A voice over internet protocol unit comprising: a voice over internet protocol control module for voice over internet protocol operations among voice over internet protocol units in an Internet Protocol network, the voice over internet protocol control module configured to selectively establish point-to-point communication between its voice over internet protocol unit and another voice over internet protocol unit, and multicast communication among a plurality of the voice over internet protocol units, wherein voice over internet protocol units are end points that use Session Initiation Protocol; an Internet Protocol network interface module connected to the voice over internet protocol control module and to the Internet Protocol network and configured to exchange bi-directional Ethernet data between the Internet Protocol network and the voice over internet protocol control module; a speaker; a microphone; and a user input device coupled to the voice over internet protocol control module for initiating a connection to at least one of an operator station and one or more of the other voice over internet protocol units via the Internet Protocol network, wherein the operator station is a second voice over internet protocol unit; wherein the voice over internet protocol control module is further configured to initiate a call to the operator station and manage a party call with one or more of the other voice over internet protocol units, and to join a party call initiated by another one of the voice over internet protocol units, and wherein the voice over internet protocol unit determines if a multicast stream associated with the operator station is present before initiating a call to the operator station, and when the voice over internet protocol unit determines that the multicast stream associated with the operator station is present, the voice over internet protocol unit is configured to use the multicast stream associated with the operator station as send audio from the operator station and to transmit its send audio on a second multicast channel, and when the voice over internet protocol unit determines that the multicast stream associated with the operator station is not present, the voice over internet protocol unit is configured to initiate a call to the operator station; and wherein, when the voice over internet protocol unit initiates the call to the operator station, the voice over internet protocol control module is further configured to mix two audio streams together comprising the voice over internet protocol unit's send audio from the voice over internet protocol unit to the operator station and the operator station's send audio from the operator station to the voice over internet protocol unit, and to retransmit the two mixed audio streams as a multicast stream to the plurality of the voice over internet protocol units. a voice over internet protocol control module for voice over internet protocol operations among voice over internet protocol units in an Internet Protocol network, the voice over internet protocol control module configured to selectively establish point-to-point communication between its voice over internet protocol unit and another voice over internet protocol unit, and multicast communication among a plurality of the voice over internet protocol units, wherein voice over internet protocol units are end points that use Session Initiation Protocol; an Internet Protocol network interface module connected to the voice over internet protocol control module and to the Internet Protocol network and configured to exchange bi-directional Ethernet data between the Internet Protocol network and the voice over internet protocol control module; a speaker; a microphone; and a user input device coupled to the voice over internet protocol control module for initiating a connection to at least one of an operator station and one or more of the other voice over internet protocol units via the Internet Protocol network, wherein the operator station is a second voice over internet protocol unit; wherein the voice over internet protocol control module is further configured to initiate a call to the operator station and manage a party call with one or more of the other voice over internet protocol units, and to join a party call initiated by another one of the voice over internet protocol units, and wherein the voice over internet protocol unit determines if a multicast stream associated with the operator station is present before initiating a call to the operator station, and when the voice over internet protocol unit determines that the multicast stream associated with the operator station is present, the voice over internet protocol unit is configured to use the multicast stream associated with the operator station as send audio from the operator station and to transmit its send audio on a second multicast channel, and when the voice over internet protocol unit determines that the multicast stream associated with the operator station is not present, the voice over internet protocol unit is configured to initiate a call to the operator station; and wherein, when the voice over internet protocol unit initiates the call to the operator station, the voice over internet protocol control module is further configured to mix two audio streams together comprising the voice over internet protocol unit's send audio from the voice over internet protocol unit to the operator station and the operator station's send audio from the operator station to the voice over internet protocol unit, and to retransmit the two mixed audio streams as a multicast stream to the plurality of the voice over internet protocol units.