JP2005072673A - Method, apparatus and system for telephone exchange - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method, apparatus and system for telephone exchange whereby a telephone terminal controlled by an exchange can attain an additional call control function such as a hold transfer service independently of a call control protocol installed in an opposite telephone terminal. <P>SOLUTION: The method is an IP phone exchange method for connecting a plurality of IP phone terminals respectively belonging to at least two networks operating on different protocols from each other, employs at least one relay address, connects each of a plurality of the IP phone terminals to the relay address in compliance with the corresponding protocol in response to a call connection request among a plurality of the IP phone terminals and sets cross-reference among the addresses of a plurality of the IP phone terminals connected via the relay address to a transfer table. Then the method once receives packets of speech signals transmitted from each of a plurality of the IP phone terminals at the relay address and thereafter transmits the packets to transfer destination addresses in cross-reference with the packet sender address on the basis of the transfer table to attain speech among a plurality of the IP phone terminals. The telephone exchange and system disclosed herein perform the exchange method as above. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a telephone exchange method, apparatus, and system for transmitting / receiving a telephone call signal via a packet data network such as an IP telephone based on VoIP (Voice over Internet Protocol) technology.
[0002]
[Prior art]
By using the VoIP technology, a telephone call via the IP network is possible. Telephone communication by such a method is generally called an IP telephone. As for the use of IP telephones, the transition from conventional analog telephones to IP telephones is particularly progressing in extension communication in large-scale organizations such as companies.
[0003]
The extension communication is often used not only by making a telephone call between departments in an organization but also by transferring an external line between departments as appropriate. For this reason, in the conventional analog telephone system, an organization having a large number of extension telephones has installed a private branch exchange (hereinafter referred to as PBX) and used this to realize such a forwarding service and an accompanying hold service. .
[0004]
By the way, the private branch exchange in the IP telephone terminal is called IP-PBX. Such an IP-PBX accommodates a large number of extension telephones as in the case of the conventional PBX, and has a variety of functions such as a function of connecting to an office line of an external public telephone network and a gateway function of connecting to an external IP network such as the Internet. It can be equipped with various functions.
In order for such IP-PBX to provide additional services similar to those of conventional PBX, control of multi-function telephones and gateways under the PBX is realized by exchanging original control information (hereinafter referred to as an original protocol). There are a lot of products. In this case, the IP-PBX terminates call control information with an external IP telephone terminal in accordance with a standard protocol (for example, H.323), and substitutes it with the original protocol as described above, thereby substituting the IP under it. Call control is possible with a telephone terminal.
[0005]
[Problems to be solved by the invention]
However, when realizing an additional service such as a hold or transfer service, it is necessary to implement transfer means on the IP-PBX side on the premise of such a standard protocol. Also, depending on the connected device, there are cases where the hold and transfer procedures are not implemented, so in many cases services such as hold and transfer cannot actually be provided.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a telephone exchange method, apparatus, and system for enabling an additional call control function such as a hold transfer service in a telephone terminal controlled by an exchange regardless of a call control protocol implemented in the other party's telephone terminal. Is to provide.
[0007]
[Means for Solving the Problems]
A telephone exchange method according to the present invention is an IP telephone exchange method for establishing a connection between a plurality of telephone terminals each belonging to at least two networks operating by different protocols, and providing at least one relay address; In response to a call connection request between the telephone terminals, a call connection step of connecting each of the plurality of telephone terminals and the relay address with a corresponding protocol, and connection is made via the relay address A transfer table setting step for setting correspondence between addresses of a plurality of telephone terminals in a transfer table; and the transfer table after temporarily receiving a packet of a call signal transmitted from each of the plurality of telephone terminals at the relay address Based on the transfer destination address corresponding to the source address of the packet. A step, characterized in that it comprises a.
[0008]
The telephone exchange apparatus according to the present invention is an IP telephone exchange apparatus for establishing connection between a plurality of telephone terminals each belonging to at least two networks operating by different protocols, and means for providing at least one relay address; In response to a call connection request between the telephone terminals, a call connection means for connecting each of the plurality of telephone terminals and the relay address with a corresponding protocol is connected via the relay address. Transfer table setting means for setting correspondence between addresses of a plurality of telephone terminals in a transfer table; and the transfer table after temporarily receiving a packet of a call signal transmitted from each of the plurality of telephone terminals at the relay address And a transfer means for transmitting to a transfer destination address corresponding to the source address of the packet based on And wherein the Mukoto.
[0009]
The telephone exchange system according to the present invention includes an exchange that exchanges a plurality of telephone terminals belonging to a first network that operates under one protocol, and a second network that operates under a protocol different from the first network. A telephone switching system comprising a packet transfer device for establishing a connection between at least one telephone terminal belonging to the first network and at least one telephone terminal belonging to the first network. Means for establishing a call connection with a corresponding protocol between each of the telephone terminal of the first network and the telephone terminal of the second network and the relay address, and the packet forwarding apparatus includes at least one relay address and forwarding A table, and in cooperation with the exchange, the telephone terminals of the first network and the second network After the correspondence between each address of the talk terminal is set in the forwarding table and the packet of the call signal transmitted from each of the phone terminal of the first network and the phone terminal of the second network is once received at the relay address It has a means to transmit to the address of the forwarding destination corresponding to the address of the transmission origin of the said packet based on this forwarding table.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows the configuration of the entire system including a packet transfer apparatus 13 that implements the method according to the present invention. A plurality of local IP telephone terminals 10 a and 10 b are connected to a plurality of external IP telephone terminals 11 a and 11 b via a local IP network 14, IP-PBX 12 and IP network 15. A packet transfer device 13 is connected to the local IP network 14. The telephone exchange method, apparatus, and system according to the present invention are realized by the IP-PBX 12 and the packet transfer apparatus 13.
[0011]
Each of the plurality of local IP telephone terminals 10a and 10b and the plurality of external IP telephone terminals 11a and 11b implements a telephone call using VoIP (Voice over Internet Protocol) technology. VoIP is a general term for technologies and services for performing voice calls in an IP network, and the core of the technology is a call control protocol that is a series of control procedures for establishing, maintaining and releasing a communication path for a telephone. , Voice coding technology consisting of decoding that performs voice coding of voice packets suitable for IP networks and vice versa, and communication quality to maintain good voice quality despite packet delay or loss It consists of technology. Various protocols can be used as a call control protocol in VoIP.
[0012]
In the present embodiment, the plurality of external IP telephone terminals 11a and 11b are standard terminals capable of making VoIP telephone calls in a normal IP network, for example, an IP network such as the Internet. Protocols such as H.323 protocol, SIP (Session Initiation Protocol) protocol defined by IETF (RFC2543), and MGCP (Media Gateway Control Protocol) protocol proposed by IETF (RFC2705) can be used.
[0013]
The plurality of local IP telephone terminals 10 a and 10 b are terminals connected to the IP-PBX 12 via the local IP network 14 and controlled by a unique protocol that depends on the IP-PBX 12. The unique protocol is the above-mentioned H.264 protocol. Based on the H.323 protocol, the SIP protocol, or the MGCP protocol, a protocol in which call control information or a procedure is added or changed thereto, or a completely unique protocol may be used. In this sense, the plurality of local IP telephone terminals 10a and 10b and the plurality of external IP telephone terminals 11a and 11b are controlled by different protocols.
[0014]
In FIG. 1, only two local IP telephone terminals 10a and 10b and two external IP telephone terminals 11a and 11b are shown for ease of explanation. However, the method and apparatus according to the present invention is not limited to a large number of IP telephones. The form which accommodates a terminal is assumed.
The IP-PBX 12 is a private branch exchange that can accommodate a plurality of extension telephones, and has a function of realizing switching and exchange of packets in VoIP communication in software. The IP-PBX 12 in this embodiment uses a unique protocol different from the standard protocol for the plurality of local IP telephone terminals 10a to 10b and the packet transfer apparatus 13 to the plurality of local IP telephone terminals 10a to 10b. And provide transfer and hold service functions. The standard protocol or the original protocol is a protocol located in the application layer in the network layer, and uses UDP (User Datagram Protocol) / TCP (Transmission Control Protocol) protocol located in the network layer as a lower protocol for call control. The exchange of voice packets is performed using an RTP (Realtime Transport Protocol) protocol located in the upper layer of UDP. Therefore, in the following description, a communication packet at the time of exchanging voice signals for a call will be referred to as an RTP packet. A packet according to the RTP protocol is a packet suitable for transmission / reception of image or sound data by including its transmission time and order information, but does not include address information such as an IP address. This is because address information such as destinations for transmission and reception of RTP packets is included in the header of an IP packet in which the RTP packet is further packetized.
[0015]
In addition, by connecting the IP-PBX 12 to a normal public telephone line network (not shown), normal IP telephone terminals 10a and 10b and external IP telephone terminals 11a and 11b are connected to the public telephone line network. It is also possible to make a call with a telephone.
The packet transfer device 13 includes a transmission / reception unit 131, a transfer processing unit 133, a music on hold sound source 134, a transfer table 135, and an instruction receiving unit 136. The packet transfer device 13 is assigned a relay address (for example, an IP address C, which will be described later) for packet transfer for each call connection request, and once the voice signal packet is received via this relay address, an appropriate one is received. Transferred to the destination. The packet transfer device 13 can be realized by ordinary computer hardware preferably called a general terminal adapter.
[0016]
The transmission / reception unit 131 of the packet transfer apparatus 13 is connected to the local IP network 14 and performs transmission / reception of packets using a physical layer communication method such as Ethernet (registered trademark) using the IP protocol in the network layer.
The transfer processing unit 133 of the packet transfer apparatus 13 transfers a packet received from each of the local IP telephone terminals 10a and 10b and the external IP telephone terminals 11a and 11b directly or via the IP-PBX 12 in the transfer table 135. It has a function of transferring to any one of the previous IP telephone terminals 10a and 10b and the external IP telephone terminals 11a and 11b. In addition, when the transfer destination indicated in the transfer table 135 instructs the packet to be discarded, the transfer processing unit 133 instructs to discard the packet, and the designation of the transmission source in the transfer table 135 instructs the transmission of the hold sound. In such a case, it has a function of transmitting a voice packet of a holding tone to any of the corresponding external IP telephone terminals 11a and 11b.
[0017]
The hold tone sound source 134 of the packet transfer apparatus 13 holds a hold tone to be sent to a telephone on which a call is put on hold in a transfer / hold service, for example, in the form of an FM signal or a PCM signal, and a transfer processing unit 133. Has a function of outputting in response to the instruction.
The instruction receiving unit 136 of the packet transfer device 13 has a function of rewriting and updating the transfer table 135 as described above based on a transfer instruction from the IP-PBX 12 or a hold sound transmission instruction. The command message of the transfer instruction and the hold sound transmission instruction is transmitted by, for example, a UDP packet.
[0018]
The transfer table 135 of the packet transfer apparatus 13 associates the source of the packet transferred by the transfer processing unit 133 with the transfer destination. Here, referring to FIG. 2, one example of the forwarding table 135 is shown. In the example of the figure, IP address B is set as the transfer destination for IP address A as the source. As a result, the packet received from the IP telephone terminal having the IP address A is transferred to the IP telephone terminal having the IP address B by the transfer processing unit 133. Further, in the example of the figure, a dummy address indicated by “packet discard” is associated with the IP address B of the transmission source as a transfer destination. In accordance with this instruction, the packet received from the IP telephone terminal having the IP address B is discarded by the transfer processing unit 133 and is not transferred to any IP telephone terminal. On the other hand, IP address A is set as a transfer destination with a dummy address indicating “send hold sound transmission” as a source. As a result, the transfer processing unit 133 transfers, that is, sends out the hold sound packet from the hold sound source 134 to the IP telephone terminal with the IP address A. As the dummy address, it is conceivable to assign an IP address that is not assigned in operation, for example, a value such as “224.0.0.0”. In addition, the instruction form of packet discard and hold sound transmission using the transfer table 135 is one example, and there can be various methods.
<Explanation of operation at the time of outgoing IP phone terminal 10a>
FIG. 3 shows a processing procedure when a local IP telephone terminal makes a call in accordance with a protocol of the original specification. Here, it is assumed that the IP address A is assigned to the local IP telephone terminal 10a, the IP address C is assigned to the packet transfer apparatus 13, and the IP address B is assigned to the external IP telephone terminal 11a.
[0019]
First, the local IP telephone terminal 10a performs a call operation to the standard IP telephone 11b toward the IP-PBX 12 (step S11). In response to this, the IP-PBX 12 performs a call operation to the external IP telephone terminal 11a (step S12). The call operation transmits a call message according to a standard protocol corresponding to the external IP telephone terminal 11a. When the IP-PBX 12 edits this message, the IP address of the transmission source is set to the IP address of the packet transfer device 13, that is, the IP address C.
[0020]
In response to this, the external IP telephone terminal 11b calls (step S13). On the other hand, the IP-PBX 12 issues a ringing tone transmission instruction to the local IP telephone terminal 10a (step S14), and the local IP telephone terminal 10a reproduces the ringing tone.
In response to this call, the external IP telephone terminal 11a responds (step S15). In this case, the IP address C is set as the IP address of the response partner. In response to the response from the external IP telephone terminal 11a, the IP-PBX 12 transfers the packet from the IP address of the external IP telephone terminal 11a to the packet transfer apparatus 13 to the IP address of the local IP telephone terminal 10a. The packet from the IP address of the terminal 10a is instructed to be transferred to the IP address of the external IP telephone terminal 11a (step S16).
[0021]
In response to this instruction, the packet transfer apparatus 13 sets the transfer table 135 (step S17). That is, the IP address A and the IP address B are set to correspond to each other. Next, the IP-PBX 12 issues a voice transmission / reception instruction to the local IP telephone terminal 10a with the IP address C as the IP address of the voice transmission / reception partner (step S18). As a result, a speech path is set between the local IP telephone terminal 10a and the external IP telephone terminal 11a, and the packet transfer device 13 transmits an RTP packet of a speech signal between the local IP telephone terminal 10a and the external IP telephone terminal 11a. The packet transfer process is executed (step S19).
[0022]
Through the above processing procedure, the IP addresses of the other party of the local IP telephone terminal 10a and the external IP telephone terminal 11a are set to the IP address of the packet transfer device 13 (that is, IP address C), and apparently the local IP telephone terminal 10a. And the external IP telephone terminal 11a is the packet transfer device 13, and the packet transfer device 13 transfers the RTP packet of the call signal between the two, so that the local IP telephone terminal 10a and the external IP telephone terminal 11a can communicate with each other. A call is established.
<Description of the operation when the local IP telephone terminal 10a is received>
FIG. 4 shows a processing procedure when an incoming call is made to a local IP telephone terminal in accordance with a proprietary protocol. Here, it is assumed that the IP address A is assigned to the local IP telephone terminal 10a, the IP address C is assigned to the packet transfer apparatus 13, and the IP address B is assigned to the external IP telephone terminal 11a.
[0023]
First, the external IP telephone terminal 11a makes a call (step S21). At this time, the IP address B is set as the source IP address. Next, in response to the call operation, the IP-PBX 12 issues a ringing sound transmission instruction to the local IP telephone terminal 10a (step S22). In parallel, the IP-PBX 12 notifies the external IP telephone terminal 11a that the called party is being called (step S23).
[0024]
The IP-PBX 12 transmits a response message to the external IP phone terminal 11a (step S25) in response to the operator's response operation in response to the ringing sound transmitted from the local IP phone terminal 10a (step S24). This response message is a message in accordance with a standard protocol corresponding to the external IP telephone terminal 11a, and notifies the IP address of the response source (that is, the IP address of the called party) as the IP address C of the packet transfer device 13. .
[0025]
Next, the IP-PBX 12 instructs the packet transfer device 13 to transfer a packet (step S26). The IP-PBX 12 sends a packet from the IP address of the external IP telephone terminal 11a to the IP address of the local IP telephone terminal 10a, while a packet from the IP address of the local IP telephone terminal 10a is external IP. An instruction is given to transfer to the IP address of the telephone terminal 11a.
[0026]
In accordance with this instruction, the local IP telephone terminal 10a sets the forwarding table 135 (step S27). That is, IP address A and IP address B are associated with each other. Next, the IP-PBX 12 issues a voice transmission / reception instruction to the local IP telephone terminal 10a (step S28). At this time, the IP-PBX 12 instructs the local IP telephone terminal 10a as the destination IP address of the voice packet as the IP address of the packet transfer device 13, that is, the IP address C.
[0027]
Thereby, the packet transfer apparatus 13 performs packet transfer processing of the packet between the external IP telephone terminal 11a and the external IP telephone terminal 11a (step S29).
Through the above processing procedure, the IP addresses of the other party of the local IP telephone terminal 10a and the external IP telephone terminal 11a are set to the IP address of the packet transfer device 13 (that is, IP address C), and apparently the local IP telephone terminal 10a. And the external IP telephone terminal 11a is the packet transfer device 13, and the packet transfer device 13 transfers the RTP packet of the call signal between the two, so that the local IP telephone terminal 10a and the external IP telephone terminal 11a can communicate with each other. A call is established.
<Explanation of operation at the time of on-premises IP phone terminal 10a hold operation>
FIG. 5 shows a processing procedure in a case where a private IP telephone terminal according to a proprietary protocol holds a connected call.
[0028]
Since the packet transfer device 13 performs packet transfer processing of packets (step S31), a speech path is set between the local IP telephone terminal 10a and the external IP telephone terminal 11a. Here, the local IP telephone terminal 10a performs a hold operation (step S32).
In response to this, the IP-PBX 12 issues a packet transfer stop instruction to the packet transfer apparatus 13. In this case, the association between the IP address A and the IP address B is set to be deleted. Next, the dummy address of the hold sound instruction and the IP address B are set in association with each other as the hold delivery instruction (step S33). Next, the IP-PBX 12 instructs the local IP telephone terminal 10a to stop RTP transmission / reception (step S34).
[0029]
Then, the packet transfer device 13 receives the voice packet from the external IP telephone terminal 11a, but discards the received packet that is the voice packet (step S35). In parallel, a holding tone is sent to the external IP telephone terminal 11a (step S36).
The external IP telephone terminal 11a that receives the voice packet of the hold tone receives the hold tone while keeping the call state during a call (step S37).
[0030]
In the above processing procedure, the IP-PBX 12 instructs the packet transfer apparatus 13 to stop the previous packet transfer, and transmits the hold sound voice packet to the external IP telephone terminal 11a to be kept on hold. On the other hand, the local IP telephone terminal 10a is instructed to stop transmission / reception of RTP packets. As a result, the call state of the external IP telephone terminal 11a is listened to the hold sound while the call is in progress, and is apparently put on hold.
<Explanation of operation at the time of transfer operation on the local IP telephone terminal 10a>
FIG. 6 shows a processing procedure when a private IP telephone terminal in accordance with a proprietary protocol transfers a call that is currently connected to another IP telephone terminal after holding the call.
[0031]
Here, in the state where the local IP telephone terminal 10a performs a hold operation and the external IP telephone terminal 11a listens to the hold sound during a call between the local IP telephone terminal 10a and the external IP telephone terminal 11a, the local IP telephone terminal 10a A case where a call transfer operation is performed to another local IP telephone terminal 10b, that is, the local IP telephone terminal 10b having the IP address D is described.
[0032]
First, the packet transfer device 13 sends a hold sound to the external IP telephone terminal 11a (step S41). In response to this, the external IP telephone terminal 11a receives the hold tone while the call state is busy (step S42).
At this time, the local IP telephone terminal 10a performs a call transfer operation by the operation of the operator (step S43). In response to this, the IP-PBX 12 instructs the packet transfer apparatus 13 to stop sending the hold sound, and instructs a new packet transfer (step S44). At this time, the IP-PBX 12 forwards the packet from the IP address of the external IP telephone terminal 11a to the IP address of the local IP telephone terminal 10b (that is, IP address D) to the packet transfer device 13, and the local IP The packet from the IP address of the telephone terminal 10b is instructed to be transferred to the IP address of the external IP telephone terminal 11a.
[0033]
Next, the IP-PBX 12 issues a voice transmission / reception instruction to the local IP telephone terminal 10b that is the transfer destination (step S45). At this time, the external IP telephone terminal 11b is instructed as the IP address (that is, IP address C) of the packet transfer device 13 as the IP address of the packet transfer device 13 for transmitting and receiving voice packets. Next, the packet transfer device 13 performs a packet transfer process of the RTP packet between the local IP telephone terminal 10b and the external IP telephone terminal 11a (step S46). As a result, a call path is set between the local IP telephone terminal 10b to which the call has been transferred and the external IP telephone terminal 11a while the call state is busy, and the call is resumed (step S47).
[0034]
According to the above processing procedure, the IP address of the other party of the external IP telephone terminal 11a is apparently always the packet transfer device 13, but the transfer table 135 is rewritten in response to the call transfer request. The packet transfer device 13 to be referred transfers the RTP packet between the local IP telephone terminal 10b to which the call has been transferred and the external IP telephone terminal 11a. The external IP telephone terminal 11a can benefit from such services without any call control related to call transfer.
[0035]
In the above embodiment, the call connection is set between each of the local IP telephone terminal and the external IP telephone terminal and the relay address of the packet transfer apparatus, and each address of the local IP telephone terminal and the external IP telephone terminal is set. Are associated in the forwarding table, and the forwarding path of the RTP packet is set. As a result, call control can be performed between the packet transfer apparatus and the local IP telephone terminal by unique control. Accordingly, the hold transfer service can be performed with the IP telephone terminal managed by the private branch exchange regardless of the call control protocol installed in the other party's IP telephone terminal.
[0036]
In the above description, the example of connecting a private IP telephone terminal network such as a company to an unspecified external IP telephone terminal network such as an Internet telephone has been described. The apparatus and the system can be applied to a mode for exchanging connections between a plurality of IP telephone terminals each belonging to a network operating according to a different call control protocol regardless of a premises or an external terminology.
[0037]
In the above description of the embodiment, an IP telephone terminal based on the IP protocol has been described as a telephone terminal. However, the present invention is not limited to such a telephone terminal, and a terminal is specified by an address in a packet data network. The present invention can also be applied to other forms in which a call signal is communicated in the form of the packet.
[0038]
【The invention's effect】
As described above, according to the telephone exchange method, apparatus, and system of the present invention, the hold transfer service is provided to the telephone terminal controlled by the local network exchange regardless of the call control protocol implemented in the other party's IP telephone terminal. It is possible to provide such an additional call control function.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an entire configuration including a packet transfer apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a setting example of a transfer table illustrated in FIG.
FIG. 3 is a sequence diagram showing a processing procedure when a local IP telephone terminal makes a call according to a unique protocol.
FIG. 4 is a sequence diagram showing a processing procedure when an incoming call is made to a local IP telephone terminal according to a unique protocol.
FIG. 5 is a sequence diagram showing a processing procedure when a local IP telephone terminal according to a unique protocol puts a connected call on hold.
FIG. 6 is a sequence diagram showing a processing procedure when a local IP telephone terminal according to a unique protocol transfers a call that is currently connected to another IP telephone terminal after holding the call.
[Brief description of symbols]
10a to 10b Local IP telephone terminal
11a to 11b External IP phone terminal
13 Packet transfer device
14 Local IP network
15 IP network
16 Public telephone network
135 Transfer table

Claims (9)

An IP telephone exchange method for establishing a connection between a plurality of telephone terminals each belonging to at least two networks operating by different protocols,
Providing at least one relay address;
In response to a call connection request between the plurality of telephone terminals, a call connection step of connecting each of the plurality of telephone terminals and the relay address with a corresponding protocol;
A transfer table setting step for setting a correspondence between addresses of a plurality of telephone terminals connected via the relay address in a transfer table;
A transfer step in which a packet of a call signal transmitted from each of the plurality of telephone terminals is once received at the relay address, and then transmitted to a transfer destination address corresponding to a source address of the packet based on the transfer table; ,
An IP telephone exchange method comprising: The holding sound transmitting step of transmitting a holding sound packet toward the other telephone terminal of the plurality in response to a holding request from one of the plurality of telephone terminals. The IP telephone exchange method according to 1. In response to a hold request from one of the plurality of telephone terminals, in response to a call transfer request to a transfer destination telephone terminal belonging to the same network as the one telephone terminal, the one telephone terminal in the transfer table 3. The telephone communication method according to claim 1, further comprising a call transfer step of transferring a call by changing the address of the call to the address of the transfer destination telephone terminal. At least one of the different protocols is SIP protocol, MGCP protocol or ITU-T recommendation H.264. The IP telephone exchange method according to any one of the preceding claims, characterized in that the protocol is based on H.323. 6. The IP telephone exchange method according to claim 1, wherein transmission / reception of packet data of the communication signal is performed based on an RTP protocol. An IP telephone exchange apparatus for establishing a connection between a plurality of telephone terminals each belonging to at least two networks operating by different protocols,
Means for providing at least one relay address;
In response to a call connection request between the plurality of telephone terminals, call connection means for connecting each of the plurality of telephone terminals and the relay address with a corresponding protocol;
Transfer table setting means for setting a correspondence between addresses of a plurality of telephone terminals connected via the relay address in a transfer table;
A transfer means for once transmitting a packet of a call signal transmitted from each of the plurality of telephone terminals at the relay address and then transmitting the packet to a transfer destination address corresponding to a source address of the packet based on the transfer table; ,
An IP telephone exchange apparatus comprising: The apparatus further comprises: a hold sound transmitting means for transmitting a hold sound packet toward the other telephone terminal of the plurality in response to a hold request from the one of the plurality of telephone terminals. 6. The IP telephone exchange device according to 6. In response to a hold request from one of the plurality of telephone terminals, in response to a call transfer request to a transfer destination telephone terminal belonging to the same network as the one telephone terminal, the one telephone terminal in the transfer table 8. The IP telephone exchange apparatus according to claim 6, further comprising call transfer means for transferring a call by changing the address of the call to the address of the transfer destination telephone terminal. An exchange for exchanging a plurality of telephone terminals belonging to a first network operating under one protocol, at least one telephone terminal belonging to a second network operating under a protocol different from the first network, and A telephone switching system comprising a packet transfer device for connection with at least one telephone terminal belonging to a first network,
The exchange has means for making a call connection with a corresponding protocol between each of the telephone terminal of the first network and the telephone terminal of the second network and the relay address in response to a call connection request,
The packet transfer apparatus includes at least one relay address and a transfer table, and the correspondence between addresses of the telephone terminal of the first network and the telephone terminal of the second network in cooperation with the switch is set in the transfer table. The address of the source of the packet is set based on the forwarding table after the packet of the call signal transmitted from each of the telephone terminal of the first network and the telephone terminal of the second network is once received at the relay address. A telephone exchange system comprising means for transmitting to a transfer destination address corresponding to.

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