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