Switching network employing an improved interconnection

A multiple-stage automatic switching network in which each stage of the network comprises a plurality of matrices comprised of intersecting input and output conductors, and in which the network includes a multiple-stage line selection unit at one end of the network and a multiple-stage group selection unit at the other end thereof, an intermediate distributing frame for interconnection of output conductors of the final stage of said line unit and the input conductors of the first stage of said group selection unit, a first plurality of links across said distributing frame, said links being individually disposed between an output conductor of the final stage of said line unit and an input conductor of the first stage of said group selection unit for the processing of calls serially through the stages of said network, a plurality of loop circuits at said frame, each said loop circuit having connection through terminals at said intermediate distributing frame to two input conductors of the first stage of said group selection unit for the return of calls serially transmitted from the output conductors of the final stage of said group selection unit serially doubled back through the stages of said group selection unit, with said links and said loop circuits interspersed on said distributing frame.