JP2002319961A - Private branch exchange and communication connecting method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a private branch exchange capable of performing speech communication by a connection procedure that conforms to a multimedia transmission system provision under an IP network environment where different address spaces are mixed, and a communication connecting method thereof. SOLUTION: An IP-PBX 10 extracts a PA allocated as compressed information from a prescribed area in which information is written on a multimedia standard in data areas of packets 120 respectively supplied from a plurality of terminal devices of a network of a private address(PA) space in an address extraction functioning part 142, supplies a PA 124 obtained by performing decompressing processing of the PA to an address conversion functioning part 144, retrieves a PA 126 coinciding with the PA 124 extracted in the address conversion functioning part 144 from a NAT conversion table 146, replaces a global address(GA) of the NAT conversion table 146 corresponding to the PA 126 with the extracted PA in accordance with retrieval results and outputs an IP packet 134 written as compressed information in a prescribed area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a private branch exchange and a communication connection method therefor, and is suitable for use, for example, in a private branch exchange compatible with the Internet for making a call connection in a multimedia standard environment.

[0002]

2. Description of the Related Art At present, with the spread of the Internet, Vo
-IP (Voice-Internet Protocol) is starting to attract attention. Vo-IP is a technology that puts voice information on IP packets. It allows voice and data to coexist in a LAN (Local Area Network) environment, and is attracting attention in terms of reducing call costs and equipment investment. . Demand for telephone exchanges (hereinafter referred to as IP-PBXs) that support IP based on this Vo-IP is gradually increasing. IP-PBXs are to be operated in various network environments according to demand.

The conventional IP-PBX call connection method is based on ITU-
T (International Telecommunication Union-Telecommu
It adopts a connection procedure that conforms to Recommendation H.323 (packets based on multimedia transmission systems: February 1998) for non-telephone signal transmission lines in the communication standardization sector. This connection procedure is roughly divided into three stages.

First, Recommendation Q.931 (ISDN (Integrated Serv
ices Digital Network) User / Network Interface /
Set up by the procedure of Layer 3 Basic Call Control Specification (SE
Negotiate connection information (IP address, port and number) using TUP), call (ALERT), and connection (CONN). The connection information is used in the procedure of the following Recommendation H.245. Recommendation H.245 specifies a control protocol for multimedia transmission.

In the procedure of Recommendation H.245, TCS (Terminal Cap
ability Set) and TCSA (Terminal Capability Set A)
negotiation of the terminal information of Recommendation H.323 by using Cknowledge), and MSD (Master Slave Determination)
And MSDA (Master Slave Determination Acknowledg)
e) is used to make a master-slave decision and OLC (Op
en Logical Channel) and OLCA (Open Logical Chann)
Negotiation of connection information used in a call is performed using el Acknowledge). The call here is RTCP
RTP with (Real-Time Transport Protocol)
(Real-time Transport Protocol) transmission of audio and video, etc., without securing resources or guaranteeing quality, and is transmission that does not depend on the protocol of the transport layer or the network layer. In the call state, RTP and RTCP connections are established between the terminals of Recommendation H.323.

[0006] In addition, the conventional IP-PBX uses the H.323 recommended high-speed connection (Fast Connect) in order to shorten the call connection time.
In some cases, the connection procedure conforms to the standard. The connection procedure in this case is divided into two stages. In the first stage, negotiation is first performed for connection information. For the connection information, the connection information of RP and RTCP is obtained together with the connection information used in Recommendation H.245 from the procedure of Recommendation Q.931 as in the connection procedure described above. In the second stage, a communication state is established by establishing a connection of RTP and RTCP between terminals of recommendation H.323.

As can be seen from the connection procedure described above, terminal devices obtain connection information of RTP and RTCP while negotiating with each other using a message of recommendation H.323, and based on this information, A call is established by establishing a connection between the terminal devices of Recommendation H.323.

[0008]

By the way, an IP-PBX for realizing the above-mentioned connection procedure is provided in each network that handles a private address space and a global address space, and based on the difference in the address space between these networks.
Use NAT (N
etwork Address Translation) When configured to communicate via a router, it is actually a recommendation H.
A connection cannot be established between 323 terminal devices, and a call cannot be made. This occurs in any connection procedure based on the above-described two types of recommendation H.323 and H.323FastConnect.

The present invention solves the above-mentioned drawbacks of the prior art, and enables a private branch exchange capable of making a call by a connection procedure conforming to the rules of the multimedia transmission system even in an IP network environment where different address spaces are mixed. An object of the present invention is to provide a communication connection method.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a private branch exchange which is provided in a private network and is communicatively connected to a network under an Internet Protocol (IP) environment. The exchange sets the address handled on the private network as the first address and the address handled on the network under the IP environment as the second address, and stores the first address and the second address in advance in a fixed manner in association with each other. And a first address assigned as compressed information from a predetermined area in which information of a multimedia standard is written in a data area of a packet supplied from each of a plurality of terminal devices in a private network. The address extraction function block to be extracted and the extracted first address A first address that matches the address is retrieved from the storage unit, and the extracted first address is replaced with the second address stored in the storage unit in accordance with the search result, and the predetermined address is converted into compressed information. And an address conversion function block for writing data in the area of (1).

The private branch exchange according to the present invention uses an address extraction function block to compress information from a predetermined area in which multimedia standard information is written in a data area of a packet supplied from each of a plurality of terminal devices in a private network. The first address assigned as the first address is extracted, the first address matching the first address extracted by the address conversion function block is searched from the storage means, and the storage corresponding to the first address is stored according to the search result. The first address extracted by the second address of the means is replaced, the information is compressed and written in a predetermined area, and a function equivalent to the so-called static NAT function corresponding to the multimedia standard is performed. A response from the private branch exchange on the network side of the second address space to the private network side And working to establish a negotiation in each step between predetermined extracts second address written in the area different receiving a response signal written in the address location of the destination network as the address of the destination to be used.

In order to solve the above-mentioned problems, the present invention relates to a communication connection method of a private branch exchange which is provided in a private network and is connected to a network under an Internet Protocol (IP) environment. In the method, an address handled in a private network is set as a first address, an address handled in a network under an IP environment is set as a second address, and multiple addresses in a data area of a packet respectively supplied from a plurality of terminal devices in the private network are set. A first method for extracting compressed information from a predetermined area in which information of a media standard is written
A second step of subjecting the extracted information to decompression processing, and using the decompressed information as a first address,
A second step of searching for a match between the first address and the first address stored in the exchange in advance, and a second step of storing corresponding to the first address stored in the exchange in response to the search result A third step of replacing the expanded information with the address, a fourth step of performing a compression process on the replaced second address, and a fifth step of writing the compressed second address into a predetermined area And characterized in that:

According to the communication connection method of the private branch exchange of the present invention, compressed information from a predetermined area in which information of a multimedia standard is written in a data area of a packet respectively supplied from a plurality of terminal devices in a private network is written. The information is extracted and subjected to a decompression process. The obtained information is used as a first address. The first information is compared with a first address stored in the exchange in advance to search for a match between the two.
The decompressed information is replaced with the second address corresponding to the first address stored in the exchange according to the search result, the replaced second address is subjected to compression processing, and the compressed second processing is performed.
By writing the address in a predetermined area, a packet is sent to the IP network side with a so-called static NAT function corresponding to the multimedia standard, and negotiations in different procedures between different networks are established. ing.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a private branch exchange according to the present invention will be described in detail with reference to the accompanying drawings.

In this embodiment, a private branch exchange (hereinafter, referred to as IP-PBX) 10 corresponding to IP to which the private branch exchange of the present invention is applied will be described. Illustrations and descriptions of parts not directly related to the present invention are omitted. Here, the reference numerals of the signals are represented by the reference numbers of the connecting lines in which they appear.

As shown in FIG. 1, the IP-PBX 10 includes a LAN interface unit 12, a system control unit 14, and a NAT router 16.

The LAN interface unit 12 is an input / output interface corresponding to one form of signals supplied from a plurality of terminal devices (not shown), and is a line circuit. In the present embodiment, a digital signal 120 obtained by subjecting each signal supplied from the private network to level adjustment or the like is transmitted to the system control unit 14. The signal line 120 is a line through which control and data are passed. LAN interface section 12
Is connected to the NAT router 16 via a hub or a LAN switch (not shown), and performs bidirectional communication.

The system control unit 14 uses a switching program such as a call processing function, a system operation function, a failure processing function, and an execution management function to execute the LAN interface unit 1 for each type.
2. A control system for processing the NAT router 16 respectively. In this embodiment, a call control unit 140 for controlling call processing is shown in FIG. 1 to clarify the features of the present invention.
Is shown in

The call control unit 140 includes a private address (hereinafter, referred to as PA) extraction function unit 142,
An address translation function section 144 and a NAT translation table 146 are provided. The PA extraction function unit 142 transmits the multimedia standard data to a terminal device in the IP network to establish a communication connection by using a TCP (Transmissio
n Control Protocol) data area
It has the function of reading PA. The call control unit 140
Are temporarily stored in a memory so as to prevent loss of the supplied packet data 120.

The PA extraction function unit 142 includes an area extraction function unit 142a and a decompression function unit 142b as shown in FIG. 2 to realize this function. Area extraction function unit 142a
Specifies the above-mentioned data area in the supplied packet data 120 from the message, and extracts the PA data 122 in consideration of the data structure of the message described later. The area extraction function unit 142a stores the extracted PA data 12
2 is sent to the extension function unit 142b.

The decompression function unit 142b performs decompression processing on the PA data 122. This is because the PA data 122 is compressed data. The compression format is ANS1 PER (Abstract Syn
tax Notation 1 Packed Encoding Rules) encoding (IT
UT Recommendations X.691, X.680, X681). Therefore, the decompression process is a reverse process of the compression format.
As a result of this processing, the PA 124 of the terminal device in the supplied packet data 120 is known. The PA extraction function unit 142 sends the extracted PA 124 to the address conversion function unit 144.

As shown in FIG. 2, the address change function unit 144 includes a private address search function unit 144a, a global address selection function unit 144b, a compression function unit 144c, and an area write function unit 144d. Address translation function unit 14
Reference numeral 4 is connected to a NAT conversion table 146 via a signal line 126 in order to exert an address conversion function.

The NAT conversion table 146 has an IP-PBX
Private address (PA) and IP handled by 10 terminal devices
Global address used in the network (Global Add
ress: hereinafter referred to as GA). The NAT conversion table 146 can be easily rewritten if it is desired to change it, for example, during maintenance or the like.

In the address conversion function section 144, the PA search function section 144a performs the PA 1 conversion from the PA 124 and the NAT conversion table 146.
26 and has a function of performing a search depending on whether or not there is a match. In the comparison, if all the supplied bit data of the data are the same, it is considered that they match, and if even one is different, it is determined that they do not match. PA search function section 144a outputs match signal 128 to global address selection function section 144b when the search results match. The GA selection function unit 144b selects the GA corresponding to the matched PA and reads out the GA from the NAT conversion table 146 to the GA selection function unit 144b via the signal line 126. The GA selection function unit 144b supplies the GA 130 to the compression function unit 144c.

The compression function unit 144c converts the supplied data, that is, the GA 130, into the above-described ANS1 PER encoding (ITU-T recommendation).
X.691, X.680, X681). The compression function unit 144c supplies the compressed GA 132 to the area writing function unit 144d. The area writing function unit 144d has a function of reading out the packet data 120 temporarily stored by the call control unit 14 and writing the GA 132 in the same area as that extracted before the packet data 120. The area writing function unit 144d returns the packet data 134 to which the GA 132 has been written to the LAN interface unit 12 via the signal line 120. The LAN interface unit 12 NATs the data 12a subjected to the address conversion processing for each packet data.
The data is supplied to the router 16 to exchange data.

Returning to FIG. 1, the NAT router 16 includes a CPU (Central Processing Unit), a memory, a flash memory, an interface card, and other hardware for assisting operation, although not shown. CPU
Executes a calculation process, and the memory stores the result of the calculation process and temporarily stores received data. The flash memory stores information to be stored even when the power is turned off. This information includes, for example, a dedicated OS (Op
erating system) and a NAT table stored as a comparison table between private addresses and global addresses. The NAT router 16 is connected to an IP network via a signal line 16a. In this way, the components of the IP-PBX 10 are connected to establish exchange of multimedia standard information in different address spaces.

Next, before describing the operation of the IP-PBX 10,
The structure of the packet 30 will be briefly described. IP packet 30
It comprises an IP header 32 and an IP payload. It is composed of a data part 34 of the packet. IP header 32
In the area where information is recognized between the network layers, the IP header 32 stores the source IP address in the area 32a and the destination IP address in the area 32b.

The IP payload 34 is a data area of the IP packet 30, and the head area of the data area is TCP (Transmissio).
n Control Protocol) header 36. The TCP header 36 is a transport header.
Although not shown, for example, a source port number and a destination port number are stored. Of the IP payload 34,
The data area excluding the TCP header 36 is the TCP payload 38.

The IP-PBX 10 of this embodiment is controlled to perform communication with different address spaces according to the ITU recommendation H.323 (February 1998) defined for packets based on the multimedia transmission system. I do. In performing this multimedia communication, first, connection information is negotiated in the order of Recommendation Q.931 and Recommendation H.245. Since this negotiation is performed in each of the above-described procedures, the TCP payload 38 has, for example, an area in a format schematically shown.
Information indicating the address space of the transmission source is written to 38a for each message of each procedure. The source address space information is a private address (PA).

The message of each procedure is defined in Recommendation Q.93.
1 and a message collectively indicating the commands used in Recommendation H.245 are referred to as Recommendation H.323 messages. That is, Recommendation H.3
The 23 messages are, for example, SETUP, ALERT, CONN, CALL_PROC (CALL_PROCedur
e), TCS which is the message of FACILITY and Recommendation H.245
(Terminal Capability Set), TCSA (Terminal Capabil
ity Set Acknowledge), MSD (Master Slave Determinati)
on), MSDA (Master Slave Determination Acknowledg
e), OLC (Open Logical Channel), OLCA (Open Logical Channel)
Channel Acknowledge). These recommendations H.323
The data structure of a message containing a PA differs depending on the procedure and its type. For example, the messages OLC, OLCA specified in Recommendation H.245 have three data structures 380, 382, 384 including PA. The message specified in Recommendation Q.931 is also represented by one to three data structures depending on the message type. For example, SETUP
Has three structures, CONN has two structures, and CALL_PROC,
ALERT and FACILITY have one structure. Each of these structures includes PA.

However, an IP having such a structure
In the packet 30, when IP address conversion is performed using the NAT function, IP transparency becomes incomplete. This is because the router only recognizes up to the network layer, so the PA in the H.323 message written in the TCP payload 38 at the time of transmission is transmitted as it is, and the GA (Global Addres
This is because the address is not converted to s). That is, despite the use of the NAT router 16, the IP address of the IP header to which the response signal supplied from the destination terminal device is returned is PA, so that the IP-PBX 10 The address conversion for the IP packet cannot be performed normally, and as a result, it cannot be correctly returned to the terminal device in the PA space. Thereby, the terminal device of the recommendation H.323 under the IP-PBX of the PA space and the terminal of the recommendation H.323 under the IP-PBX of the GA space in the connection procedure based on the recommendation H.323 and the recommendation H.323 FastConnect The device cannot establish a connection. Therefore, a call cannot be made between the terminal devices of Recommendation H.323 operating in different address spaces.

The IP-PBX 10 to which the present invention is applied has a call control unit 1
At 40, the PA written in the message of the recommendation H.323 in the TCP payload 38 is converted to GA. Next, the procedure of address conversion of the IP-PBX 10 will be briefly described. However, the operation as the IP-PBX is basically the same as that of the IP-PBX standard except for the address translation processing for the message storage area 38a (see FIG. 3). Is the same. In order to avoid complicated description, the description is limited to address conversion processing.

This is a process when multimedia information from a terminal device of the recommendation H.323 in the PA space side is received by the IP-PBX 10 in a connection procedure conforming to the recommendation H.323 and the recommendation H.323 FastConnect. . First, the information is temporarily stored in a memory (not shown) via the LAN interface unit 12, and the multimedia information 120 is supplied to the call control unit 140. PA in the multimedia information 120 supplied by the PA extraction function unit 142
Is extracted (step S10). PA extraction, PA extraction function section
At 142, it is taken out from the area of the corresponding data structure in consideration of which procedure and the type of the supplied recommendation H.323 message. Although not shown in FIG. 4, since the PA 122 is information that has been subjected to compression processing, the PA extraction function unit 142 performs decompression processing on the extracted information. The expanded PA 124 is supplied to the address conversion function unit 144.

Next, the presence or absence of an address is determined by the PA search function section 144a (step S12). When there is no address (NO),
It is determined that the information is not multimedia information, and the process is terminated. At this time, the IP-PBX 10 may return a message to the user to the terminal device in the PA space to the effect that communication was not possible by voice or the like. When the address is found (YES), the NAT conversion table 146 is stored in the PA search function section 144a.
From the stored PA 126.

Next, PA 126 read by PA search function section 144a
Is compared with the extracted PA 124 (step S14). The comparison is made based on whether the bit data of the PAs 124 and 126 match. The PA search function unit 144a supplies the match signal 128 to the GA selection function unit 144b according to the comparison result. The determination of a match according to the comparison result is step S16. When the comparison result indicates a match (YES), the process proceeds to step S18. When the compared PA 126 does not match (N
O), and proceed to step S20.

Next, a GA for address conversion is selected (step S18). For this selection, the GA corresponding to the matched PA in the NAT conversion table 146 is read by the GA selection function unit 144b. GA
The selection function unit 144b supplies the GA 130 to the compression function unit 144c. Although not shown in FIG. 4, the GA 130 is subjected to a compression process. The compression function unit 144c supplies the compressed GA 132 to the area writing function unit 144d.

Next, the GA 132 is written into the packet 120 read from the memory in which the GA 132 is temporarily stored (step S22). The area writing function unit 144d sets G in the area where the PA of the packet 120 is extracted.
Write A 132 to replace PA and GA. The packet 134 replaced with the GA is output from the area writing function unit 144d to the LAN interface unit 12. After this output, the address conversion process ends.

On the other hand, when the comparison result does not match in step S16 (NO), the PA search function unit 144a reads a new PA 126 that has accessed the NAT conversion table 146. Then, in step S20, when there is no new PA 126 from the NAT conversion table 146 (YES), it can be understood that the search result does not match.
At this time, the IP-PBX 10 may return a message to the user. When a new PA 126 is present (NO), the new PA is read and the comparison of the PA is repeated.

Further, the terminal device 10 in different address spaces
A sequence for establishing a connection with 0-200 will be briefly described (see FIG. 5). Where NAT router 16
Is intentionally separated from the IP-PBX 10 to distinguish it from the newly provided static NAT function of the IP-PBX 10. NAT router
It is assumed that 16 has a virtual address space boundary 40. The boundary 40 is divided into a PA space 42 and a GA space 44.

The terminal device 100 sets the SETU indicating the Q.931 procedure.
An IP packet 46 including the message P is sent to the IP-PBX 10. The IP-PBX 10 translates the PA included in the message of the recommendation H.323 of the IP packet 46 to the GA. Call control unit 14
The IP packet 48 whose address has been translated at 0 is
It is supplied to the NAT router 16 via the N interface unit 12.

The NAT router 16 converts the address of the PA in the IP header 32 to the GA, and sends the IP to the IP-PBX 50 under the GA space.
The packet 52 is being supplied. The IP-PBX 50 supplies, as an IP packet 54, to the terminal device 200 conforming to the recommendation H.323 of the other party while performing processing according to each layer.

The terminal device 200 transmits the IP packet 56 including the message (ALERT) of the recommendation H.323 in response to the SETUP of the recommendation Q.931 procedure included in the IP packet 54. At this time, the terminal device 200 transmits the message (data area) of the IP packet 54.
Is written to the destination address of the IP header. The IP-PBX 50 sends the IP packet 56 supplied from the terminal device 200 to the NAT router 16 as an IP packet 58.

It goes without saying that the address information in the recommendation H.323 message transmitted from the terminal device 200 on the GA space 44 side is not changed.

The NAT router 16 converts the GA written as the destination address of the IP header into a PA,
The IP packet 60 converted to is transmitted to the IP-PBX 10. IP-
The PBX 10 receives the IP packet 60, and
An IP packet 62 is transmitted to the terminal device 100 corresponding to A. As described above, the connection information is sequentially supplied to the terminal devices 100 and 200 in both address spaces by a series of processes, so that negotiation between the two terminal devices is established.

Therefore, the procedure of Recommendation Q.931, Recommendation H.245
Are sequentially performed by the terminal devices 100 and 200, communication in different address spaces is secured, and thereafter, multimedia communication is performed by exchanging RTP and RTCP. Recommendation H.323
H.323 Fast Connect
In the call connection procedure according to the above, negotiation can be established by similarly performing address conversion.

With the above configuration, the address extraction function unit 142 in the call control unit 140 uses the address extracting function unit 142 in the PA space network to multiplex packets supplied from a plurality of terminal devices (not shown) in the data area. The PA assigned as compressed information is extracted from the predetermined area 38a in which the information of the media standard is written, and the PA 124 obtained by the decompression processing is supplied to the address conversion function unit 144. PA 126 matching the extracted PA 124 is N
Search from AT conversion table 146 and PA 12 according to the search result
6 in the NAT conversion table 146 corresponding to 6 and outputs the IP packet 134 written in the predetermined area 38a as compressed information by replacing the extracted PA, so that the so-called static It has a function equivalent to a typical NAT function.

Therefore, the terminal device on the IP network side
200 extracts the destination address of the response packet from the supplied IP packet 50 and converts the response packet 56 into an IP-PBX 50
Send to The response packet is an IP packet indicating a response from the network side in the GA space to the network side in the PA space. In the extraction of the destination address, the GA that has been written is extracted from the above-described predetermined area of the data. This GA
Even if a response packet written in the destination address position of the IP header is supplied from the IP-PBX 50 to the NAT router 16, the destination address can be converted into a PA corresponding to the GA, so that the A response signal of an IP packet can be supplied to a terminal device in the PA space, and thus a different PA
By establishing the negotiation of each procedure even between the -GA networks, multimedia communication conforming to the recommendation H.323 is enabled between the PA and the GA, which can greatly contribute to reduction of communication cost.

[0048]

As described above, according to the private branch exchange of the present invention, the address extraction function block writes the multimedia standard information in the data area of the packet supplied from each of the plurality of terminal devices in the private network. The first address assigned as the compressed information is extracted from the area (a), the first address that matches the first address extracted by the address conversion function block is searched from the storage unit, and the first address is searched according to the search result. The first address extracted is replaced with the second address of the storage means corresponding to the address No. 1 and the information is compressed and written in a predetermined area to obtain a so-called static address corresponding to the multimedia standard. Provide a function equivalent to the NAT function, and respond from the private branch exchange on the IP network side to the private network side By extracting a second address written in a predetermined area as a destination address to be used and receiving a response signal written in the destination address position, establishing a negotiation in each procedure between different networks, Even in a network environment in which space is mixed, multimedia communication is enabled and multimedia communication is enabled, which can greatly contribute to reduction of communication cost.

Further, according to the communication connection method of the private branch exchange of the present invention, compression is performed from a predetermined area in which information of a multimedia standard is written in a data area of a packet supplied from each of a plurality of terminal devices in a private network. The extracted information is extracted, the information is subjected to a decompression process, the obtained information is used as a first address, and compared with a first address stored in the exchange in advance to search for a match between the two. In response, the exchange replaces the expanded information with a second address corresponding to the first address, compresses the replaced second address, and writes the compressed second address in a predetermined area. With a so-called static NAT function corresponding to the multimedia standard, a packet is sent to the network side of the second address space, By establishing negotiation in each step between the networks, the first and second address contributes significantly to enable the communication costs reduced were multimedia communication even under a network environment coexist.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an IP-PBX to which a private branch exchange according to the present invention is applied.

FIG. 2 is a functional block diagram showing a schematic configuration of a PA extraction function unit and an address conversion function unit in the call control unit of FIG. 1;

FIG. 3 is a diagram schematically illustrating a data structure of an IP packet including multimedia information supplied to the IP-PBX of FIG. 1;

FIG. 4 is a flowchart illustrating a procedure for performing static NAT conversion on multimedia information in the IP-PBX of FIG. 1;

FIG. 5 is a sequence chart in a case where negotiation is performed in different address spaces using the IP-PBX of FIG. 1;

[Explanation of symbols]

 10 IP-PBX (Private Branch Exchange supporting IP) 12 LAN interface unit 14 System control unit 16 NAT router 140 Call control unit 142 PA extraction function unit 144 Address conversion function unit 146 NAT conversion table

Claims (4)

[Claims] 1. A private branch exchange, which is provided on a private network and is communicatively connected to a network under an Internet Protocol (IP) environment, wherein the private exchange exchanges an address handled by the private network with a first address.
Storage means in which the first address and the second address are fixedly associated with each other in advance and the address handled in the network under the IP environment is a second address; An address extraction function block for extracting a first address allocated as compressed information from a predetermined area in which information of a multimedia standard is written in a data area of a packet supplied from each of a plurality of terminal devices; A first address that matches the first address obtained is searched from the storage unit, and the extracted first address is replaced with a second address stored in the storage unit according to the search result. An address conversion function block for writing the given information in the predetermined area. Internal exchange. 2. The exchange according to claim 1, wherein the address extraction function block extracts an information written in the predetermined area in the data area, and an information extraction function block extracts the information written in the predetermined area in the data area. A private branch exchange comprising an information decompression function block for performing decompression processing. 3. The exchange according to claim 1, wherein said address translation function block is a first address of said storage means corresponding to a first address obtained by performing a decompression process in said address extraction function block. An information retrieval function block for retrieving an address and selecting a second address of the storage means corresponding to the obtained first address; and information compression for performing a compression process on the second address obtained by the retrieval. A private branch exchange comprising: a function block; and an information writing function block for writing the compressed information in the predetermined area. 4. A communication connection method for a private branch exchange which is provided on a private network and is communicatively connected to a network under an Internet Protocol (IP) environment, the method comprising: 1
A predetermined area in which information of a multimedia standard is written in a data area of a packet supplied from each of a plurality of terminal devices in the private network, the second address being an address handled in a network under the IP environment. A first step of extracting the compressed information from the first information, a second step of performing an expansion process on the extracted information, and a first address in which the expanded information is used as a first address and stored in advance by the exchange. A second step of searching for a match between the two by comparing with the address, and replacing the decompressed information with a second address stored corresponding to the first address stored in the exchange according to the search result. A third step of performing a compression process on the replaced second address, and writing the compressed second address into the predetermined area; A communication connection method for a private branch exchange.