A system for the transmission of group multimedia data to a set of clients affiliated to a communication group, the communication system including a control entity; a signaling participating entity; a participating entity supporting a unicast distribution service, called unicast entity; a participating entity supporting a broadcast distribution service, called broadcast entity; the communication system including a software bus linking the different participating entities to convey information messages exchanged between the different participating entities, for: enabling each unicast entity to maintain a first list of multimedia clients for each communication group to which has become affiliated at least one multimedia client; maintain a second list of multimedia clients for each geographic zone; and enabling each broadcast entity to maintain a third list of multimedia clients for each communication group to which has become affiliated at least one multimedia client.