JPH0514413A - Private branch exchange - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a private branch exchange capable of simultaneously communicating with a plurality of communication partners without requiring a complicated operation by a terminal. [Configuration] A central control unit 107 sends a call request packet from a packet terminal 104 to an ISDN extension interface 109.
Also, it receives via the packet handler module 106 and analyzes the destination addresses to the plurality of communication partners coded in the call request packet. Then, a call request packet to each communication partner is created according to the analysis result, and IS is transmitted via the ISDN external line interface 102.
By transmitting to the DN network 101, simultaneous communication with a plurality of communication partners is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to private branch exchanges, especially ISDs.
The present invention relates to a private branch exchange that supports an N packet switching service and communicates with a plurality of communication partners.

[0002]

2. Description of the Related Art At present, circuit switching services and packet switching services are provided as data communication switching services in public networks. The former is DDX-C (circuit switching service), and the latter is DDX-P (first type). Switching services such as packet switching service), DDX-TP (second type packet switching service), and ISN-P (ISDN packet switching service) have been put into practical use. In particular, packet switching services are
It has the following features.

Since the communication network between different speed terminals has a store and exchange function, data communication can be performed even when the communication speed between terminals is different.

By exchanging communication procedures between terminals having different procedures, data communication can be performed even between terminals having different procedures.

By changing the packet multiplex communication destination information, it is possible to communicate with a plurality of parties using one physical line.

Detour route selection function Even if a relay line or the like fails during communication, another route in the network can be selected according to the destination information.

Information amount billing It is a billing method according to the amount of information (packet data).

Due to the above characteristics, recently, in conversational data communication such as personal computer communication and various reservation systems, the packet switching service is used regardless of terminals of different speeds and different procedures. Further, in the above-mentioned INS-P, the packet switching service can be used not only on the Bch, which is an information channel, but also on the Dch, which is a control channel.

One of the characteristics of this Dch packet communication is a terminal multiplexing function which cannot be used in the conventional packet switching service. This means that a maximum of 8 terminals can be connected on one physical line and the line can be used effectively.

It is also possible to perform packet communication with a plurality of parties such as three-party communication and circuit communication in circuit switching by using the multiplex communication function.

Further, as a calling operation in packet communication, there are a method of directly dialing the address (telephone number etc.) of the called party by the caller and a method of inputting the address from the terminal.

[0012]

However, in the above-mentioned conventional example, when packet communication is performed simultaneously with a plurality of parties such as three-party communication and conference communication using the packet switching service, for example, when a plurality of parties are used. When the number of participants increases, such as when playing a game, the following drawbacks occur in proportion to the number of participants.

Since a call setup procedure is required among all participants, the operation becomes complicated and the call setup procedure becomes complicated.

Since the same data is transmitted to each of a plurality of communication partners, the real-time property of the data is impaired.

In order to realize the above, a special function is required for the upper layer protocol of the terminal, and a general packet terminal cannot simultaneously communicate with a plurality of communication partners.

In order to realize the above, it is necessary to multiplex the line on the terminal side, a plurality of resources on the terminal side (extension side) are used, and the load of the packet handler for exchanging packet data increases. .

The present invention has been made to solve the above problems, and an object of the present invention is to provide a private branch exchange capable of simultaneously communicating with a plurality of communication partners without requiring a complicated operation by a terminal.

[0018]

In order to achieve the above object, the private branch exchange of the present invention has the following configuration.

That is, a plurality of terminals to be accommodated and ISDN
In a private branch exchange that supports an ISDN packet switching service for transmitting and receiving packet data to and from a network, an analyzing unit for analyzing destination addresses of a plurality of communication partners coded in a call request packet, and the analyzing unit The communication device further includes a creating unit that creates a call request packet for each communication partner according to the analysis result, and a transmitting unit that sends the call request packet created by the creating unit to each communication partner.

Further preferably, the creating means creates a call request packet for a party to which packet communication is not established among a plurality of communicating parties.

More preferably, each means is included in a storage exchange means for storing and exchanging the packet data.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of a private branch exchange in the embodiment. In the figure, 100 is a private branch exchange, 101 is an ISDN network, and 102 is an ISD.
ISDN external line interface connected to the N network 101,
103 is a communication path switch for connecting each interface,
104 and 105 are packet terminals, 106 is a packet handler module (hereinafter referred to as "PHM") which is a packet switching means, 107 is connection control of the communication path switch 103, and interfaces 102 and 109 and PHM 106. A central control unit (hereinafter referred to as “CC”) that transmits and receives control signals and data, and 108 is C
C107 and each interface 102, 109 and PHM
106 is a transmission path of control signals and data transmitted / received between the packet terminals 104 and 10;
5 ISDN extension interface (hereinafter,
"ISDN extension interface"), and 1
Reference numeral 10 is a storage unit including first and second storage areas.

FIG. 2 is a packet format showing a call request packet (CR) or an incoming call packet (CN) in this embodiment. As shown in the figure, a calling user address length, a called user address length 24, a called user address portion 25, and a calling user address portion 26 are defined in the user data portion of the packet.
Three-way communication or conference communication is performed in accordance with the data coded in. For example, the packet terminal 104 shown in FIG.
When performing three-way communication with another packet terminal via the ISDN network 101, a logical link is set up as shown in FIG. Here, the logical links between A-B, A-C, and B-C are the logical channel group numbers (LCGs) shown in FIG.
N: 4 bits) 21 and logical channel number (LCN: 8)
Bit) 22.

FIG. 4 is a packet format showing a data packet (DT), and the packet size differs depending on the contract conditions. Then, FIG. 5 is a packet format showing a recovery request packet (CQ) or a disconnection instruction packet (CI).

Next, with reference to the sequence diagram shown in FIG. 6 and the flowcharts shown in FIGS. 7 and 8, the packet level protocol (connection control procedure) for performing three-way communication in the exchange 100 in this embodiment will be described below. Explained.

First, CC1 of the exchange A100 shown in FIG.
The call setting process performed by 07 will be described. When the ISDN extension interface 109 receives the call request from the packet terminal 104, in order to transmit the packet data,
A data link (layer 2) is established with the ISDN extension interface 109 (step S101), and CC1
07 will be notified. On the other hand, the CC 107 determines whether the request is a Dch packet (step S10).
2) In the case of Dch packet, the transmission line 108 is used,
In the case of a Bch packet, the ISDN extension interface 109 and the communication path 103 are connected (step S10).
3). After that, when the ISDN extension interface 109 receives a CR (call request) packet from the packet terminal 104, the CR packet is transmitted to the PHM 106 through the transmission path 108 (Bch packet is the communication path 103) (step S104). Then, the PHM 106 transmits it to the CC 107 through the transmission path 108, and the CC 107 sends the CR
The destination address, facility, call user data, etc. coded in the packet are analyzed (step S105). Next, it is judged from the value of the called user address length 24 in the CR packet whether or not the three-party communication is performed (step S106). If the called address length 24 is not "0", the normal calling process is performed. Do (Step S
123). However, if the destination address length 24 is "0",
Recognized as three-party communication, call user in CR packet
The plurality of communication partner addresses coded in the data section 27 are stored in the second storage area of the storage section 110 (step S107).

Next, a CR packet is created for each of the plurality of communication partners coded in the call user data section 27, and the destination address of the destination is coded in the called user address section 25 of each CR packet. (Step S108). Then, it is judged from the destination address whether or not it is an extension call (step S109), and if it is an extension call, the CR packet is converted into a CN (incoming call) packet, and the logical channel group number (LCGN) and the logical channel number (LCGN) LCN) is set (step S110).
Then, the data link between the extension packet terminal 105 and the ISDN extension interface 109 is checked (step S1).
11), it is determined whether or not the link has been set (step S112). As a result, if not set, the ISDN extension interface 109 is instructed to set the data link and the data link is established (step S113). Next, the above-mentioned CN (incoming call) packet is transmitted to the PHM 106, and the PHM 106 sends the CN packet to the IS of the receiving side.
It is transmitted to the DN extension interface 109 (step S
114). Then, the ISDN extension interface 109
Transmits the CN packet to the packet terminal 105a (step S115), repeats the processing in steps S108 to S115 (step S116), and similarly ends the call setting processing for the packet terminal 105b.

On the other hand, if it is determined in step S109 that the call is not an extension call, the packet terminal 301 of the exchange B and the packet terminal of the exchange C shown in FIG. L contracted between
The CGN and LCN are coded in the CR packet as header information (step S117). And ISDN
The data link between the outside line interface 102 and the ISDN network 101 is checked (step S118), and it is determined whether the link has been set (step S119). If not set, the ISDN external line interface 102 is instructed to set the data link and the data link is established (step S120). Next, the CR packet described above is transmitted to the PHM 106, and the PHM 10
6 sends the CR packet to the ISDN external line interface 1
No. 02 (step S121). And ISD
The N external line interface 102 sends the CR packet to the IS
The call is set to the packet terminal 301 and the packet terminal 302 by transmitting the data to the DN network 101 (step S122) and repeating the above-described steps S108 to S122 twice (step S116).

Next, the ISDN external line interface 102.
When the two CC (call setup completion) packets are received from the ISDN network 101, the two CC packets are transferred to the PHM10.
6 to CC 107. And PHM1
06, the two X. 25 PLP (Packet Layer Protocol) is established. Next, one CC packet is sent from the CC 107 to the PHM 106, and the C
The PHM 106 that has received the C packet causes the X. 25 PLPs are established. Then, after the CC packet is transmitted from the PHM 106 to the ISDN extension interface 109 and further transmitted to the originating packet terminal 104, a data transfer phase is entered between the ISDN network 101 and the packet terminal 104.

Here, the data transfer phase in the three-party communication shown in FIG. 3 will be described. When the ISDN extension interface 109 receives the DT (data) packet from the packet terminal 104, the ISDN extension interface 109 transmits the DT packet to the PHM 106. Here, the PHM 106 analyzes the header information (the octets 1 to 3 shown in FIG. 4) of the DT packet,
The packet terminal 104 that has transmitted the DT packet recognizes that three-party communication is in progress. Then, the header information of the DT packet is changed to LCGN, LCN (on the logical link with the exchanges B, C) of the communication partner, and the DT packet is transmitted through the transmission line 1.
08 (call path 103 in the case of Bch packet) is used to transmit to the ISDN external line interface 102. PHM
106 repeats the above processing twice for the exchanges B and C, and D received by the ISDN external line interface 102.
The T packet is transmitted to the ISDN network 101. When the DT packet is received from another communication partner (301 of the exchange B, 302 of C), the PHM 106 changes the header information of the DT packet to that of the extension packet terminal 104 and transmits it.

The process of releasing the call of the corresponding logical channel will be described. First, when the ISDN extension interface 109 receives a CQ (recovery request) packet from the bucket terminal 104, the CQ packet is PHM-ized by using the transmission path 108 (Bch packet is the communication path 103).
To 106. The PHM 106 transmits the CQ packet received using the transmission path 108 to the CC 107, and C
The destination address, facility, call user data, etc. coded in the CQ packet by C107 (see FIG. 5) are analyzed. As a result, CC1
When the destination address length in the CQ packet is “0”, 07 recognizes that it is three-party communication, but if the destination address is not “0”, the normal disconnection process is performed.

Next, the CC 107 separately CQs the two communication partners (destination addresses) coded in the call user data section 27 in the CQ packet.
A packet is created, and the destination address of the destination is coded in the destination address part of each CQ packet. Then, it changes to the communication partner LCGN, LCN (on the logical link with B and C), and transmits the created CQ packet to the PHM 106 for the ISDN external line interface 102. As a result, the PHM 106 transmits the received CQ packet to the ISDN external line interface 102,
The DN external interface 102 sends the CQ packet to the IS
It is transmitted to the DN network 101.

The above process is repeated twice, and then IS
When the DN external line interface 102 receives two CF (disconnection confirmation) packets from the ISDN network 101, the IS
The DN external line interface 102 transmits two CF packets to the PHM 106. Then, the PHM 106 transmits the CF packet to the CC 107. Where CC1
In 07, when two CF packets corresponding to the two transmitted CQ packets are received, the CF packet is transmitted to the PHM 106 in order to transmit the CF packet to the packet terminal 104 that has activated the disconnection process. And
The PHM 106 sends the CF packet to the ISDN extension interface 109, and the ISDN extension interface 10
9 sends the CF packet to the packet terminal 104. Through the above processing, a plurality of communication partners and the packet terminal 104
Between X. 25PLP (L3) is released, and the disconnection process ends.

FIGS. 11 and 12 show the packet level protocol described above. FIG. 11 is a sequence diagram when the three-party communication shown in FIG. 3 is performed, and FIG. 12 is a sequence diagram when the three-party communication is performed between the packet terminals connected to the extension of the exchange 100. . still,
11 shows a packet between A and B shown in FIG. 3, or shows a packet between A and C.

Next, the packet level protocol of the called exchange 100 that performs the above-mentioned three-way communication will be described below with reference to the sequence diagram shown in FIG. 6 and the flow charts shown in FIGS. 9 and 10.

First, CC1 of the exchange B or C shown in FIG.
The call setting process performed by 07 will be described. When the ISDN external line interface 102 receives the call setup request (SETUP) message from the ISDN network 101 (step S201), the message is transmitted to the CC 107.
In the case of the Bch packet, the CC 107 connects the PHM 106 and the ISDN external line interface 102 via the communication path 103 (step S203). After that, when the ISDN external line interface 102 receives a CN (incoming call) packet from the ISDN network 101 (step S204), the CN packet is transmitted to the PHM 106 through the transmission path 108 (Bch packet is the communication path 103), and the PHM 106.
Transmits to CC 107 (step S205). CC1
07 analyzes the destination address, the facility, the call user data, etc. coded in the CN packet (step S206) and determines whether or not the communication is a three-party communication (step S207). Then, when the address of the communication partner is not coded in the call user data section 27 in the CN packet, normal incoming call processing is performed (step S216). However, if the address of the communication partner is coded, it is recognized that the communication is three-way communication, and the 10-second timer is set (step S208).

Next, the call user in the CN packet
The address of the communication partner coded in the address unit 27 is stored in the second storage area of the storage unit 110 (step S209). Then, the address of the communication partner that is continuing the packet communication stored in the first storage area of the storage unit 110 and the address of the communication partner that performs the three-way communication stored in the second storage area are compared. (Step S21
0). As a result, if packet communication is already in progress (the logical channel has been established between B and C in FIG. 3) (step S21)
1) Only the incoming call processing described below is performed.

Here, the ISDN extension interface 1
09, the data link between the extension packet terminal 301 is checked, and if not set, the ISDN extension interface 109
To instruct the setting of the data link and establish the data link. Next, the CN packet is transmitted to the PHM 106, the PHM 106 transmits the CN packet to the ISDN extension interface 109, and the ISDN extension interface 109 further transmits to the packet terminal 301. Then, when the ISDN extension interface 109 receives the CA (incoming call acceptance) packet from the packet terminal 301,
The CA packet is transmitted to PHM 106. As a result, the PHM 106 makes the X. Established 25 PLP,
The CA packet is transmitted to CC 107. Next, CC10
7 sends the CA packet to PHM 106, and PHM
106 is the X. 258 PLP is established and the CA packet is transmitted to the ISDN extension interface 109. Then, after the ISDN extension interface 109 transmits to the ISDN network 104, a data transfer phase between the packet terminal 301 and the ISDN network 101 is entered.

On the other hand, if the result of the determination in step S211 above is that packet communication is not in progress (the logical channel is being established between B and C), the other party of the incoming CN packet until the timer set in step S208 times out. The address is compared with the address of a communication partner for three-way communication (step S212). The result (step S2
13) If it is the corresponding communication partner, stop the timer (step S217). However, when the time-out occurs (step S214), a CR packet is created for the communication partner (destination address) for which the logical channel is not set. Then, the destination address of the transmission destination (that is, the packet terminal 302 of the exchange C in this example) is coded in the destination address portion of the CR packet. Next, LCGN and LCN contracted in advance with the ISDN network are coded in the CR packet as header information, and the data link between the ISDN external interface and the ISDN network is checked. If not set, the ISDN external line interface 102
To instruct the setting of the data link and establish the data link. Then, the created CR packet is used for PHM10.
6, the PHM 106 sends the CR packet to the ISD.
The ISDN external line interface 102 sends the CR packet to the ISDN external line interface 102.
It is transmitted to the network 101.

After that, the ISDN external line interface 10
2 receives the CC packet from the ISDN network 101,
The CC packet is transmitted to the PHM 106. PHM1
06 is two X. 25 PLP (packet layer protocol) is established, and the CC packet is transmitted to the CC 107. After that, the data transfer phase is entered between the ISDN network 101 and the PHM 106.

Next, the data transfer phase in the three-party communication will be described. First, in the exchange B or C, another communication partner (for example, the packet terminal 104 of the exchange A).
When the DT packet is received from the
The header information of the packet is changed to that of the packet terminal 301 or 302 of the exchange B or C and transmitted. Further, when the packet terminal 301 or 302 transmits a DT packet, when the DT packet is received, the header information of the DT packet (the part of octets 1 to 3 shown in FIG. 4) is analyzed, and the packet terminal 301 which has transmitted the DT packet. Or 3
02 determines whether or not three-party communication is in progress. And 3
In the case of person communication, the header information of the DT packet is changed to LCGN and LCN of the communication partner, and the DT packet is transmitted through the transmission line 10.
8 (call path 103 for Bch packet)
It is transmitted to the SDN external line interface 102. And
The DT packet received by the ISDN external line interface 102 is transmitted to the ISDN network 101 to perform data transfer.

Next, the cutting process will be described. First, the ISDN external line interface 102 of the exchange B or C is I
When a CI (disconnect instruction) packet is received from the DN network 101, the CI packet is transmitted to the PHM 106 using the transmission path 108 (Bch packet is the communication path 103), and the PHM
106 transmits the CI packet to CC 107. C
When the C107 receives the CI packet for the disconnection request from the communication partner of the three-party communication (for example, the extension terminal 104 of the exchange A), the C107 sets the 10-second timer. Here, when the address of the communication partner is not coded, normal disconnection processing is performed. However, when coded in the call user data section 27, the address of the communication partner is erased from the first storage area. And
The CI packet is transmitted to the PHM 106, and the PHM 106 transmits the CI packet to the ISDN extension interface 109.
The ISDN extension interface 109 to the CN.
The packet is transmitted to the extension packet terminal 301.

After that, the ISDN extension interface 10
When 9 receives a CF (disconnection confirmation) packet from the packet terminal 301 or 302, the transmission line 108 (Bch packet is the communication line 103) is used to PH the CF packet.
Send to M106. Here, the PHM 106 that received the CF packet is the X. 25 PLP (Layer 3) is released, and a CF packet is transmitted to CC 107. CC1
07 transmits the CF packet to the PHM 106, and the PHM 106 which has received the CF packet transmits the X.X. 25 PLP
(Logical channel with A) to release CF packet to I
It is transmitted to the SDN external line interface 102. And
The ISDN external line interface 102 sends the CF packet to the I
Transmission to the SDN network 101 completes the disconnection process.

On the other hand, the CC 107 monitors the disconnection from the communication partner performing the three-way communication until the set timer times out, and when the timer times out, the communication partner with which the logical channel has been established (switch C in this example). CQ packet is created for the extension terminal 302). Next, the destination address of the transmission destination is coded in the destination address part of the CQ packet, and the created CQ packet is converted to PHM10.
Send to 6. Then, the PHM 106 sends the CQ packet to the ISDN external line interface 102,
The DN external line interface 102 ISDs the CQ packet
It is transmitted to the N network 101. Then, when the ISDN external line interface 102 receives the CF packet from the ISDN network 101, the CF packet is transmitted to the PHM 106. Here, the PHM 106 that has received the CF packet is connected to the network side (extension terminal 302 of the exchange C) X. 25 PLP is released and a CF packet is transmitted to CC 107. CC107
Recognizes the disconnection with the communication partner (extension terminal 302 of C),
The disconnection process is completed.

13 and 14 are diagrams showing the packet level protocol described above. FIG. 13 is a sequence diagram of the exchange B shown in FIG. 3, and FIG. 14 is a sequence diagram of the exchange C. Incidentally, in the figure, indicates a packet between A and B shown in FIG. 3, a packet between A and C, and a packet between B and C, respectively.

As described above, according to this embodiment,
When performing packet communication simultaneously with a plurality of parties such as three party and conference communication using the packet switching service in the ISDN network and the private network, the central control unit (CC)
By analyzing the packet data received from the calling terminal and the ISDN network and establishing a plurality of communication partners (participants) and a plurality of packet links (layer 3), each participant has a plurality of communication partners. It is not necessary to carry out the call setup procedure of, and complicated operations are omitted.

Further, the packet terminal does not need to support the above-mentioned upper protocol, and the existing packet terminal can be effectively used. Further, it is not necessary to multiplex the line on the terminal side, resources on the terminal side (extension side) can be effectively used, and the load of the packet handler for exchanging packet data is also reduced.

[0049]

Other Embodiments Another embodiment of the present invention will be described below with reference to the drawings.

In the above-described embodiment, the central control unit (CC)
Analyzes packet data received from the originating terminal and ISDN network, establishes multiple packet links (Layer 3) with multiple communication partners, and uses the packet switching service in ISDN network and private network to perform three-party and conference communication. , Etc., packet communication is being carried out simultaneously with a plurality of parties,
It is also possible to give the packet handler module (PHM) a similar function.

FIGS. 15 and 16 are flow charts showing a call setting process performed by the PHM 106 in the packet level protocol (connection control procedure) for performing three-way communication in the exchange 100 shown in FIG. See also FIG.
7 and 18 are flowcharts showing a call setting process performed by the PHM 106 of the exchange B or C shown in FIG. Note that these processes are basically the same as the call setting process performed by the CC described above, and thus the description thereof is omitted here.

FIG. 19 is a sequence diagram when the three-way communication shown in FIG. 3 is performed, and FIG. 20 is a case where the three-way communication is performed between the packet terminals connected to the extension of the exchange A100. FIG. FIG. 19 shows a packet between A and B shown in FIG. 3 or a packet between A and C. Similarly,
FIG. 21 is a sequence diagram of the exchange B shown in FIG.
FIG. 22 is a sequence diagram of the exchange C. In the figure, a packet between A and B shown in FIG. 3, a packet between A and C, and a packet between B and C are shown.

According to another embodiment, the central control unit (CC)
By performing the call control processing performed in step 1 by the packet handler module, it is possible to reduce the CC load on the exchange.

In the above-described embodiment, the three-party communication has been described, but the present invention is not limited to this, and packet communication can be performed in the same manner as three or more communication partners.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0056]

As described above, according to the present invention,
It is possible to perform communication simultaneously with a plurality of communication partners without requiring complicated operations by the terminal, and it is possible to improve the convenience of the terminal and the exchange.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a private branch exchange in the present embodiment.

FIG. 2 X. It is a format diagram of a 25CR / CN packet.

FIG. 3 is a schematic diagram of a packet link in three-party communication.

FIG. It is a format diagram of a 25DT packet.

FIG. 5: X. It is a format diagram of a 25CQ / CI packet.

FIG. 6 is a sequence diagram in three-party communication.

[Figure 7]

FIG. 8 is a flowchart showing a control procedure on the calling side in the present embodiment.

[Figure 9]

FIG. 10 is a flowchart showing a control procedure on the called side in the present embodiment.

FIG. 11

FIG. 12 is a sequence diagram on the calling side in the present embodiment.

[Fig. 13]

FIG. 14 is a sequence diagram on the called side in the present embodiment.

FIG. 15

FIG. 16 is a flowchart showing a control procedure on the calling side in another embodiment.

FIG. 17

FIG. 18 is a flowchart showing a control procedure on the called side in another embodiment.

FIG. 19

FIG. 20 is a sequence diagram on the calling side in another embodiment.

FIG. 21

FIG. 22 is a sequence diagram on the called side in another embodiment.

[Explanation of symbols]

100 private branch exchange 101 public network 102 external line interface 103 Call path switch 104 Packet terminal (for outgoing) 105 Packet terminal (for incoming call) 106 packet handler module 107 Central control unit 108 transmission line 109 extension interface 110 storage

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04Q 3/58 101 9076-5K

Claims (3)

[Claims] 1. In a private branch exchange that supports an ISDN packet switching service for transmitting and receiving packet data between a plurality of accommodated terminals and an ISDN network, destination addresses of a plurality of communication partners coded in a call request packet. Analyzing means, creating means for creating a call request packet for each communication partner according to the analysis result by the analyzing means, and transmitting the call request packet created by the creating means to each communication partner A private branch exchange comprising: a transmission unit. 2. The private branch exchange according to claim 1, wherein the creating means creates a call request packet for a party to which packet communication is not established among a plurality of communication parties. 3. The private branch exchange according to claim 1, wherein each unit is included in a storage exchange unit that stores and exchanges the packet data.