CPC Main Group H04L 5/00 Arrangements affording multiple use of the transmission path 7 direct subcodes Child Classifications Navigate with arrow keys, Enter to open H04L 5/0001 H04L 5/003 H04L 5/0091 H04L 5/02 Channels characterised by the type of signal H04L 5/14 Two-way operation using the same type of signal, i.e. duplex H04L 5/20 using different combinations of lines, e.g. phantom working H04L 5/22 using time-division multiplexing