Showing papers on "Circuit switching published in 1969"

Module switching apparatus with status sensing and dynamic sharing of modules

Abstract: An input/output interface switching apparatus for switching I/O interfaces connecting I/O control units between channels. The I/O interface switching apparatus provides means for attaching one or more strings of control units to one or more channels and provides a means for switching these strings of control units between the channels under configuration control. The switching apparatus is so arranged that a single failure within one interface affects at most only the channel to which the interface is associated. A switching matrix is provided, within the apparatus, which is physically centralized to minimize the number of I/O interface cables and connectors. The switching functions are, however, logically decentralized from a reliability standpoint so that a single component failure will not result in total switching system failure.

Call forwarding arrangement for telephone answering service systems

Abstract: A central office, comprising a main switching network and control circuitry for interconnecting line circuit appearances and trunk circuit appearance in the normal manner, is modified by the addition of an auxiliary switching network upon which are terminated telephone answering board incoming trunks and call forwarding trunks. These trunks also appear at respective remote telephone answering switchboards and each has a line circuit appearance in the main switching network. The system is arranged so that an incoming connection via a telephone answering board incoming trunk may be extended to a remote destination via a selected call forwarding trunk under control of the telephone answering board. A controller circuit associated with the auxiliary switching network is responsive to control signals from the remote telephone answering switchboard to enable a connection between the activated telephone answering board incoming trunk and the selected call forwarding trunk via the auxiliary switching network located at the central office.

Transceivers with calling devices

Abstract: In a transceiver provided with a calling device, the circuit constant of an oscillator is varied by means of a switching circuit to generate a call signal of multiple frequencies and the switching circuit is controlled by a control circuit.

Method and apparatus for identifying paths through a switching network

Abstract: A telephone system including a switching network wherein memory circuits are provided for each of the links in the switching network to identify and select cross-points for providing connections through the switching network. Each link that forms a portion of a connection through the network is assigned a time slot corresponding to that assigned to its connected junctor circuit. The cross-points in each connected link of a particular connection are identified by scanning the memory circuits of the links assigned to a common time slot.