Plural channel switching network with check of marking of channel link

Claim 1

A SWITCHING NETWORK COMPRISING A PLURALITY OF INPUT TERMINALS, A PLURALITY OF OUTPUT TERMINALS, A PLURALITY OF CHANNELS EXTENDING BETWEEN EACH INPUT TERMINAL AND EACH OUTPUT TERMINAL, EACH SAID CHANNEL COMPRISING A PLURALITY OF SWITCHING STAGE MEANS SERIALLY INTERCONNECTED BY A PLURALITY OF LINKS BETWEEN THE RESPECTIVE INPUT AND OUTPUT TERMINALS, WHEREBY THE LINKS OF A CHANNEL HAVE FIRST, SECOND AND THIRD POTENTIALS WHEN SAID CHANNEL IS FREE, BEING MARKED, AND BUSY, RESPECTIVELY, MEANS FOR CHECKING THE STATES OF SAID LINKS, AND MEANS CONNECTING A PLURALITY OF SAID LINKS TO SAID CHECKING MEANS, SAID CHECKING MEANS COMPRISING MEANS RESPONSIVE TO THE POTENTIALS ON SAID LINKS FOR SEPARATELY INDICATING THE ABSENCE OF SAID SECOND POTENTIAL ON ALL LINKS CONNECTED THERETO, THE PRESENCE OF SAID SECOND POTENTIAL ON ONLY ONE LINK CONNECTED THERETO, AND THE PRESENCE OF SAID SECOND POTENTIAL ON MORE THAN ONE LINK CONNECTED THERETO.