Switching network with crosstalk elimination capability

A switching network comprising:

• a group of incoming lines connected to telephone subscribers;
• a group of outgoing lines intersecting said incoming line group;
• a plurality of switching elements provided at preselected crosspoints formed between these incoming lines and outgoing lines for interconnecting a desired incoming line in said incoming line group and a desired outgoing line in said outgoing line group in response to a call from a subscriber;
• a plurality of ON-state detectors connected to the respective incoming lines for detecting the ON-state of said switching elements in response to variation of current or voltage;
• a plurality of direct current isolating circuits connected to said respective incoming lines for preventing direct currents from flowing between the subscribers and said incoming lines;
• a plurality of OFF-hook detectors connected to these direct isolating circuits for detecting the OFF-hook state of the subscribers;
• a plurality of decision circuits responsive to output signals on said ON-state detectors and output signals of said OFF-hook detectors for determining the state where the subscribers are in the ON-hook state where each incoming line is idle;
• and
• a plurality of grounding means for grounding said incoming lines through impedance elements having a sufficiently low impedance value at a desired frequency band of signals to be exchanged when the output signals of said decision circuits show that the subscribers are in the ON-hook state and each said incoming line is idle.