Abstract: A conferencing circuit for use in a digitized voice, time division multiplex (TDM) loop communication system. Digitized speech samples from conferee subscriber stations are extracted from the TDM loop and summed over a frame interval. The sum is stored and the input from each subscriber station is subtracted from the sum and the remainder is placed on the TDM loop for return to the respective station. A conference control signal is generated which is synchronous with the TDM loop and the subscriber station's time slot and has a given state for each slot assigned to a subscriber station that participates in the conference. The conference control signal controls the circuitry which sums the digitized speech samples generated by the conference subscriber stations.