Digital key telephone system and extension terminal device...

Telephonic communications – Multi-line or key substation system with selective switching... – Detail of hold circuitry

Reexamination Certificate

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Details

C379S142170, C379S164000, C379S265030

Reexamination Certificate

active

06408060

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a digital key telephone system provided in a company or an office.
BACKGROUND ART
A digital key telephone system comprises a main unit connected to a public network or a private branch exchange and a plurality of digital key telephones connected to the extension lines of the main unit. The digital key telephone has a plurality of push button type keys. When these keys are depressed, calling the public network or the private branch exchange, answering a call, and speech communication between digital key telephones are allowed. The main unit processes not only a control signal but also a speech communication signal as a digital signal and executes calling processing/call reception processing of each digital key telephone by a stored program control scheme and switching processing by a time switch of the digital speech communication signal.
As one of analog communication networks provided in U.S.A. recently, there is a communication network for providing a service called, e.g., “CLASS (Custom Local Area Signaling Service)”. The communication network for providing the CLASS service can superpose calling line identification information on a call signal and transmit it to the called subscriber.
When the digital key telephone system is connected to such a communication network, the main unit of the called digital key telephone system detects the first bell signal and then a modem signal. When calling line identification information is detected from the modem signal, the calling line identification information is transferred from the main unit to the called key telephone and displayed on the liquid crystal display device (LCD) of the key telephone. The user of the key telephone can recognize the calling line before off-hook by checking the calling line identification information displayed on the liquid crystal display device.
Conventionally, however, as the main function of the digital key telephone system using the calling line information notification service in the analog communication network such as the CLASS service, only the above-described calling line identification information display function is realized. Therefore, a demand has arisen for realization of a new and effective functional service using the CLASS service.
Another demand has arisen for expansion or realization of various support functions associated with wiring installation, a function of allowing a variety of call reception processing by adding a plurality of extension numbers to the digital key telephones, and a function of allowing a variety of communication processing operations using a personal computer combined with the digital key telephones.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a digital key telephone system capable of expanding or realizing various functions, e.g., realizing a more effective function using a calling line information notification service in an analog communication network.
In order to achieve the above object, according to the present invention, there is provided a digital key telephone system connected, through an office line, to an analog communication network having a function of transmitting a ringing signal including calling line identification information, accommodating a plurality of extension lines connected to extension terminals, and having a function of switching and connecting the office line to the plurality of extension lines or the extension lines to each other, comprising called party storage means storing information representing a correlation between a calling line and a called extension terminal in advance. By detecting the calling line identification information included in the ringing signal arriving from the analog communication network, the called extension terminal is determined on the basis of the detected calling line identification information and the information stored in the storage means, and call reception processing for the extension terminal is performed.
When called parties are registered in advance in correspondence with calling parties, an optimum extension terminal user can answer a call from a calling line. For example, a terminal for receiving and answering a call can be can be appropriately selected such that a person in charge directly answers a call from an important client, and a secretary answers calls from other clients.
In the present invention, when call reception processing is performed for the called extension terminal in response to arrival of the ringing signal, and the extension terminal does not answer the call, the calling line identification information detected from the ringing signal is stored in correspondence with the called extension terminal. When an operation of requesting call back is performed in the extension terminal which does not answer the call, call back processing is performed for the calling line on the basis of the stored calling line identification information. The calling line identification information is stored upon detecting restoration of the called office line during call reception processing.
If a call is received in the absence of the extension terminal user, the user can perform call back without the dialing operation only by performing the call back request operation. For this reason, the user operation associated with the call back operation can be simplified.
In the present invention, fault determination means using the calling line identification information is arranged. A detection result obtained when the calling line identification information included in the ringing signal is detected by the calling line identification information detection means is compared with that obtained when the calling line identification information is passed through the calling line identification information detection means together with the redundant data and detected by the fault determination means. With this operation, when a reception fault of the ringing signal is generated, determination processing is separately performed for each of the office line and the digital key telephone system.
With this arrangement, the fault occurrence position can be determined using the calling line identification information arriving from the analog communication network. As a result, separate fault determination can be relatively easily and properly performed, so a measure against the fault can be appropriately and quickly taken.
According to the present invention, there is also provided a digital key telephone system comprising an external communication interface with a plurality of serial communication ports for performing serial communication with external computer devices, and having a function of receiving function setting information sent from the external computer device through the external communication interface and setting a function of the digital key telephone system in accordance with the received function setting information, comprising function setting regulation means. While the function setting information is being received from an arbitrary one of the plurality of external computer devices, message information representing that function setting is disabled is transmitted to another external computer device, which is going to perform the function setting operation, and displayed, thereby regulating the function setting operation in another external computer device.
With this arrangement, the plurality of external computer devices are prevented from simultaneously performing function setting, so congestion of function setting processing from the plurality of external computer devices can be prevented.
When functions with different contents are set by the plurality of external computer devices, a function set by one of the external computer devices is preferentially operated in accordance with a predetermined rule. With this arrangement, even when a plurality of functions with inconsistent functions are set, the system can be prevented from erroneously operating.
In the present invention, the external communication interface compr

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