A bidirectional multipoint-to-point communications system for sending payload information over a distribution network is provided. The system includes a head-end terminal coupled to the distribution network to a plurality of service units. The head-end terminal includes a head-end controller for sending payload data to and from an external communications network and for producing and processing control messages at the head-end terminal, a head-end multicarrier transmitting modem coupled to the head-end controller for modulating downstream payload information and downstream control messages onto multiple orthogonal carriers spread throughout substantially all of a first frequency band, and a head-end multicarrier receiving modem coupled to the head-end controller for demodulating multiple orthogonal carriers spread throughout substantially all of a second frequency band and carrying upstream payload information and control messages. Each of the service units receives the downstream control messages and downstream payload information over only a portion of the first frequency band, and each of the service units transmitting only a portion of the upstream control messages and upstream payload information. Each of the service units includes a service-unit controller, a service-unit multicarrier receiving modem, and a service-unit multicarrier transmitting modem.