Multistage telephone switching network

Claim 2

An automatic telecommunication exchange, in which connections are set up via cascaded stages of coordinate matrices, there being four of said stages referred to hereinafter as A switches, B switches, C switches and D switches respectively, in which the devices served include subscribers'' lines and incoming and/or outgoing junctions which are connected to A switch outlets, in which said devices served are divided into two groups, with a first set of said A switches serving only devices of one group and a second set of said A switches serving only devices of the other group, in which the B and C switches are arranged as a plurality of sections with the B and C switches of each section interconnected as two-stage switching networks, in which each said A switch has a number of inlets at least equal to the number of said sections, each said A switch being accessible from every one of said sections, in which each said BC switch section includes a first set of B switches whose outlets go to A switches of said first set and a second set of B switches whose outlets go to A switches of said second set, in which within each said twostage switching network each said B switch is accessible from every one of the C switches of that network and each C switch has access to every one of the B switches of that section, in which links are provided one of which Is used for each connection to be set up, each said link having one of its two ends connected to a C switch inlet and the other of its ends connected to a D switch inlet, in which the D switch outlets are connected to C switch inlets such that when a D switch is set to connect one of said links between two C switch inlets those C switch inlets belong to C switches in different ones of said sections, and in which each connection between two of said devices is set up by connecting one end of a free link to one of said devices via a C switch, a B switch and an A switch and by connecting the other end of that link to the other of said devices via a D switch, a C switch, a B switch and an A switch, the C and B switches used for the two parts of the connection being in different ones of said sections.

Claim 3

An automatic telecommunication exchange, in which connections are set up via cascaded stages of coordinate matrices, there being four of said stages referred to hereinafter as A switches, B switches, C and D switches respectively, in which subscribers'' lines and incoming and/or outgoing junctions are connected to A switch outlets, said A switches including a first set of switches which only serve lines and a second set of switches which serve junctions, in which the B and C switches are arranged as a plurality of sections with the B and C switches of each section interconnected as two-stage switching networks, in which each said A switch has a number of inlets at least equal to the number of said sections, each said A switch being accessible from every one of said sections, in which each said BC switch section includes a first set of B switches whose outlets go to A switches of said first set and a second set of B switches whose outlets go to A switches of said second set, in which within each said two-stage switching network each B switch is accessible from every one of the C switches of that network and each C switch has access to every one of the B switches of that section, in which links are provided one of which is used for each connection to be set up, each said link having one of its two ends connected to a C switch inlet and the other of its ends connected to a D switch inlet, in which the D switch outlets are connected to C switch inlets such that when a D switch is set to connect one of said links between two C switch inlets those C switch inlets belong to C switches in different ones of said sections, and in which each connection between a first circuit, which is a line or a junction, and a second circuit, which is also a line or a junction, is set up by connecting one end of a free link to one of said circuits via a C switch, a B switch and the A switch to which that one circuit is connected, and by connecting the other end of that link to the other of said circuits via a D switch, a C switch, a B switch and an A switch, the C and B switches used for the two parts of the connection being in different ones of said sections.

Claim 4

An automatic telecommunication exchange, in which connections are set up via cascaded stages of coordinate matrices, there being four of said stages referred to hereinafter as A switches, B switches, C and D switches respectively, in which subscribers'' lines and incoming and/or outgoing junctions are connected to A switch outlets, said A switches including a first set of switches which only serve lines and a second set of switches which serve junctions, in which the B and C switches are arranged as a plurality of sections with the B and C switches of each section interconnected as two-stage switching networks, in which each said A switch has a number of inlets at least equal to the number of said sections, each said A switch being accessible from every one of said sections, in which each said BC switch section includes a first set of B switches whose outlets go to A switches of said first set and a second set of B switches whose outlets go to A switches of said second set, in which within each said two-stage switching network each B switch is accessible from every one of the C switches of that network and each C switch has access to every one of the B switches of that section, in which links are provided one of which is used for each connection to be set up, each said link having one of its two ends connected to a C switch inlet and the other of its ends connected to a D switch inlet, in which the D switch outlets are connected to C switch inlets such that when a D switch is set to connect one of said links between two C switch inlets those C switch inlets belong to C switches in different ones of said sections, and in which each connection between a first circuit, which is a line or a junction, and a second circuit, which is also a line or a junction, is set up by connecting one end of a free link to one of said circuits via a C switch, a B switch and the A switch to which that one circuit is connected, and by connecting the other end of that link to the other of said circuits via a D switch, a C switch, a B switch and an A switch, the C and B switches used for the two parts of the connection being in different ones of said sections.

Claim 5

An automatic telecommunication exchange as claimed in claim 2, in which said second set of A switches also serve registers.

Claim 6

An automatic telecommunication exchange as claimed in claim 2, in which each said link is a reversible device, switching means being provided therein to set the link in accordance with the direction in which it is to be used.

Claim 7

An automatic telecommunication exchange as claimed in claim 2, in which the said links include links of a first sort used for calls which terminate on lines served by the exchange and a second sort used for calls for which an outgoing junction is needed, and in which the links of said first sort include power feed means.

Claim 8

An automatic telecommunication exchange as claimed in claim 5, in which said D switches are split into two sets of switches, one of which sets serves only links of said first set and the other of which sets serves only links of said second set.

Claim 9

An automatic telecommunication exchange as claimed in claim 2, and in which each said section includes a plurality of said two stage switching networks.

Claim 10

An automatic telecommunication exchange as claimed in claim 2, in which said coordinate switching matrices are electromechanical crossbar switches.

Claim 11

An automatic telecommunication exchange as claimed in claim 2, in which said coordinate switching matrices are matrices of electronic devices each settable to an ''''on'''' or an ''''off'''' condition.

Claim 12

An automatic telecommunication exchange as claimed in claim 2, in which said coordinate switching matrices are matrices of sealed contact reed relays.