Method and means for connecting branch exchanges

Claim 1

Means for providing that a sub-set of one private branch exchange, may achieve connection to a sub-set of another private branch exchange, through a conventional telephone system, wherein each private branch exchange is connectable to a different central office, by one or more connecting trunks associated with the private branch exchange; and each private branch exchange and its associated trunk are designed so that a private branch exchange sub-set may, on an originating call, seize one of the connecting trunks associated with that private branch exchange; and a private branch exchange sub-set may, on a terminating call, be seized by one of the trunks, associated therewith comprising: first means responsive to the seizure of one of the associated connecting trunks by a sub-set of a private branch exchange, on an originating call, to connect the input of a first registersender and signal conversion means to said seized trunk, said first register-sender being designed and connected to store dial pulse digits signalled from the sub-set to the registersender input and, on receipt of a predetermined signal, to transmit through the signal conversion means a signal, at a frequency within the voice band, containing digital information as to said digits; second means responsive to said seizure of said one of the connecting trunks, for establishing a connection between the central office associated with the seized trunk and the central office associated with the other private branch exchange; a second register-sender and frequency conversion means associated with said other central office being designed on establishment of said connection to receive signals at a frequency within the voice band sent along said connection containing digital information, and on receipt of a predetermined signal, to transmit said digital information in form suitable for achieving connection at said other private branch exchange to a sub-set thereof; means responsive to the establishment of said connection for connecting the output of said first register-sender signal conversion means across said established connection to the signal conversion means of said second register-sender at the other central office; and responsive to the establishment of said connection, to connect the output of said second register-sender at said other central office, to the other private branch exchange; responsive to the connection of said first and second registersender signal conversion means across said connection, to send said predetermined signal to said first register-sender; means responsive to the connection of said first-mentioned register-sender with said one private branch exchange trunk, to provide a signal to said first mentioned sub-set that dialling may commence; means responsive to the connection of the output of said second register-sender to said other private branch exchange to send to said second register-sender and signal conversion means, a signal to cause said second register-sender to send its received digital information to said other private branch exchange; meaNs responsive to the connection of said second registersender to a sub-set at the other private branch exchange, to connect the first-mentioned sub-set to the second-mentioned sub-set, bypassing the two register-senders and frequency conversion means.

Claim 16

The method of providing a two-way communication between the sub-sets of one private branch exchange and the sub-sets of another private branch exchange where each private branch exchange is associated with a local central office and connectible thereto by a trunk, and where each private branch exchange is designed so that the operator of a sub-set of one of the private branch exchanges may seize the trunk associated therewith; and where signals passing inwardly along said trunk to the associated private branch exchange may cause seizure of a sub-set, the method comprising the steps of: responsive to the seizure of such a trunk by a sub-set associated with the same private branch exchange; i. connecting the sub-set to a first storage for dialled digits where said sub-set and storage are connected to the same private branch exchange; ii. establishing a connection between the two local central offices; iii. responsive to the connection of said sub-set to storage, indicating to the sub-set that dialling may commence; iv. responsive to the establishment of said connection, extending said connection at the other central office, to second storage means for receiving and storing the digital information contained in such signals within the voice band; responsive to the storage of such dialed digits in said first storage, and the extension of said connection to the second storage means, sending the stored digits over said established connection to the other private branch exchange in the form of a signal having a frequency within the voice band; v. providing a connection for the output of said second storage means to the trunk associated with said other private branch exchange; vi. responsive to the provision of said last-mentioned connection and to the storage of at least some of said digital information in said second storage means, to supply signals containing digital information received, in said second storage means, to the trunk associated with said other private branch exchange; said signals being in a form to cause seizure by said trunk of the subset of said other private branch exchange.

Claim 17

The method of providing a two-way communication between the sub-sets of one private branch exchange and the sub-sets of another private branch exchange where each private branch exchange is associated with a local central office and connectible thereto by a trunk, and where each private branch exchange is designed so that the operator of a sub-set of one of the private branch exchanges may seize the trunk associated therewith; and where signals passing inwardly along said trunk to the associated private branch exchange may cause seizure of a sub-set, the method comprising the steps of: responsive to the seizure of such a trunk by a sub-set associated with the same private branch exchange; i. connecting the sub-set to a first storage for dialled digits where said sub-set and storage are connected to the same private branch exchange; ii. establishing a connection between the two local central offices; iii. responsive to the connection of said sub-set to storage, indicating to the sub-set that dialling may commence; iv. responsive to the establishment of said connection, extending said connection at the other central office, to second storage means for receiving and storing the digital information contained in such signals within the voice band; responsive to the storage of such dialed digits in said first storage, and the extension of said connection to the second storage means, sending the stored digits over said established connection to the other private branch exchange in the form of a signal having a frequency within the voice band; v. providing a connection for the output of said second storage means to the trunk associated with said other private branch exchange; vi. responsive to the provision of said last-mentioned connection and to the storage of at least some of said digital information in said second storage means, to supply signals containing digital information received, in said second storage means, to the trunk associated with said other private branch exchange; said signals being in a form to cause seizure by said trunk of the subset of said other private branch exchange.