JP2004312440A - Private branch exchange system for performing inter-system connection by ip, and its system information transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To conduct IP connection at comparatively low cost on the inter-system connection of an extension call in a plurality of PBX (Private Branch Exchange) systems without providing an IP (Internet Protocol) gateway separately. <P>SOLUTION: The system comprises a plurality of PBX systems 1 connected each other through a LAN (Local Area Network) 4, and a plurality of telephone devices 11 under the PBX systems 1. Each of the PBX systems 1 comprises a CPU 12, a storage unit 13, a telephone device interface 14, and a LAN controller 15. The CPU 12 executes call control for the plurality of telephone devices 11 between the own and the other PBX systems 1 through the LAN 4 according to the H.323 call control protocol. The CPU 12 establishes TCP (Transmission Control Protocol) connection between the own and the other PBX systems 1 according to TCP. After originating a call by the H.323 call control during call origination by one of the telephone devices 11, the CPU 12 transmits predetermined system information to other PBX systems 1 by TCP connection established separately. After terminating a call by the H.323 call control during call termination by one of the telephone devices 11, the CPU 12 transmits predetermined system information to the other PBX systems 1 by TCP connection established separately. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a private branch exchange (PBX) system that performs intersystem connection by IP (Internet Protocol) and a system information transmission method thereof. The PBX system is connected by a LAN, and the intersystem connection interface by IP is used. H. The present invention relates to a PBX system using the H.323 protocol.
[0002]
[Prior art]
PBX is a system that is installed in offices of companies, factories, government offices, schools, etc., and exchanges extension telephones and exchanges connections between extension telephones and external general telephones. It can be provided.
[0003]
Further, in large-scale enterprises having a plurality of bases such as a head office, a fulcrum, and a sales office, a PBX system is installed at each base, and each PBX system is connected by an ISDN (Integrated Service Information Network) network, and the own PBX system. An extension call from an extension telephone connected to the extension telephone connected to another PBX system is performed via the ISDN network. That is, inter-system connection in the case where an extension call is made between a plurality of such PBX systems has been realized by an ISDN interface.
[0004]
In general, the ISDN communication protocol group is also collectively referred to as an I series interface (ITU-T recommendation), and is divided into a user information channel (B channel) and a control channel (D channel) according to each communication mode. (Open System Interconnection) Basic interface / primary group interface (ISDN layer 1 protocol) corresponding to the physical layer of the reference model, X. 25 data link layer (LAPB: Link Access Procedure Balanced) and LAPD (Link Access Procedure on the D-channel) (ISDN layer 2 protocol), X. 25 network layers and information channel call control procedures (ISDN layer 3 protocol) are defined.
[0005]
On the other hand, recently, IP phones that perform voice calls over IP networks (IP networks) based on IP (Internet Protocol) corresponding to the network layer of the OSI reference model used in the Internet have become widespread, and their quality improvement and broadband Along with the price reduction of lines, there are many cases in which an IP telephone network is constructed by a large-scale company or the like for the purpose of reducing extension telephone charges (for example, see Non-Patent Document 1).
[0006]
When such an IP phone network is applied to an extension call between own and other PBX systems located at multiple locations such as the head office and sales offices, an outside line call with a general telephone is made via a public network, and other PBX systems It is necessary to make an extension call with an extension telephone via the IP network. That is, since it is necessary to make an IP connection between the own and other PBX systems, an IP gateway is installed for each PBX system to convert protocols between ISDN and IP. In this case, the voice data from the extension telephone configured according to the ISDN protocol by the own PBX system is converted into an IP packet by the protocol conversion by the IP gateway, and the IP routing by the router based on the destination IP address of the IP header. Is sent to the router on the other PBX system side via the IP network, is returned from the IP packet to the ISDN voice data by the IP gateway, and is sent to the extension telephone of the other PBX system. As a result, an extension call between the own and other PBX systems is performed.
[0007]
[Non-Patent Document 1]
Yoneda Shinbun, “The latest network technology that can be understood by IP phone”, Shosuisha Co., Ltd., February 2003, p190
[0008]
[Problems to be solved by the invention]
However, since one IP gateway is required for each PBX system to be connected when performing IP connection in a PBX system using an ISDN interface, the system becomes relatively expensive, and in addition, equipment Due to the compatibility with other devices, devices that operate abnormally are suitable, which may cause unexpected problems.
[0009]
The present invention has been made in consideration of such a conventional situation. In the inter-system connection of extension calls in a plurality of PBX systems, the IP connection can be performed relatively inexpensively without providing an IP gateway separately. The purpose is to avoid a situation in which an abnormal operation occurs due to the compatibility of.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an IP gateway function is built in a PBX system, the PBX system is connected to a LAN such as Ethernet (registered trademark), and the other PBX system is connected via an IP network via a router. The structure which can implement | achieve the connection between systems in is provided.
[0011]
In the above configuration, H.264 is used as an interface protocol for connection between systems. Using the communication protocol of H.323 (ITU-T recommendation), the same function as a single system is realized between connected systems, and various information in the system is transferred to the transport layer of the separately generated OSI reference model. In a TCP connection according to the corresponding TCP (Transmission Control Protocol), Notification is made by a system different from that of H.323.
[0012]
That is, if the IP interface module that can be installed in the own system can perform the same as ISDN, it is not necessary to provide an IP gateway separately for IP connection, and the above-mentioned problems relating to this can be solved.
[0013]
However, in ISDN, system information such as a change in the state of each terminal (extension telephone) that is not directly related to a call is Q.Q. H. 931 (ITU-T recommendation) communication protocol is irregularly notified. According to the H.323 protocol, it is impossible to notify such system information irregularly.
[0014]
For this reason, in the present invention, H.264. We focused on establishing a TCP connection independently of the H.323 protocol and notifying system information such as the state change of each terminal that is not directly related to the call irregularly. As a result, even when no call is generated, information in the system such as terminal status information and notification of various settings can be exchanged.
[0015]
In addition, since the TCP connection has the properties of both a server and a client, it is possible to request connection establishment from both directions without worrying about whether the server and the client are different. According to this, if there is a message transmission request from a state where the connection is not established, it is possible to issue a connection request to the other port, and it is possible to accept if there is a connection request at the own port. . In other words, every system has the properties of a server and a client, and if it is a TCP connection, either one of the two systems will be a server and the other will be a client. Can connect without being conscious.
[0016]
In this way, connection between PBX systems and transmission of system information by IP becomes possible.
[0017]
The present invention has been completed based on such an idea.
[0018]
That is, a private branch exchange system that performs intersystem connection by IP according to the present invention includes a plurality of PBXs (Private Branches) that are communicably connected via a LAN (Local Area Network) according to an IP (Internet Protocol) communication protocol. eXchange) system and a plurality of telephones mounted on each PBX system.
[0019]
In the above configuration, the plurality of PBX systems include a LAN controller connected to the LAN, and an H.264 network. H.323, which executes call control for the plurality of telephones via the LAN between its own and other PBX systems according to the H.323 call control protocol. 323 call control means, TCP connection establishment means for establishing a TCP connection via the LAN between the own and other PBX systems according to a TCP (Transmission Control Protocol) communication protocol, and when the telephone of the own PBX system makes a call H. When making a call by sending predetermined system information from the LAN controller to the other PBX system via the LAN after the call is made by the call control by the H.323 call control means and the TCP connection established by the TCP connection establishment means. At the time of an incoming call of the transmission means and the telephone of the own PBX system. When an incoming call is received by call control by the H.323 call control means, and then predetermined system information is transmitted from the LAN controller to the other PBX system via the LAN by the TCP connection established by the TCP connection establishment means. And a transmission means.
[0020]
The predetermined system information preferably includes system information not directly related to the call of the own PBX system and information on a telephone state that needs to be notified to the other PBX system.
[0021]
The calling means transmitting means determines whether the dialed extension number is that of the local PBX system telephone or the other PBX system telephone when the local PBX system telephone makes a call; When it is determined that the extension number is that of the telephone of the other PBX system, there is provided means for obtaining an IP address corresponding to the extension number and means for sending a call setting connection request message to the IP address. May be.
[0022]
In addition, a system information transmission method according to the present invention includes a plurality of PBX (Private Branch exchange) systems that are communicably connected via a LAN (Local Area Network) according to an IP (Internet Protocol) communication protocol, A plurality of telephones mounted on the PBX system are used.
[0023]
In the above configuration, the plurality of PBXs may be H.264. H. 323 executes call control for the telephone via the LAN between its own and other PBX systems according to the H.323 call control protocol. A H.323 call control step, a TCP connection establishment step for establishing a TCP connection via the LAN between the own and other PBX systems in accordance with a TCP (Transmission Control Protocol) communication protocol, and when the telephone in the own PBX system makes a call, H. A call transmission step of transmitting predetermined system information to the other PBX system via the LAN after a call is made by call control in the H.323 call control step, and a TCP connection established by the TCP connection establishment step; When the telephone in the PBX system is called, the H. An incoming call transmission step of transmitting predetermined system information to the other PBX system via the LAN after the incoming call is made by the call control in the H.323 call control step and the TCP connection established in the TCP connection establishment step. It is characterized by having.
[0024]
Preferably, the predetermined system information includes system information not directly related to a call of the own PBX system and information on a telephone state that needs to be notified to the other PBX system.
[0025]
The transmitting step at the time of calling determines whether the dialed extension number is for the telephone of the local PBX system or the telephone of the other PBX system when calling the telephone of the local PBX system; When it is determined that the extension number is that of the telephone of the other PBX system, a step of obtaining an IP address corresponding to the extension number and a step of sending a call setting connection request message to the IP address are provided. May be.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a private branch exchange system that performs intersystem connection by IP and a system information transmission method thereof according to the present invention will be described below with reference to FIGS.
[0027]
FIG. 1 shows a system configuration example of the present embodiment. 1, the present embodiment is applied to inter-system connection of PBX systems 1... 1 installed at a plurality of bases such as a head office, a branch office, a sales office, and a factory of a large company. In FIG. 1, a PBX system 1 provides extension calls and other services between a plurality of telephones (extension telephones) 11... 11 connected to the own PBX system 1, and each telephone 11. In addition to the known PBX functions such as exchange connection for external line calls), it is connected to Ethernet (registered trademark) 2 that constitutes a LAN based on the communication protocol of the physical layer and data link layer of the OSI reference model, and this Ethernet (registered trademark) 2, or a router 3 connected thereto, via an IP-VPN (Virtual Private Network) 4 as an IP network (for example, an in-house IP network) 4 and other routers 3. It is equipped with a function that allows extension calls to be made with other PBX systems 1, 1.
[0028]
In order to realize the above functions, the PBX system 1 includes, for example, a CPU 12 that operates by program control as each unit connected on the bus, a control program (see below) such as a communication protocol executed by the CPU 12, control data, and the like. A storage device 13 such as a ROM or a RAM, a telephone I / F (interface) 14 connected to each telephone 11... 11, and an Ethernet controller (LAN controller) 15 responsible for communication control of Ethernet (registered trademark) 2. And built-in. With this configuration, when various types of information are transmitted from the PBX system 1, data is read from the storage device 110 under the control of the CPU 12 and transmitted to the Ethernet (registered trademark) 2 by the ether controller 120.
[0029]
The control program 21 executed by the CPU 12 includes a station interface, a trunk interface, and an inter-system interface as a call control unit (call control program) 22 as shown in FIG. Among these, in addition to the conventionally known ISDN interface, the inter-system interface responsible for inter-system connection by IP, in this embodiment, the IP corresponding to the network layer of the OSI reference model, and the upper layer above the transport layer on this IP H. corresponding to the layer. The H.323 communication protocol is implemented.
[0030]
Of these, H.C. The H.323 communication protocol is standardized by the ITU-T recommendation, and is composed of a plurality of protocols that individually define call control between terminals, audio / video encoding methods, data transmission / reception methods, and the like. .
[0031]
For example, H.M. The call control protocol defined in H.323 includes H.323 corresponding to the session layer and the presentation layer of the OSI reference model that operates under the TCP connection of the transport layer. 225.0 (ITU-T recommendation), H.264. 245 (ITU-T recommendation) protocol is included. For example, H.M. In 225.0, a call control procedure (for example, extension number dialing, acquisition of an IP address from an extension number, connection request message for starting setting of a call addressed to the IP address) (“Setup”) ) A connection permission message (“Connect”) received from the other party by transmission or its response) In H.245, a procedure for negotiation (negotiation) such as which terminal takes the audio / video encoding method and control right is defined. In any protocol, TCP is used as a transport layer protocol.
[0032]
TCP is a connection-oriented communication protocol that waits for receipt confirmation after sending a packet, and sends the next packet when the confirmation arrives. The method of error detection when an error occurs, the method of correcting the error, the method of checking for missing packets, the procedure of assembling data based on the received packet, etc. are defined.
[0033]
H. The speech coding system defined in H.323 is a PCM (Pulse Code Modulation) system G.264. 711 (ITU-T recommendation) and CELP (Code-Excited Linear Prediction) G. Protocols such as 729 (ITU-T recommendation) are defined. In either protocol, UDP (User Datagram Protocol) is used as a transport layer protocol instead of TCP, and RTP (Real-Time Transport Protocol) is used as a session layer protocol.
[0034]
UDP is a connectionless communication protocol that transmits data unilaterally and, unlike TCP, does not perform error control or error control retransmission processing, and has a higher communication speed. RTP is a protocol for sending real-time data such as voice and video, and is a function that attaches time stamps to packets to control the order of data, and plays back in synchronization with the order of transmission or discards with a large delay Have
[0035]
Next, the overall operation of this embodiment will be described in detail with reference to the control flowcharts of FIGS. 2 and 3. Processing of each step of the control flowchart shown in FIGS. 2 and 3 is performed by the CPU 12 executing the call control unit 22 of the control program 21 stored in the storage device 13.
[0036]
First, as shown in FIG. 3, when the extension number of the telephone 11 of the own PBX system 1 is dialed by the telephone 11 of the own PBX system 1 on the transmission side (step S1), the CPU 12 of the own PBX system 1 The dialed extension number is input via the telephone I / F 14, and it is determined whether the extension number is for the telephone 11 of the other PBX system 1 or the telephone 11 of the own PBX system 1 (step S2). . This determination is made, for example, based on a correspondence table of identification numbers and extension numbers of the PBX system stored in the storage device 13 in an updatable manner.
[0037]
If it is determined as a result of the process of step S2 that the dialed extension number is that of the telephone 11 of the other PBX system 1, the CPU 12 of the own PBX system 1 Is acquired (step S3). This IP address acquisition is performed, for example, based on a correspondence table between extension numbers and IP addresses stored in the storage device 13 in an updatable manner. Then H. In accordance with a call control procedure according to the H.323 protocol, an IP packet of “Setup”, which is a call setting connection request message, is sent to the Ethernet (registered trademark) 2 via the Ethernet controller 15 (step S4).
[0038]
As a result, the IP packet of the “Setup” message is sent to the other router 3 via the IP-VPN 4 by IP routing by the router 3 and reaches the other PBX system 1. If there is no problem in connection, the other party's telephone 11 sends out a “Connect” IP packet of a connection permission message, and an incoming call is made with a ringing tone. As a result, when call setting is performed between the telephones 11 and 11 of the own and other PBX systems 1 and 1, the H.264 and H.PBX systems 1 and 1 thereafter. In accordance with the H.323 protocol, the analog voice signal from the telephone set 11 is encoded into a digital signal by the voice encoding method determined by the above negotiation, and in accordance with the UDP and RTP protocols, the RTP header, UDP header, An IP packet to which an IP header is attached is transmitted on the Ethernet (registered trademark) 2 via the Ethernet controller 15. In this manner, voice data is transmitted and received, and an extension call is established by IP connection between the telephone 11 of the own PBX system 1 and the telephone 11 of the other PBX system 1.
[0039]
On the other hand, if it is determined as a result of the processing in step S2 that the dialed extension number is that of the telephone 11 of the own PBX system 1, an extension incoming call or other service in the own system is executed (step S5). . As an example of the service in the own system provided here, for example, known PBX such as incoming / outgoing / outgoing calls, camp-on, paging, conference call, park hold, terminal status display, busy call, call interruption, call transfer, etc. A service by function can be exemplified. Thus, an extension call or the like is performed between the telephones 11 and 11 in the own PBX system 1.
[0040]
Thereafter, the CPU 12 executes a control program 21 stored in the storage device 13 to establish another connection by TCP (step S6), and the terminal (telephone 11) state that needs to be notified to the other party, System information is notified (step S7). Information not directly related to the call is also notified to the other party's PBX system 1 through this TCP connection.
[0041]
As the notification of the state change of the terminal (telephone) 11) transmitted through the TCP connection established here, for example, “idle”, “busy”, “transfer setting / DND setting”, etc. can be exemplified. Including this, other park hold information notifications, etc. Information that is difficult to transmit in H.323 is also transmitted through a TCP connection established separately here.
[0042]
On the other hand, as shown in FIG. 4, on the incoming side, the CPU 12 executes the control program 21 stored in the storage device 13, thereby When an incoming call is detected according to the H.323 protocol (step S11), an extension incoming call and other services in the own PBX system 1 are executed (step S12). As a result, an extension call based on IP connection or an extension call between the telephones 11 in the own PBX system 1 is performed between the telephone 11 of the own PBX system 1 and the telephone 11 of the other PBX system 1.
[0043]
Thereafter, the CPU 12 establishes a TCP connection separately, and sends system information on the receiving side through this TCP connection (step S13). This system information is the same as described above, that is, information that is not directly related to the call of the own PBX system 1, and the terminal status that needs to be notified to the other party ("idle", "busy", "transfer setting / DND setting", etc.) , Other park hold information notifications, etc. 323 includes information that is difficult to transmit.
[0044]
Therefore, according to this embodiment, H.264 is used as the interface protocol. Using the H.323 protocol, functions similar to those of a single system can be realized between connected systems. In addition, various information in the system is stored in H.264 using a TCP connection generated separately. 323 can be notified by a separate system, and information in the system such as terminal status information and notification of various settings can be exchanged even when a call is not generated. In addition, since the TCP connection has the properties of both a server and a client, it is possible to request connection establishment from both directions without worrying about the server / client. This makes it possible to make a connection request to the partner port if there is a message transmission request from a state where the connection has not been established, and to accept if there is a connection request to its own port. In this way, connection between PBX systems and transmission of system information by IP becomes possible.
[0045]
It should be noted that the present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will recognize various modes based on the description in the scope of the claims without departing from the spirit of the invention. Can be modified and changed. These changes and modifications also belong to the scope of rights of the present invention.
[0046]
【The invention's effect】
As described above, according to the present invention, in the inter-system connection of extension calls in a plurality of PBX systems, the IP connection can be performed relatively inexpensively without providing an IP gateway separately, and abnormal operation is caused by compatibility with the device. It is possible to provide a private branch exchange system that performs inter-system connection by IP and a system information transmission method thereof that can avoid a situation that occurs.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing the overall configuration of a private branch exchange system that performs intersystem connection by IP according to the present invention.
FIG. 2 is a diagram showing a configuration of a control program.
FIG. 3 is a flowchart showing a control procedure during transmission.
FIG. 4 is a flowchart showing a control procedure when an incoming call is received.
[Explanation of symbols]
1 PBX (private branch exchange) system 2 Ethernet (registered trademark) (LAN)
3 Router 4 IP-VPN (IP network)
11 Telephone (extension telephone)
12 CPU
13 Storage Device 14 Telephone I / F (Interface)
15 Ether Controller (LAN Controller)
21 Control program 22 Call control unit

Claims (6)

A plurality of PBX (Private Branch eXchange) systems that are communicably connected to each other via a LAN (Local Area Network) according to a communication protocol of IP (Internet Protocol), and a plurality of telephones mounted on each PBX system. Prepared,
The plurality of PBX systems are:
A LAN controller connected to the LAN;
H. H.323, which executes call control for the plurality of telephones via the LAN between its own and other PBX systems according to the H.323 call control protocol. 323 call control means;
TCP connection establishment means for establishing a TCP connection via the LAN between the own and other PBX systems in accordance with a TCP (Transmission Control Protocol) communication protocol;
When calling the telephone of the PBX system, the H. When making a call by sending predetermined system information from the LAN controller to the other PBX system via the LAN after the call is made by the call control by the H.323 call control means and the TCP connection established by the TCP connection establishment means. A transmission means;
When an incoming call is received from the telephone of the own PBX system, When an incoming call is received by call control by the H.323 call control means, and then predetermined system information is transmitted from the LAN controller to the other PBX system via the LAN by the TCP connection established by the TCP connection establishment means. A private branch exchange system for performing inter-system connection by IP, comprising a transmission means. 2. The inter-IP system according to claim 1, wherein the predetermined system information includes system information not directly related to a call of the own PBX system and information on a telephone state that needs to be notified to the other PBX system. Private branch exchange system for connection. The calling time transmitting means determines whether the dialed extension number is that of the own PBX system telephone or the other PBX system telephone at the time of calling of the own PBX system telephone; A means for obtaining an IP address corresponding to the extension number and a means for sending a call setting connection request message to the IP address when it is determined that the extension number is that of the telephone of the other PBX system; The private branch exchange system for performing intersystem connection by IP according to claim 1 or 2. A plurality of PBX (Private Branch eXchange) systems that are communicably connected to each other via a LAN (Local Area Network) according to a communication protocol of IP (Internet Protocol), and a plurality of telephones mounted on each PBX system. The system information transmission method used,
The plurality of PBXs are
H. H. 323 executes call control for the telephone via the LAN between its own and other PBX systems according to the H.323 call control protocol. 323 call control step;
A TCP connection establishment step for establishing a TCP connection between the own and other PBX systems via the LAN according to a TCP (Transmission Control Protocol) communication protocol;
When calling a telephone in the own PBX system, A call transmission step of transmitting predetermined system information to the other PBX system via the LAN after a call is made by call control in the H.323 call control step, and a TCP connection established by the TCP connection establishment step;
When the telephone in the PBX system is called, the H. An incoming call transmission step of transmitting predetermined system information to the other PBX system via the LAN after the incoming call is made by the call control in the H.323 call control step and the TCP connection established in the TCP connection establishment step. The system information transmission method characterized by having provided. 5. The system information transmission method according to claim 4, wherein the predetermined system information includes system information not directly related to a call of the own PBX system and information on a telephone state that needs to be notified to the other PBX system. . The transmitting step at the time of calling determines whether the dialed extension number is for the telephone of the own PBX system or the telephone of the other PBX system when calling the telephone of the own PBX system; When it is determined that the extension number is that of the telephone of the other PBX system, the method includes the steps of obtaining an IP address corresponding to the extension number and sending a call setting connection request message to the IP address. 6. The system information transmission method according to claim 4, wherein the system information is transmitted.

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