Telephone switching system with switched line circuits

DETAILED DESCRIPTION What is claimed is: 1.
A telecommunications switching system including, a plurality of line interface circuits for coupling communications signals between channels organized in periodically reoccurring frames in a time division multiplex (TDM) switching network and telephone lines served by the telecommunications switching system, and a call control means being responsive to signalling received from the telephone lines in association with telephone calls, for directing the operations of the time division switching network to provide communications paths via the TDM channels between ones of the telephone lines, the telecommunications switching system comprising: means for coupling each of the line interface circuits with a predetermined one of the channels in the TDM switching network; detector means being connected to each telephone line of a plurality of the telephone lines for detecting a transition from an ON HOOK state to an OFF HOOK state; analog switch means being for connecting each of the telephone lines in the plurality of telephone lines to any one of a limited number of not more than a predetermined half of the line interface circuits, in the plurality of line interface circuits; control means being responsive to a detected transition to the OFF HOOK state, in the state of any one of the plurality of telephone lines, for causing the analog switch means to switch said any one of the plurality of telephone lines to an idle one of said predetermined line interface circuits, and, in an event of none of said predetermined line interface circuits being idle, the control means being responsive to the detected transition to the OFF HOOK state, for causing the analog switch means to re-switch another telephone line, already having been connected to one of said predetermined line interface circuits, to an alternate line interface circuit not within said limited number of line interface circuits and to disconnect said another telephone line from the one of said predetermined line interface circuits, and thereafter for causing the analog switch means to connect said any one of the plurality of telephone lines with the one of said predetermined line interface circuits