A method and computer program product which allows both phone-based and IP-based clients to participate in a single audio conference. The method enables at least two multi-point control units (MCUs) (i.e., conferencing servers) to connect via a standard data linkage (i.e., full-duplex dial-up or IP link). The method and computer program product enables the phone-based MCU to handle the phone clients and the IP-based MCU to handle the IP-based clients, while connecting the two to allow each participating client to hear all other participating clients.