Multistage telephone switching system for different priority users

Claim 2

A switching system comprising: an odd-numbered plurality of switching stages including end stages and a middle stage, each of said end stages comprising a plurality of similar matrices, a plurality of links coupling said end stages to said middle stage and defining a plurality of cross-points a first plurality N1 of input lines given a substantially nonblocking probability, and a second plurality N2 of input lines having a predetermined degree of nonzero blocking probability, coupled to selected matrices in said end stages, said middle stage being partitioned into a plurality of switching sections, each performing an independent switching function, each of said switching sections having a different number of cross-points corresponding the the values of N1 and N2, and having a predetermined number of matrices.

Claim 3

The system of claim 1 in which said system is a three-stage system.

Claim 4

The system of claim 1 in which said system includes five stages in which three middle stages are a Clos folded three-stage array, the middle stage of said Clos being partitioned.

Claim 5

A switching system comprising a plurality of switching stages, a plurality of lines, each of said lines having at least one line termination in each of at least two of said stages, the primary stage and the end stage, a middle switching stage coupled to said at least two stages and defining a plurality of cross-points, any pair of line terminations being obtained through different connections of the cross-points, at least one middle bank of a plurality of interstage links, the number of cross-points connecting the interstage links being less than that required for nonblocking service, electrical circuit means including link seeking means operable to seek an available permutative pair, said at least two switching stages having an equal plurality of similarly numbered matrix substages, a plurality of called and calling lines, each substage having an equal plurality of similarly numbered line terminals, and each line having a line termination in one line terminal of one substage of a first stage and another line termination in the similarly numbered line terminal of the similarly numbered substage of a last stage, a plurality of interstage links divided into subgroups of links including different groups serving different pairs of substages taking one substage from each stage, said middle stage being partitioned into subsections which have independent switching functions for the different priority users involved, thereby allowing efficient arrays to be designed to afford different grades of service to the users according to priority.

Claim 6

A switching system comprising a plurality of switching stages, a plurality of lines, each of said lines having at least one line termination in each of at least two of said stages, the primary stage and the end stage, a middle switching stage coupled to said at least two stages and defining a plurality of cross-points, any pair of line terminations being obtained through different connections of the cross-points, at least one middle bank of a plurality of interstage links, the number of cross-points connecting the interstage links being less than that required for nonblocking service, electrical circuit means including link seeking means operable to seek an available permutative pair, said at least two switching stages having an equal plurality of similarly numbered matrix substages, a plurality of called and calling lines, each substage having an equal plurality of similarly numbered line terminals, and each line having a line termination in one line terminal of one substage of a first stage and another line termination in the similarly numbered line terminal of the similarly numbered substage of a last stage, a plurality of interstage links divided into subgroups of links including different groups serving different pairs of substages taking one substage from each stage, said middle stage being partitioned into subsections which have independent switching functions for the different priority users involved, thereby allowing efficient arrays to be designed to afford different grades of service to the users according to priority.

Claim 7

The system of claim 4 in which said middle switching stage is divided into a first section used for connections among the high priority lines, second and third sections for use with connection between a high priority line in a first group and a second line in a low priority group, and a fourth section used for connections only among the low priority lines.

Claim 8

The system of claim 4, having at least five of said switching stages, the intermediate ones of said switching stages being nonblocking Clos type arrays with the center stage being partitioned.