A point-to-multipoint communications network connecting multiple subscribers to a single communications line. A plurality of subscriber communications interfaces are connected in parallel to form a local group in which one communications interface serves as a master communications interface and the other communications interfaces serve as slaves. Each communications interface may be capable of serving as the master communications interface according to a demand division multiplexing technique, which assigns master status based on upstream data demands. As a communications interface is switched to master status, the communications interface previously holding master status is switched back to slave status. A plurality of communications interfaces can thus be connected to a single communications port without increasing the upstream transmission bandwidth requirements. Each network modem may communicate at a frequency separated from the frequencies of the other network modems, to substantially increase the bandwidth of the transmission medium.