Key telephone system providing selection of key or PBX operational modes
First Claim
1. A key telephone system which includes telephone station sets connected to a time division digital electronic switching system which handles information in the form of PCM codes having a processor controller for making connections between lines including internal lines connected to said station sets and outside trunk lines, which system provides both key and private branch exchange (PBX) modes of operation, said system comprising a plurality of keys on each of said station sets including a key (ITC) for selecting between said key and PBX modes, a key (OTG) for selecting access to the outside trunk lines, and a key (INC) for selecting access to a group of said plurality of station sets identified by a common pilot number, means for translating the status of said keys and PCM codes corresponding to the information to be transmitted by said station sets into multibit digital messages including first signalling bits representing the status of said keys, second signalling bits representing the status of telephone functions including hookswitch conditions, and PCM code bits, means in each of said sets for providing a plurality of channels respectively for signals corresponding to signalling messages consisting of said first signalling bits, signalling messages consisting of said second signalling bits, and messages consisting of said PCM codes, computer controller means in each of said station sets responsive to the messages in said signalling channels for controlling the operation of their respective telephone station set, line circuit means connected to said time division switching system and having means for transmitting and receiving said multibit digital messages from said telephone station sets, said line circuit means having signalling channels for messages consisting of said first and second signalling bits and a channel for said PCM codes, said line circuit means also having computer controller means responsive to the messages transmitted by said channels for transmitting messages to and receiving messages from said time division switching system and the processor thereof for operating said station sets in accordance with the status of said ITC, OTG and INC keys in key mode or in PBX mode.
1 Assignment
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Accused Products
Abstract
A key telephone system which provides both key and private branch exchange (PBX) operational modes utilizes a plurality of digital telephone station sets which communicate with line circuits connected to a time division multiplex (TDM) telephone switching system. A single pair of leads (tip and ring) connect each station set to the line circuits. The TDM switching system has a processor with an operating system which carries out the processes which provide for the selection of key and PBX features. The TDM switching system also provides access to trunk lines which connect the telephone station sets via the TDM switching system to other switching systems, such as the central office of the public utility telephone company. In the station sets and in the line circuits, there are provided channels for signalling data and for PCM data. The PCM data may be voice, codes, or digital data. Line interfaces are connected to the lead pairs from the station sets to line circuits and transmit and receive multibit digital messages containing signalling bits and PCM code bits. The signalling messages on one of the signalling channels represent the status of the keys, and control data for indicators (light emitting devices) and a display (LCD display on two lines) where alphanumeric characters as to call originations and the status of certain lines in the system may be displayed. These messages both signal and control the key features and the PBX features as and when selected by the keys; the signalling bits of the messages being compiled to provide the control data used in the station sets and transferred to the TDM switching system.
48 Citations
14 Claims
- 1. A key telephone system which includes telephone station sets connected to a time division digital electronic switching system which handles information in the form of PCM codes having a processor controller for making connections between lines including internal lines connected to said station sets and outside trunk lines, which system provides both key and private branch exchange (PBX) modes of operation, said system comprising a plurality of keys on each of said station sets including a key (ITC) for selecting between said key and PBX modes, a key (OTG) for selecting access to the outside trunk lines, and a key (INC) for selecting access to a group of said plurality of station sets identified by a common pilot number, means for translating the status of said keys and PCM codes corresponding to the information to be transmitted by said station sets into multibit digital messages including first signalling bits representing the status of said keys, second signalling bits representing the status of telephone functions including hookswitch conditions, and PCM code bits, means in each of said sets for providing a plurality of channels respectively for signals corresponding to signalling messages consisting of said first signalling bits, signalling messages consisting of said second signalling bits, and messages consisting of said PCM codes, computer controller means in each of said station sets responsive to the messages in said signalling channels for controlling the operation of their respective telephone station set, line circuit means connected to said time division switching system and having means for transmitting and receiving said multibit digital messages from said telephone station sets, said line circuit means having signalling channels for messages consisting of said first and second signalling bits and a channel for said PCM codes, said line circuit means also having computer controller means responsive to the messages transmitted by said channels for transmitting messages to and receiving messages from said time division switching system and the processor thereof for operating said station sets in accordance with the status of said ITC, OTG and INC keys in key mode or in PBX mode.
- 12. A key telephone system which comprises a key telephone set to which a station number and a key group number are assigned, said set having a first key (OTG) for selecting and originating a connection to any available one of a plurality of trunk circuits when operated, a second key (INC) for making the set available for connection to receive incoming calls directed to the key group number when operated, and a third key (ITC) for enabling said first and second keys to be operable when said third key is operated, and computer controlled switching means responsive to the state of said first, second and third keys for making multiple line and trunk connections to said set solely with said three keys.
Specification