A system for implementing multiple communication channels on a single
twisted pair transmission line is disclosed. The system derives additional
communication channels by way of a separate transceiver unit for each
derived line. Each transceiver unit communicates in a separate
predetermined frequency band. Each transceiver unit, upon connection to
the transmission line, automatically utilizes the lowest unoccupied
frequency band by monitoring each frequency band for the presence of
signal poser. Thus, as many derived lines as will be supported by the
customer transmission loop can be readily added.
