Abstract: In an apparatus for supplying a tip and ring telephone line with voice band and broadband signals, a first pair of drivers supply at least DC signals to the respective tip and ring line components, and a second pair of drivers supply broadband signals to the tip and ring line components. Feed components combine the outputs of said respective drivers for the respective tip and ring components of the telephone line.

Abstract: A subscriber line interface circuit has first and second line drivers for connection to respective tip and ring lines of a subscriber loop. Each of said line drivers is in a feedback loop. A current limiting device is included in each feedback loop for providing protection against excessive current. In this way the effective impedance of the current limiting devices is small relative to their actual impedance and as a result any impedance mismatch between the current limiting devices has a negligible effect on the longitudinal balance of the subscriber loop.

Abstract: In an apparatus for supplying a tip and ring telephone line with voice band and broadband signals, a first pair of drivers supply at least DC signals to the respective tip and ring line components, and a second pair of drivers supply broadband signals to the tip and ring line components. Feed components combine the outputs of said respective drivers for the respective tip and ring components of the telephone line.