Abstract: A communication system having full call processing capabilities in the user ports, each port being connected to a TDM collection bus and a TDM distribution bus. A bus controller terminates the collection bus on which voice words are deposited in time slots by the respective user ports, the voice words being realigned and transmitted by the bus controller on the TDM distribution bus. Each user port is assigned a time slot and can thus communicated simultaneously with one or more other user ports, such as during a two-way telephone conversation or a multiple party conference call. A memory in each user port combines plural voice words obtained from respective TDM time slots of conference participants, and combines such voice words into a composite signal representative of all the other conferees. The conference circuit of each user port combines the voice words of all the other participating ports over a frame period, except its own voice word, and thus the composite voice word of each user port is different.