GB1210792A - Connecting and disconnecting system for switching equipment - Google Patents

Abstract

1,210,792. Automatic exchange systems. INTERNATIONAL STANDARD ELECTRIC CORP. 16 Jan., 1969 [18 Jan., 1968], No. 2560/69. Heading H4K. In an exchange having a switching network consisting of mechanically latched cross-bars, the release of operated cross-points is effected just prior to the setting up of a new connection and not immediately on termination of the connection to which they relate. As shown, looping of a caller's line lg<SP>1</SP> is detected in his line circuit JA1 and the marker MQ connects it via singlestage cross-bar switch CCA to the inlet of oneway feedbridge AL1 if this is free. It should be noted that the feedbridges are one-way, only in respect of call-setting and not in respect of speech transmission and moreover, each group of subscribers may have access to more than one feedbridge via their single switch. The feedbridge seizes a free register EN which reverts dial tone and then accepts dialled digits from the caller. The identity of the called party, e.g. lgm, is passed to the marker and stored on a relay contact tree (Fig. 2, not shown). A relay sequence switch is effective thereafter to successively transmit disconnect signals to the vertical magnets of column 1 in switches CCA and CCC whereby any actuated cross-points in these columns are released. The sequence switch then applies signals to the vertical magnet of column 1 and to the horizontal magnet of row 1 in switch CCB whereby already operated crosspoints, if any, in the column are released and, virtually simultaneously therewith, the required cross-point is closed so as to connect the called line to the outlet s of the feedbridge. The register indicates ringing and then withdraws followed by the marker.