A method and system for establishing and managing subconference calls within a main conference call includes a subconference call subsystem (30) which responds to a subconference call request (28) from a first terminal (14) during the main conference call by transmitting (58) the subconference call request to a second terminal (24). The subconference call subsystem monitors (60) a connection to the second terminal to detect a signal indicating acceptance of the request. Upon detecting an acceptance, the subconference call subsystem establishes (62) a first subconference call and a data mixer (34) mixes (66) first voice data (42) from the main conference call with simultaneously transmitted second voice data (38) generated from the first and second terminals. A data router (36) transmits (68) the mixed first and second voice data (40) to the first and second terminals without transmitting the second voice data to any of the other terminals participating in the main conference call. Furthermore, the process of establishing subconference calls is transparent to the other main conference terminals. The subconference call terminal subsystem can establish (73) a second subconference call and can switch (80 and 82) a terminal for bi-directional voice transmissions within the main conference call, the first subconference call, or the second subconference call.