A cluster of terminals, and an ad-hoc network of two or more such clusters, for carrying a multi-party, cluster-based, conference, wherein each cluster includes a super member comprising a super user agent, and one or more members including a user agent. Communications sessions are established between the super member of each cluster and each member terminals of the same cluster, and between the super members of each one of the first and second clusters. The user agent comprises identity of the super member, a conference identity, cluster parameters including a split value (Sv) indicative of a maximum number of terminals that may be part of the cluster, wherein when Sv is reached during the conference the cluster is split, and a merge value (Mv) indicative of a minimum number of terminals that may be part of the cluster, wherein when Mv is reached the cluster is merged with another cluster. The super user agent comprises a cluster member list, the conference identity, a cluster neighbour list, the one or more terminals also participating to the same conference, and cluster parameters.