio call traffic via the Internet comprising:

• a communications interface to a local area network (LAN) to which IP units are connected, the IP units being configured to send and receive page audio with respect to other IP units and to participate in a party line call with other IP units using multicasts;
• a communications interface to the Internet;
• a memory device configured to store
• an IP address for each of one or more gateways in at least one designated inter-LAN group that are located in different LANs and that perform inter-LAN communication with the gateway, and
• configuration information comprising sockets for page audio and party line calls assigned to the IP units in the LAN;
• a processor configured to
• request from a remote database the IP addresses of the gateways that are assigned to each inter-LAN group that performs inter-LAN communication with the gateway and to store the IP addresses in the memory device, each inter-LAN group comprising designated IP units from different LANs that can communicate with each other via multicast,
• receive a multicast from an IP unit in the LAN and convert the multicast to respective unicasts using the IP addresses of gateways in the designated group that corresponds to the multicast before transmission thereto via the Internet, the multicast destined for IP units in one or more different LANs that correspond to the designated inter-LAN group, and
• receive unicasts from the Internet and convert the unicasts to a multicast provided to a corresponding socket based on the configuration information of the IP units in the LAN.