JP2004274391A - Switching network system and telephone exchange equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently realize additional services such as display of the states of the extensions of other nodes corresponding to the line keys of an extension terminal, direct incoming calls to the extensions of other nodes, and transfer of the incoming calls while reducing the load on the signal transmission lines as much as possible. <P>SOLUTION: A request for acquisition of state information of extension terminals T21 to T2m, namely, a DSSR packet is transmitted from a key telephone master unit BT1 to a key telephone master unit BT2 through a LAN 1 at fixed time intervals. In the key telephone master unit BT1, registered contents of state information corresponding to extension terminals T21 to T2m, in a node information management table are updated on the basis of a DSSA packet and a DSSN packet which are sent from the key telephone master unit BT2 through the LAN 1 in response to transmission of the DSSR packet. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching network system that connects a plurality of telephone exchanges via, for example, a digital leased line, and executes processing related to an exchange service between the telephone exchanges, and the telephone exchange.
[0002]
[Prior art]
For example, in a company having a plurality of branches and offices, a network system installs a telephone exchange such as a PBX (Private Branch Exchange) or a key telephone main unit in each branch or office, and establishes a connection between these telephone exchanges. It is connected via a dedicated line. In this type of system, it is possible not only to perform inter-extension communication and outgoing / incoming transmission / reception of a public network etc. for each telephone exchange, but also to perform extension communication between different telephone exchanges and via different telephone exchanges. Local line transmission / reception can be performed.
[0003]
By the way, in recent years, with the advancement of the functions of the telephone exchange device, pressing a DSS (Direct Station Selection) key, which is a line key of an extension terminal accommodated during a call, causes the other node (another node) to be associated with the node. Implementation of a service that can display the state of an extension of a telephone exchange, receive a call directly to that extension, and perform call forwarding is also being considered. In this case, the DSS function in the own node is a function that has already been provided, and is extended so as to be realized via a network (for example, Patent Documents 1 to 3).
[0004]
However, in the above system, the dedicated line is occupied while the service is being executed, which affects, for example, transmission of a voice signal. In this case, the leased line has a B channel for transmitting a voice signal and a D channel for transmitting a control signal. In addition to a call control signal used for establishing and releasing a normal call, the state and registration information of an extension terminal are stored. It was necessary to include it in a conventional message or exchange it as another message between telephone exchanges.
Therefore, a plurality of telephone exchanges are connected by a dedicated line and connected by a LAN (Local Area Network) to transmit a signal requiring a real-time property such as a voice signal on the dedicated line and to transmit a control signal and the like in the LAN. A switching network system has been proposed in which transmission of a signal having a margin in real time is controlled independently and in parallel.
[0005]
[Patent Document 1]
JP-A-2002-101197.
[0006]
[Patent Document 2]
JP-A-2002-152224.
[0007]
[Patent Document 3]
JP-A-2000-138717.
[0008]
[Problems to be solved by the invention]
However, in the above network system, since it is necessary for the own node to know the state of the extension terminal of the other node corresponding to the DSS key, it is necessary to access the other node via the LAN, and the load on the LAN is correspondingly high. And inefficient. In particular, the larger the scale of the system becomes, the more remarkable it becomes, which is not preferable.
[0009]
Therefore, an object of the present invention is to provide additional services such as the display of the state of the extension of another node corresponding to the line key of the extension terminal, the direct incoming call to the extension of another node, the transfer of incoming calls, and the load on the signal transmission line as much as possible. It is an object of the present invention to provide a switching network system and a telephone switching apparatus for the switching network system, which can be realized efficiently by reducing it.
[0010]
[Means for Solving the Problems]
The present invention is configured as follows to achieve the above object.
(1) Two or more telephone exchanges accommodating at least one extension to which an extension terminal can be connected at the end, and a first telephone which connects a plurality of telephone exchanges and transmits a first signal requiring real-time performance. And a plurality of telephone exchanges connected independently of the first signal transmission path and a second signal for transmitting a second signal which does not require real-time performance as compared with the first signal transmission path. A signal transmission path, and each of the plurality of telephone exchanges is provided with a plurality of operation keys for specifying all extension terminals accommodated in the own device and an operation state of an extension terminal corresponding to each of the operation keys. Storage means for storing, in a recording medium, the first state information, an operation key for specifying each extension terminal accommodated in another device, and second state information indicating the operation state of the extension terminal corresponding to each of the operation keys. , State change detection means for detecting a change in the operation state of all extension terminals accommodated in the apparatus; and a first means for updating the storage content of the first state information in the recording medium based on a detection result by the state change detection means. Update request means for transmitting, via a second signal transmission path, a request for obtaining second state information as a second signal to a plurality of other telephone exchanges at predetermined time intervals; Receiving means for receiving the second state information transmitted from the other telephone exchange device via the second signal transmission path in response to the transmission of the request; and A second updating unit for updating the storage content of the second state information.
[0011]
According to the invention of (1), the data transmitted from the own telephone exchange to the other telephone exchange via the second signal transmission path every predetermined time is only a request for obtaining the second state information. The registered content of the second state information in the recording medium is updated based on the second state information of the other telephone exchange transmitted from the other telephone exchange via the second signal transmission path. Therefore, the second signal transmission path can be effectively used when shared by the telephone exchanges, whereby the load on the second signal transmission path can be reduced, and the second state information stored and managed on the recording medium can be reduced. Without having to access other telephone exchanges using, it is possible to perform appropriate additional service processing according to the state of each extension terminal of another telephone exchange with a simple procedure, and the processing of the telephone exchange accordingly. The load can be kept low.
[0012]
(2) The acquisition request sending means sends the first state information as a second signal via the second signal transmission line at a different transmission timing for each telephone exchange.
According to the invention of (2), by setting the transmission timing for each telephone exchange, a plurality of pieces of second state information relating to different telephone exchanges do not concentrate in the same time zone. The load on the second signal transmission path and the processing load on the telephone exchange can be further reduced.
[0013]
(3) The second signal transmitted through the second signal transmission path is a signal defined by UDP (User Datagram Protocol).
According to the invention of (3), there is no need to perform complicated processing such as retransmission and flow control for improving the reliability of communication unlike TCP / IP, so that the load on the second signal transmission path is reduced. In addition, the processing load on the telephone exchange can be reduced.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a switching network system according to the present invention.
As shown in the figure, this system includes key telephone main units BT1 to BT4, and a digital leased line PN (PCH) having a communication channel (Bch) and a control channel (Dch) between the key telephone main units BT1 to BT4. PN1-2, PN1-3, PN2-3, PN3-4). These key telephone telephone devices BT1 to BT4 accommodate extension terminals T11 to T1i, T21 to T2m, T31, and T41 to T4k via extensions. The key telephone main units BT1 and BT4 are connected to public networks NW1 and NW2 via a central office L.
The key telephone main devices BT1 to BT4 are connected to a LAN (Local Area Network) 1.
[0015]
Next, a specific configuration of the key telephone main units BT1 to BT4 will be described in detail with reference to FIG. Here, the key telephone main unit BT1 will be described as a representative.
The key telephone unit BT1 includes a central office interface unit 11, an extension interface unit 12, a digital leased line interface unit 13, and a control unit 14, which are interconnected via a voice bus 15 and a control bus 16. Have been.
[0016]
The office line L is connected to the office line interface unit 11 as needed. The office line interface unit 11 performs an office line interface operation on the connected office line L. The office line interface operation includes transmission of an outgoing signal to the public network NW and detection of an incoming signal from the public network NW. The office line interface unit 11 exchanges various control information related to the office line interface operation with the control unit 14 via the control bus 16.
[0017]
A plurality of extensions are connected to the extension interface unit 12 as needed. The extension interface unit 12 performs an extension interface operation for the connected extension. The extension interface operation includes transmitting an incoming signal to each extension and detecting an outgoing signal from each extension. The extension interface unit 12 exchanges various control information related to the extension interface operation with the control unit 14 via the control bus 16.
[0018]
The digital leased line interface PN is connected to the digital leased line interface PN as required. The digital leased line interface unit 13 performs a digital leased line interface operation for the connected digital leased line PN. The operation of the digital leased line interface includes transmitting an outgoing signal to the digital leased line PN and detecting an incoming signal from the digital leased line PN. The digital leased line interface unit 13 exchanges various control information related to the digital leased line interface operation with the control unit 14 via the control bus 16.
[0019]
The control unit 14 includes a sub control unit 141, a main control unit 142, a storage unit 143, a time switch 144, and a LAN interface unit (LAN I / F) 145. Among them, the sub control unit 141, the main control unit 142, the storage unit 143, and the LAN interface unit 145 are mutually connected via the microcomputer bus 146. The time switch 144 is directly connected to the main control unit 142. Further, a timer 147 is connected to the main control unit 142.
[0020]
The sub-control unit 141 exchanges control information between the control bus 16 and the microcomputer bus 146. The main control unit 142 executes the entire control in the key telephone main device BT1 based on the control program and the control data stored in the storage unit 143. The storage unit 143 stores a control program and control data for the main control unit 142 to execute a process, and particularly stores various data at the time of an exchange operation.
[0021]
The time switch 144 controls the channel of the digital signal transmitted through the audio bus 15 between the office line interface unit 11, the extension interface unit 12, and the digital leased line interface unit 13 according to the instruction of the main control unit 142. Perform an exchange.
The LAN interface unit 145 performs an interface process related to transfer of control information between the microcomputer bus 146 and the LAN 1.
[0022]
By the way, in this embodiment, the storage unit 143 is provided with a node information management table 1431. As shown in FIG. 3, the node information management table 1431 includes, in addition to the extension number information of the extension terminals T11 to T1i connected to the own device, T21 to T2m connected to the key telephone main devices BT2 to BT4, respectively. The extension number of T31, T41 to T4k, the state of extension terminals T11 to T1i, T21 to T2m, T31, T41 to T4k, and data representing the correspondence between the extension terminal of the DSS key and the key information group are stored. .
[0023]
In addition, the main control unit 142 includes a state change detection unit 1421, a local information update unit 1422, a transmission unit 1423, a reception unit 1424, and another node information update unit 1425. State change detection section 1421 detects a change in the operation state of all extension terminals T11 to T1i accommodated in key telephone apparatus BT1.
[0024]
The local information updating unit 1422, based on the detection result of the state change detecting unit 1421, changes the operating state of each of the extension terminals T11 to T1i, and displays the changed extension terminal in the node information management table 1431. The status information corresponding to T11 to T1i is updated from "free" to "busy" or from "busy" to "vacant". Update from “empty” to “ringing”, from “ringing” to “empty”, and from “ringing” to “talking”.
[0025]
The transmission unit 1423 sends a request for obtaining local information indicating the state of each of the extension terminals T21 to T2m, T31, T41 to T4k to the other key telephone main devices BT2 to BT4 at the time intervals set in the timer 147 by the UDP protocol. , And transmits this DSSR packet via LAN1.
[0026]
Receiving section 1424 receives local information, that is, DSSA packets and DSSN packets transmitted from other key telephone main devices BT2 to BT4 via LAN 1 in response to the acquisition request.
The other node information updating unit 1425 stores the storage contents of the state information of each of the extension terminals T21 to T2m, T31, T41 to T4k in the node information management table 1431 based on the DSSA packet and the DSSN packet received by the receiving unit 1424. To update.
[0027]
Next, the operation of the system configured as described above will be described.
FIG. 4 is a sequence diagram showing an operation of transmitting and receiving information between the key telephone apparatus BT1 and the key telephone apparatus BT2, for example.
When the time set in the timer 147 is counted, the key telephone main unit BT1 creates a list of extension terminals T21 to T2m of the key telephone main unit BT2, and based on this list, as shown in FIG. A DSSR packet in a UDP format including a network DN of the extension terminal (DN (extension telephone number of the extension terminal including the node ID)) associated with the node ID of the key telephone apparatus (node) accommodating the DSS key is created. The node ID “11” indicates the key telephone main unit BT1, and the node ID “13” indicates the key telephone main unit BT3. Thereafter, the key telephone main unit BT1 transmits a DSSR packet to the key telephone main unit BT2 via the LAN1.
[0028]
The key telephone apparatus BT2 that has received the DSSR packet sets the extension terminal to be associated with the network DN and the requested node ID in the node information management table 1431 as shown in FIG.
[0029]
In the key telephone main unit BT2, each time the extension terminals T21 to T2m start the call processing, the state of each of the extension terminals T21 to T2m is recorded in the node information management table 1431 as shown in FIG. A list representing the correspondence between the terminals T21 to T2m and the respective states is created, and a DSSA packet as shown in FIG. 8 is created based on this list. This DSSA packet is a response packet to the DSSR packet. Thereafter, a DSSA packet is transmitted to the key telephone apparatus BT1 via the LAN1.
[0030]
The key telephone apparatus BT1 that has received the DSSA packet updates the extension status for each network DN associated with the node information management table 1431 and displays the extension status on the LED of the associated DSS key.
[0031]
Further, in the key telephone main unit BT2, each time the extension terminals T21 to T2m associated as an extension status notification other than the DSSA packet develop a call or service, the state of the extension terminals T21 to T2m is recorded in the node information management table 1431. Then, each time there is a change, a DSSN packet is created as shown in FIG. Thereafter, the key telephone apparatus BT2 transmits a DSSN packet to the key telephone apparatus BT1 via the LAN1.
[0032]
The key telephone apparatus BT1 that has received the DSSN packet updates the extension state for each network DN associated with the node information management table 1431 and displays the extension state on the LED of the associated DSS key.
In the above processing, the same processing procedure is executed for the key telephone main unit BT3 at a different time from that of the key telephone main unit BT2, and the key telephone main unit BT2 and BT3 are also connected to the key telephone main unit BT4. Similar processing procedures are executed at different times.
[0033]
FIG. 10 is a flowchart showing the operation procedure of the key telephone main unit BT1 and its contents.
The main control unit 142 of the key telephone main unit BT1 monitors the operation state of each of the extension terminals T11 to T1i, and when there is a state change, the changed extension terminal T11 to T1i in the node information management table 1431. Update the status information of
[0034]
Subsequently, when the timer 147 measures the local information acquisition request time for the other key telephone main device BT2, the main control unit 142 determines whether or not there is state information on the other node in the node information management table 1431. (Step ST10a). Here, if there is no state information related to another node (No), the main control unit 142 ends the processing as it is, and if there is state information related to another node (Yes), for example, an extension terminal is requested to request acquisition of state information. A list of T21 to T2m is created, a DSSR packet is created based on this list (step ST10b), and this DSSR packet is transmitted to the key telephone apparatus BT2 (step ST10c).
[0035]
Subsequently, the main control unit 142 determines whether or not there is state information on the other node in the node information management table 1431 in addition to the key telephone main device BT2 (step ST10d). Until there is no more, the processes of steps ST10b to ST10d are repeatedly executed. Then, when there is no more status information on the other node, the above process is terminated.
[0036]
In response, the key telephone main unit BT2 starts the control processing shown in FIG.
Upon receiving the DSSR packet, the main control unit 142 of the key telephone main unit BT2 refers to the node information management table 1431 and creates a DSSA packet including the current state information of each of the extension terminals T21 to T2m. The DSSA packet is transmitted to the requesting key telephone main unit BT1 via the LAN1.
[0037]
Subsequently, the main control unit 142 of the key telephone main device BT2 monitors the operation state of the corresponding extension terminals T21 to T2m (step ST11a), and determines whether there is a state change (step ST11b). Then, when there is a state change (Yes), the main control unit 142 updates the state information of the extension terminals T21 to T2m in the node information management table 1431 where the change has occurred (step ST11c).
[0038]
Subsequently, the main control unit 142 determines whether or not it is necessary to notify the other nodes, that is, the key telephone telephone apparatus BT1 as the request source, of the state information of the extensions T21 to T2m (step ST11d). When it is necessary (Yes), a DSSN packet including the status information of each of the extensions T21 to T2m is created (step ST11e), and this DSSN packet is transmitted to the requesting key telephone main device BT1 via the LAN1. (Step ST11f).
[0039]
On the other hand, the key telephone main unit BT1 starts the control processing shown in FIG.
The main control unit 142 of the key telephone main unit BT1 determines whether a DSSA packet or a DSSN packet has been received from the key telephone main unit BT2 (step ST12a), and determines that a DSSA packet has been received (step ST12a). Yes), the DSSA packet is received (step ST12b), and based on the state information of each of the extension terminals T21 to T2m included in this DSSA packet, the state information of each of the corresponding extension terminals T21 to T2m in the node information management table 1431 is changed. Update (step ST12c).
[0040]
On the other hand, if it is determined in step ST12a that a DSSN packet has been received (No), the main control unit 142 receives the DSSN packet (step ST12d), and based on the state information of each of the extension terminals T21 to T2m included in the DSSN packet. Then, the status information of the corresponding extension terminals T21 to T2m in the node information management table 1431 is updated (step ST12e).
Note that the same procedure as the above-described processing procedure is executed at different timings for the key telephone main devices BT3 and BT4.
[0041]
Thus, as shown in FIG. 13, the user of the extension terminal T45 (extension number 501) of the key telephone main unit BT4 looks at the LED of the DSS key corresponding to the extension terminal T42 (extension number 202) and operates the extension terminal T42. , And the operating state of the extension terminal T21 can be known by looking at the LED of the DSS key corresponding to the extension terminal T21 (extension number 21200).
[0042]
Further, the user of the extension terminal T46 (extension number 502) of the key telephone main unit BT4 can know the operation state of the extension terminal T42 by looking at the LED of the DSS key corresponding to the extension terminal T42 (extension number 202). The operation state of the extension terminal T21 can be known by looking at the LED of the DSS key corresponding to the extension terminal T21 (extension number 21200) of the key telephone main unit BT2, and the extension terminal T11 (extension number 10200) of the key telephone main unit BT1 can be known. The operation state of the extension terminal T11 can be known by looking at the LED of the DSS key corresponding to ()).
[0043]
As described above, in the above-described embodiment, the data transmitted from the key telephone main unit BT1 to the key telephone main unit BT2 via the LAN 1 at regular time intervals is a request for obtaining the state information of the extension terminals T21 to T2m, that is, only the DSSR packet. In the key telephone main unit BT1, registration of state information corresponding to the extension terminals T21 to T2m in the node information management table 143 based on the DSSA packet and the DSSN packet transmitted from the key telephone main unit BT2 via the LAN1. The content is updated.
[0044]
Therefore, the LAN1 can be effectively used when shared by the key telephone main units BT1 to BT4, whereby the load on the LAN1 can be reduced. In addition, the key telephone main unit BT1 stores and manages the information stored in the node information management table 143. Each of the extension terminals T21 of the other key telephone telephone apparatuses BT2 to BT4 by a simple procedure without accessing the other key telephone telephone apparatuses BT2 to BT4 using the state information on the extension terminals T21 to T2m, T31, T41 to T4k.付 加 T2m, T31, and T41 to T4k, so that appropriate additional service processing can be performed, and the processing load on the key telephone main unit BT1 can be reduced accordingly.
[0045]
Further, according to the above embodiment, by setting the transmission timing of the DSSR packet for each of the key telephone main devices BT1 to BT4, a plurality of key telephone main devices BT2 to BT4 related to different key telephone main devices BT2 to BT4 are set in the key telephone main device BT1. DSSA packets and DSSN packets are prevented from arriving at the same time in a concentrated manner, thereby further reducing the load on the LAN 1 and the processing load on the key telephone equipment BT1 to BT4.
[0046]
Furthermore, according to the above-described embodiment, transmission and reception of packets between the key telephone apparatuses BT1 to BT4 are performed in accordance with the UDP protocol, thereby improving the reliability of communication, for example, as in TCP / IP (Transmission Control Protocol / Internet Protocol). There is no need to perform complicated processing such as retransmission or flow control to increase the load, thereby reducing the load on the LAN 1 and the processing load on the key telephone main units BT1 to BT4.
[0047]
Note that the present invention is not limited to the above embodiment. In the above embodiment, the example in which the key telephone main units are connected by the digital dedicated line and the LAN has been described. However, without being limited to this, the key telephone main units are connected by a transmission path for transmitting a signal requiring real-time property and a transmission path for transmitting a signal having a margin in real-time property. There may be.
[0048]
Further, in the above-described embodiment, the network system in which the key telephone main units are connected by the digital leased line has been described as an example. However, the present invention can be similarly applied to, for example, an IP telephone system.
[0049]
In addition, the system configuration, the type and configuration of the key telephone main unit, the type of extension terminal, the information transmission / reception procedure, the control procedure of each control and the contents thereof are variously modified without departing from the gist of the present invention. Can be implemented.
[0050]
【The invention's effect】
As described in detail above, according to the present invention, additional services such as the display of the state of the extension of another node corresponding to the line key of the extension terminal, the direct reception to the extension of another node, and the transfer of a call can be transmitted through the signal transmission path. A switching network system and a telephone switching apparatus for the switching network system, which can reduce the load as much as possible as much as possible and can be realized efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a switching network system according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a specific configuration of the key telephone main devices BT1 to BT4 shown in FIG.
FIG. 3 is a diagram showing an example of storage contents of a node information management table shown in FIG. 2;
FIG. 4 is an exemplary sequence diagram showing an operation of transmitting and receiving information between the key telephone main devices in the embodiment.
FIG. 5 is a structural diagram of a DSSR packet.
FIG. 6 is a diagram showing a correspondence relationship between an extension terminal related to a network DN and a requested node ID in a node information management table.
FIG. 7 is a diagram showing an example of state information of an extension terminal in a node information management table.
FIG. 8 is a structural diagram of a DSSA packet.
FIG. 9 is a structural diagram of a DSSN packet.
FIG. 10 is a flowchart showing an operation procedure and contents of the key telephone main unit when transmitting a DSSR packet.
FIG. 11 is a flowchart showing an operation procedure and contents of the key telephone main unit when transmitting a DSSA packet and a DSSN packet.
FIG. 12 is a flowchart showing an operation procedure of the key telephone main unit when a DSSA packet and a DSSN packet are received, and the contents thereof.
FIG. 13 is an exemplary sequence diagram illustrating a correspondence between a DSS key and an extension terminal in the extension terminal according to the embodiment;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... LAN (Local Area Network), 11 ... Office line interface unit, 12 ... Extension interface unit, 13 ... Digital leased line interface unit, 14 ... Control unit, 15 ... Audio bus, 16 ... Control bus, 141 ... Sub control unit .. 142 main control unit, 143 storage unit, 144 time switch, 145 LAN interface unit, 146 microcomputer bus, 147 timer, 1421 state change detection unit, 1422 local information update unit, 1423 transmission unit .., 1424... Receiving unit, 1425... Other node information updating unit, 1431... Node information management table, BT 1 to BT 4, key telephone main unit BT, PN. ... Extension terminal, L ... Office line, NW1, NW ... public network.

Claims (5)

A first signal transmission for connecting between two or more telephone exchanges accommodating at least one extension capable of connecting an extension terminal to an end and the plurality of telephone exchanges, and transmitting a first signal requiring real-time performance Road and
A second signal transmission path that connects the plurality of telephone exchanges independently of the first signal transmission path and transmits a second signal that does not require real-time performance as compared with the first signal transmission path; With
Each of the plurality of telephone exchanges,
A plurality of operation keys for designating at least a part of all extension terminals accommodated in the own device, first state information indicating an operation state of the extension terminal corresponding to each of these operation keys, Storage means for storing, in a recording medium, an operation key for designating at least a part of the extension terminal and second state information indicating an operation state of the extension terminal corresponding to each of the operation keys;
State change detecting means for detecting a change in the operation state of all extension terminals accommodated in the own device,
First update means for updating the storage content of the first state information in the recording medium based on a detection result by the state change detection means;
Acquisition request sending means for sending an acquisition request for the second state information to the plurality of other telephone exchanges at predetermined time intervals as the second signal via the second signal transmission path;
Receiving means for receiving second state information sent from another telephone exchange via the second signal transmission path in response to sending the acquisition request;
An exchange network system comprising: a second updating unit that updates the storage content of the second state information in the recording medium based on a result of the reception by the receiving unit. 2. The switching network according to claim 1, wherein the acquisition request sending unit transmits the acquisition request as a second signal via the second signal transmission line at a different transmission timing for each telephone exchange. system. 2. The switching network system according to claim 1, wherein the second signal transmitted through the second signal transmission path is a signal defined by UDP (User Datagram Protocol). The first signal transmission path is a digital dedicated line for transmitting an audio signal,
2. The switching network system according to claim 1, wherein said second signal transmission path is a local area network for transmitting a control signal. A telephone exchange used in the exchange network system according to claim 1,
A plurality of operation keys for designating at least a part of all extension terminals accommodated in the own device, first state information indicating an operation state of the extension terminal corresponding to each of these operation keys, Storage means for storing, in a recording medium, an operation key for designating at least a part of the extension terminal and second state information indicating an operation state of the extension terminal corresponding to each of the operation keys;
State change detecting means for detecting a change in the operation state of all extension terminals accommodated in the own device,
First update means for updating the storage content of the first state information in the recording medium based on a detection result by the state change detection means;
Acquisition request sending means for sending an acquisition request for the second state information to the plurality of other telephone exchanges at predetermined time intervals as the second signal via the second signal transmission path;
Receiving means for receiving second state information sent from another telephone exchange via the second signal transmission path in response to sending the acquisition request;
A telephone exchange device comprising: a second updating unit that updates a storage content of the second state information in the recording medium based on a reception result by the receiving unit.

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