A system for managing internet protocol of at least unicast and/or multicast communications over a network has a network interface 20 for interfacing between the network 10 and other parts of the system. An audio compression/decompression and packetising controller 30 is interposed between the interface 20 and an audio mixer 40 such that the network interface outputs audio signals to the audio mixer for mixing the audio signals at different respective audio levels. An audio channel manager is connected to the controller 30 and audio mixer 40 so as to dynamically allocate audio channels and for connecting the audio mixer to an allocated channel. A message manager 60 is connected to the network interface and to the audio channel manager for managing the unicast and/or multicast communication of the audio signals.