A first group auditory data stream, from a transmitting subscriber device of a first group of subscriber devices or from a dispatch console and intended for the first group of subscriber devices, is received at a conference server. The conference server determines whether the first group auditory data stream generated for the first group of subscriber devices is of interest to a second group of subscriber devices, and if so, sums the first group auditory data stream with a second group auditory data stream intended for the second group of subscriber devices to form a summed group auditory data stream. The conference server then forwards the summed group auditory data stream towards the second group of subscriber devices and forwards the first group auditory data stream towards the first group of subscriber devices.