JPH11252149A - Communication system and communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct line connection to an exchanging device quickly by preventing frequent occurrence of internet protocol IP packets in an internet protocol network. SOLUTION: In this communication system, when a voice communication equipment 46 receives an incoming call request signal 45, whether or not there is any idle exchange line among exchange lines 47-49 contained in its own device is confirmed, and when not idle, whether or not there is any exchange line among exchange lines contained in other voice communication devices 50, 54, 58 is managed and an incoming call request signal 63 is transferred to the voice communication equipment, for example, containing the idle line. The voice communication equipment 58 receiving the signal gives the incoming call request signal 63 to a privade branch exchange 24 by using an exchange line 59 not occupied, the signal is given to, e.g. a telephone set 26 from it and the private branch exchange 24 informs the voice communication equipment 58 of an incoming call reply signal and the incoming call reply signal 64 is given to the voice communication equipment 46 of the transfer source. The voice communication equipment 46 output the incoming call reply signal 64 to a network 12 and gives a reply notice to the voice communication equipment 44 of a caller side 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system and a communication device, and can be applied to, for example, voice communication, data communication, and video communication via an Internet protocol network.

[0002]

2. Description of the Related Art In recent years, communication using an Internet protocol network has become widespread. The Internet protocol used in this network is TCP (Transmission control protocol) used in the Internet.
ocol) / IP means the Internet Protocol (IP), and corresponds to the OSI (Open System Interconnection) network layer. Its contents define the communication between the gateways of the Internet or between the gateway and the host.

FIG. 2 shows a configuration example of a voice communication system 1 using an Internet protocol network.
In this figure, a system 1 originates a call from telephones 6 and 8 connected to a private branch exchange 4 on a calling side 2, and transmits a call from a voice communication device 10 via an Internet protocol network 12 to a private line via one of the voice communication devices on a receiving side 14. This is a system in which an exchange receives a call and a call is made with one of the telephones.

In this figure, for example, when an outgoing signal is output from telephone 6 to telephone 26, the private branch exchange
(PBX) 4 receives the transmission signal and gives it to the voice communication device 10. Before outputting the outgoing signal to the Internet protocol network 12, the voice communication device 10 accesses the connected address information storage device 30 and
Search for an address for any of the voice communication devices, and based on this address,
Output to 12.

At this time, for example, an incoming call request signal is first sent to the voice communication device 16. The voice communication device 16 that has received this signal can use the line 32 to make an incoming call to the private branch exchange 24 if the switching line 32 is free. However, when the line 32 is not vacant, the voice communication device 16 notifies the voice communication device 10 via the network 12 of a signal 33 indicating that a call cannot be received.

[0006] The voice communication device 10 is, in turn, a voice communication device 18.
, An incoming request signal 34 is issued. When the voice communication device 18 receives this, if the exchange line 35 is vacant, the voice communication device 18 uses the line 35 to make an incoming call to the private branch exchange 24. Responds to device 10. The voice communication device 10 issues an incoming call request signal 37 to the voice communication device 20 this time. Voice communication device that received this
When the exchange line 38 is vacant, the private network exchange 24 uses this line 38 to make an incoming call. If the line 38 is not vacant, the call response signal 39 is returned to the voice communication device 10.

[0007] The voice communication device 10 issues an incoming call request signal 40 to the voice communication device 22 this time. Upon receiving this, the voice communication device 22 checks whether the switching line 41 is free, and if it is free, uses the line 41 to switch the private branch exchange 24
A call is received and a line connection with the telephone 26 is established to realize a telephone call. If the line 41 is not free, a call rejection signal 42 is returned to the voice communication device 10.

[0008]

When the private branch exchange 4 issues an incoming call request, the voice communication apparatus 10 of the calling side 2 sequentially proceeds to the receiving side 14 until a vacant exchange line is found as described above. To the voice communication devices 16, 18, 20, and 22. Therefore, when there are many calls during a call between the voice communication device on the receiving side 14 and the private branch exchange 24, the delay of the call connection is increased. Also, the number of voice communication devices accommodated by the private branch exchange 24 increases,
As the number of voice communication devices on the calling side increases and the scale of the system increases, the volume of calls increases and the delay in call connection increases more and more.

Further, as shown in FIG. 2, an Internet protocol packet (call request signal 31, 34, 37, 40, call impossible signal) for call connection transferred within the system.
33, 36, 39, and 42) occur frequently in the network 12 and affect other communications, for example, causing a delay.

[0010] For this reason, a plurality of communication devices are connected to the switching device, and these communication devices receive an incoming request signal from the Internet protocol network, search for a free line, and prevent frequent occurrence of IP packets in the network. Therefore, there is a demand for a communication system and a communication device that can quickly perform a line connection with a switching device.

[0011]

Therefore, according to the present invention, a communication device is connected to each of a plurality of lines accommodated by a switching device, and these communication devices receive an incoming call request for communication from an Internet protocol network. In a communication system that receives a signal, searches for a free line and connects the line to a switching device, a local area network is formed between a plurality of communication devices, and each communication device is for accommodating a line, And communication control means for communicating with the switching device, management means for managing the occupation state of the line used by the own device and other communication devices, and, upon receiving an incoming request signal, based on the request signal, Because the line is connected, whether the line connected from the own device to the switching device is free or not, and whether the line connected to another communication device is free Confirmation means for referring to the management means, and as a result of this confirmation, if the line connected to the own device is vacant, the communication control means makes a call to the exchange using the line. Control means for transferring an incoming request signal to another communication device when a line connected to the own device is not available and a line connected to another communication device is free. .

With such a configuration, the communication device can be applied to, for example, a voice communication device, a data communication device, and a video communication device. Each communication device manages whether a line with a switching device accommodated in another communication device is free (occupied) or not, and furthermore, a line accommodated in its own device is managed. Whether or not it is empty is also managed. Since the state of the free line of other communication devices is formed in the local area network (LAN) between the communication devices, it is easy to obtain the line free information from other communication devices using this LAN. Can be obtained.

[0013] Therefore, when an incoming call request signal is given from the network, it is possible to immediately recognize a free line in its own device and another communication device. If the line accommodated in the own device is not free, the other communication device can immediately recognize the free line and transfer the incoming request signal to the communication device using the LAN. it can.

The other communication device to which the incoming request signal has been transferred from the communication device may be configured so that the checking means checks the available line and the control means transmits the signal. When the other communication device receives the response signal for receiving the incoming call from the switching device after transmitting and outputting to the free line, the other communication device gives an incoming response signal to the transfer source communication device, and the communication device transmits the incoming response signal to the network. It may be configured to notify a response to the request.

Further, when a plurality of lines are connected between each communication device and the switching device, the delay of the call connection is further reduced, the use status of these lines is managed, and the confirmation means is free. The line may be confirmed, and the control means may make a call to any of the vacant lines, and if not, transfer to another communication device. In order to realize this, specifically, the communication device includes an address management unit that manages an Internet protocol address of the own device and another communication device, and the control unit transfers an incoming request signal to another communication device. Sometimes transfer is performed with reference to the address management means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the drawings. In this embodiment, an example in which the present invention is applied to a voice communication system will be described first. Therefore, in the present embodiment, a plurality of voice communication devices are connected to a plurality of lines accommodated by the private branch exchange, and these voice communication devices receive an incoming request signal for voice communication from the Internet protocol network and search for a free line. A description will be given of a voice communication system for performing line connection with a private branch exchange.

FIG. 1 is a diagram showing a configuration example of a voice communication system 43 according to the present embodiment. In this figure, the same parts as those in FIG. In FIG. 1, when a voice communication device 44 receives an outgoing signal transmitted from the private branch exchange 4 by the telephone 6, the address information storage device 30 obtains, for example, an IP address for the voice communication device 46, and transmits an incoming request signal 45. Send to network 12.

The voice communication device 46 manages in advance whether any of the switching lines 47 to 49 accommodated in the own device is vacant (empty / occupied state), and accommodates in another voice communication device 50. Vacant lines such as the exchange lines 51-53, the exchange lines 55-57 accommodated in the voice communication device 54, and the exchange lines 59-61 accommodated in the audio communication device 58 are managed. The occupation status of the switching line in the own device is determined by other voice communication devices.
Notify 50, 54, 58.

In order to perform such management, the voice communication devices 46, 50, 54, and 58 form one local area network 62 (for example, Ethernet LAN), and a signal between the voice communication devices. Is configured to be easily exchanged. For example, the status of the vacant switching line of another voice communication device, the transfer of an incoming request signal to another voice communication device, and the like can be immediately executed by the LAN. Since it can be transferred to another voice communication device without returning it to the voice communication device 44 of the calling side 2 via the network 12 as in the prior art, it can be transferred quickly, and there is no need to establish a path to the network 12 for the transfer. Time can be reduced.

The voice communication device 50 also manages in advance which of the switching lines 51 to 53 accommodated in its own device is vacant, and determines whether the switching line accommodated in another voice communication device is free. It manages which is free. Then, the occupation status in the own device is determined by the other voice communication devices 46, 54, 58.
Notify to The voice communication device 54 also manages in advance whether any of the switching lines 55 to 57 accommodated in its own device is vacant, and any of the switching lines accommodated in other voice communication devices is vacant. Is managing. Then, the occupation status within the own device is determined by the other voice communication device 4.
Notify 6, 50, 58. The voice communication device 58 also manages in advance whether any of the switching lines 59 to 61 accommodated in its own device is vacant, and any of the switching lines accommodated in other voice communication devices is vacant. It manages whether or not it is. Then, the occupation status in the own device is notified to the other voice communication devices 46, 50, 54.

The voice communication devices 46, 50, 54, 58 may be configured to be incorporated in a gateway device, a hub (HUB) device (an intelligent hub, a smart hub, a switching hub, etc.). In addition, the voice communication devices 46 and 5
One of the lines 0, 54, and 58 is always open for emergency priority, and normally, another voice communication device is used. When an incoming call request signal indicating an emergency is given, the emergency priority is given. May be received by a voice communication device for communication.

Next, the operation of the voice communication system shown in FIG. 1 will be described. For example, the telephone 6 outputs a call signal for making a telephone call to the telephone 26 via the voice communication device 46,
When given to the private branch exchange 44, the private branch exchange 44 accesses the address information storage device 30 based on the destination of the outgoing signal to obtain an Internet protocol address, and sends an incoming request signal 45 to the Internet protocol network 12.

The incoming call request signal 45 is transmitted to, for example, a voice communication device.
When 46 receives it, the switching lines 47-
Check if any of the 49 is occupied by communication,
If any of them is vacant, the private branch exchange 24 is terminated using the exchange line. However, if none of the switched lines is free, the other voice communication devices 50, 54, 58 notify the LAN of a signal indicating the occupation status of the switched line,
Check if there is an unoccupied switched line. In this confirmation, for example, when it is confirmed that the switching line 59 of the voice communication device 58 is vacant, the voice communication device 46 transfers the incoming call request signal 63 to the voice communication device 58 through the LAN.

When the voice communication device 58 receives the transferred incoming call request signal 63, the voice communication device 58 gives it to the private branch exchange 59 using, for example, a line 59 as a vacant exchange line. Can be notified to the voice communication device 58 and the telephone 26 can receive a call. The voice communication device 58 notifies the transfer source voice communication device 46 of the incoming response signal 64 via the LAN. The voice communication device 46 that has received the incoming response signal 64
65 is output to the network 12 and the voice communication device 44 of the transmitting side 2 is output.
Notify.

With the above operation, the network
The transmission and reception of the Internet protocol packet in the communication device 12 is reduced as compared with the related art, and the process of establishing a path between the voice communication devices of the transmitting side 2 and the receiving side 14 via the network 12 is simplified. And the delay of the call connection is short,
Even if the switching line accommodated in the voice communication device 46 is not vacant as in the above-described example, the other voice communication devices 50, 54, 58
Since the line occupation status of the line is managed, the incoming call can be received by a single transfer from the voice communication device 46 to the voice communication device 58 having a free line.

In the example of FIG. 1 described above, the private branch exchange 24,
Although the example in which the voice communication device is connected to the switch 44 via the switching line, the present invention can be applied not only to the private branch exchange but also to a switching device of a telephone station of a public telephone network.
In addition to the incoming request based on the outgoing signals from the telephones 6 and 8, the incoming request transmitted from the personal computer 7 that can make outgoing calls is received by the personal computer 27 of the receiving side 14, and the line is connected. It can also be used to perform personal computer communication and video communication. It should be noted that not only a personal computer but also other image terminals such as facsimile machines, voice terminals, and data terminals can be connected and used. From these facts, the present invention can be widely applied not only to a voice communication system but also to a system that performs communication through an Internet protocol network in a broad sense.

Next, a specific configuration of an example of the voice communication device shown in FIG. 1 will be described with reference to FIG. The voice communication devices 46, 50, 54, 58 shown in FIG.
This is a common configuration for The above-described operation can be realized by providing a part of the configuration in FIG. 3 for the voice communication device 44 on the transmitting side in FIG.

The voice communication device performs an execution control process of voice communication (reception of an incoming request signal, transmission to a private branch exchange, transfer control to another voice communication device, reception of an incoming response signal, etc.). And the occupation status of the switching line in the own device,
The data circuit 70 stores data such as the occupation state of the switched lines of other voice communication devices in the group forming the LAN and the address of the other voice communication devices forming the LAN. It is configured. It may be realized by a hardware circuit or a software function unit.

When receiving the incoming call request signal 45, the LAN communication control circuit 72 of the execution circuit 68 refers to the resource management data circuit 74 to determine whether there is a PBX communication control circuit and a switching line not used in its own device. A reference signal 76 is provided to obtain vacant PBX communication control circuit and switched line data. When this data is obtained, the outgoing signal 86 is vacant
At the same time as giving to any of the PBX communication control circuits 78, 80, and 82, a signal 84 for setting the PBX communication control circuit to use reservation to the use reservation state is given to the resource management data circuit 74 and set. The LAN communication control circuit 72 is
Upon receiving a signal 92 indicating a response to the reception of the incoming call from 8, 80, 82, it returns an incoming response signal 97 to the calling side, and at the same time,
The resource management data circuit 74 is given a signal 84 for setting that the PBX communication control circuit to be used is occupied, and is managed.

Further, the LAN communication control circuit 72 gives the exchange control circuit 94 an instruction signal 96 for notifying another voice communication device that the resource state has changed. Further, when the incoming request signal 45 is received from the network, the resource management data circuit 74 is checked, and if the PBX communication control circuits 78, 80, and 82 in the own device are managed as communicating, An instruction signal 112 for instructing transfer to another voice communication device in the group is given to the transfer control circuit 110. Further, upon receiving the incoming response signal 122 from the transfer control circuit 110, the LAN communication control circuit 72 returns an incoming response signal 97 to the voice communication device on the transmitting side.

The PBX communication control circuits 78, 80, and 82 are circuits having the same function in all three circuits. When a signal 86 for instructing transmission is given, a PBX communication control circuit 78, 80, and 82 outputs a transmission signal 88 to a switched line and is supplied from the switched line. When receiving the incoming call response signal 90, LA
N An incoming response signal 92 is given to the communication control circuit 72. In addition, in the present invention, a case where a plurality of switched lines are accommodated or a case where one switched line is accommodated is also applicable in principle. Therefore, when accommodating one line, one PBX communication control circuit is also provided. That is fine.

The resource management data circuit 74 becomes vacant when the LAN communication control circuit 72 is supplied with a reference signal 76 for referencing whether or not there is a PBX communication control circuit and a switched line which are not used in its own device. The PBX communication control circuit and the switched line data are read out and the LAN communication control circuit 72 is read.
Give to. Further, when the resource management data circuit 74 is given a signal 84 for setting a certain PBX communication control circuit and a switched line to the use reservation state from the LAN communication control circuit 72, the resource management data circuit 74 makes this reservation setting, and thereafter, after receiving the incoming call response, Change the setting from the use reservation state to the busy state.

Further, when the contents of the data managed by the change of the line occupation state in its own device are changed, the resource management data circuit 74 exchanges the data 98 of the resource state (line occupation state) with the exchange control circuit 94. Give to. The resource management data circuit 74 stores the data 108 of the resource state (line occupation state) of another voice communication apparatus when given from the switching control circuit 94. In addition, the resource management data circuit
74 supplies the data 114 of the device having an empty line among the lines accommodated in other voice communication devices to the intra-group transfer control circuit 110.

When the exchange control circuit 94 receives an instruction signal 96 from the LAN communication control circuit 72 to notify another voice communication device that the resource status has changed, the resource control data circuit 74 sends the resource control data circuit 74 its own resource. Status (line occupancy status)
Of the member address information circuit 10
Fetch the IP address 102 of another voice communication device from 0,
The other voice communication device is notified of data 104 of its own resource status (line occupancy status). When the switching control circuit 94 takes in the data 106 of the resource status (line occupation status) from another voice communication device, the switching control circuit 94 converts the data 108 of the resource status (line occupancy status) of the other voice communication device into the resource management data circuit 74. To update the storage state.

The member address information circuit 100 stores all the IP addresses of the other voice communication devices, and gives the exchange control circuit 94 and the transfer control circuit 110 the IP addresses 102 and 106 as necessary.

The transfer control circuit 110 first sends an instruction signal 112 for instructing transfer to another voice communication device in the group in order to transfer to another voice communication device when there is no free line in the device itself. When received from the LAN communication control circuit 72, the data 114 of a device having an empty line among the lines accommodated in other voice communication devices is transmitted to the resource management data circuit.
From the member address information circuit 100, the IP address 106 of the device having a free line is obtained from the member address information circuit 100, and the incoming request signal 118 is transferred and output. When a call connection is made by another voice communication device and a response signal for receiving an incoming call is received, and when this incoming response signal 120 is given, an incoming response signal 122 is given to the LAN communication control circuit 72.

Next, the operation of the voice communication apparatus shown in FIG. 3 will be described. First, the LAN communication control circuit 72 sends the incoming request signal 45
Is received, a reference signal 76 is given to the intra-group resource management data circuit 74 to determine whether or not the switching line accommodated in the own device is communicating in the PBX communication control circuits 78, 80, and 82. If any of them is vacant, for example, a signal 84 for setting the PBX communication control circuit 78 and the switching line 47 to the use reservation state is given to the intra-group resource management data circuit 74. The LAN communication control circuit 72 gives a signal 86 for instructing the PBX communication control circuit 78 to make a call.

The PBX communication control circuit 78 receiving this signal 86
Outputs the outgoing signal 88 to the switching line 47 and gives it to the private branch exchange 24. Next, an incoming response signal 90 indicating connection completion is given from the private branch exchange 24 to the PBX communication control circuit 78. The PBX communication control circuit 78 notifies the LAN communication control circuit 72 of the incoming response signal 92. The LAN communication control circuit 72 provides the PBX communication control circuit 78 and the switching line 47 to the resource management data circuit 74.
Is instructed by the signal 84 to change the setting from the use reservation state to the busy state. Then, the management state of the resource management data circuit 74 is changed. LAN at the same time
The communication control circuit 72 gives the exchange control circuit 94 an instruction signal 96 for notifying the other voice communication device that the resource state has changed, and also provides the calling side voice communication device with an incoming call reception. The response signal 97 is returned.

Thus, the switching control circuit 94 reads and takes in the data 98 of the resource state (line occupation state) of its own device from the resource management data circuit 74, and reads all voices in the group from the member address information circuit 100. Read and capture the IP address 102 of the communication device,
It notifies the voice communication devices in the group of data 104 of its own resource status (line occupation status).

The switching control circuit 94 also takes in data 106 of the resource status (line occupation status) from other voice communication devices in the group. As a result, the exchange control circuit 94
The data 108 of the resource status (line occupation status) of another voice communication device is supplied to the resource management data circuit 74 to update the storage status.

On the other hand, when receiving the incoming call request signal 45 from the network 12, the LAN communication control circuit 72 checks the resource management data circuit 74, and the PBX communication control circuits 78, 80, and 82 in its own device perform communication. If it is managed as being in the middle, an instruction signal 112 for instructing transfer to another voice communication device in the group is given to the transfer control circuit 110. Then, the transfer control circuit 110 refers to the resource management data circuit 74 to obtain data 114 of a device having a free line among the lines accommodated in other voice communication devices, and From the member address information circuit 100. And this IP address 10
Based on 6, the call request signal 118 is transferred to another voice communication device and output.

When another voice communication apparatus receiving this call request signal 118 receives a call to the private branch exchange using a free line, a call connection is made, a call reception response signal is received, and the call response signal 120 is received. Is received by the transfer control circuit 110. The transfer control circuit 110 is connected to the LAN communication control circuit 7
2 is given an incoming response signal 122. LAN communication control circuit 72 returns incoming response signal 97 to the voice communication device on the transmitting side.

When an incoming call request signal is given from the network by the above-described operation, if the exchange line accommodated in the own device is vacant, the call is transmitted to the line side by using that line. It also manages the use status of the lines accommodated in other voice communication devices obtained through the LAN, so if there is no free line in the own device, other voice communication The incoming call request signal can be transferred to the device and can be received by the switched line. Therefore, a call can be received by one transfer, and the delay of the call connection is reduced.

The PBX communication control circuits 78, 80, 82
N It can be occupied in sequence by a signal from the communication control circuit 72, or one can be kept free at all times for use for the emergency
A communication control circuit may be used. FIG.
3 can be easily realized by providing at least the LAN communication control circuit 72 and the PBX communication control circuit 78 in the configuration shown in FIG.

[0045]

As described above, the present invention relates to a communication apparatus for receiving an incoming request signal from an Internet protocol network and outputting the signal to a switching line.
Check whether the exchange line accommodated in the own device is vacant, if not, determine whether the exchange line accommodated in any device of the other communication device is vacant, Since the incoming request signal is transferred to the communication device that accommodates the vacant exchange line using the LAN between the devices, and the call is received from that device to the exchange device, it is possible to prevent the frequent occurrence of IP packets in the network. As a result, the line connection with the switching device can be quickly performed.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a configuration example of a voice communication system according to an embodiment of the present invention.

FIG. 2 is a diagram similar to FIG. 1, showing a configuration example of a conventional voice communication system.

FIG. 3 is a device configuration diagram showing a configuration of a specific example of the voice communication device shown in FIG. 1;

[Explanation of symbols]

 6, 8, 26, 28 Telephone 7, 27 Personal computer 4, 24 Private branch exchange 12 Internet protocol network 44, 46, 50, 54, 58 Voice communication device 47-49, 51-53, 55-57, 59-61 Line 62 Local Area Network (LAN)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04M 11/00 303 H04L 11/20 B H04Q 3/58 106

Claims (9)

[Claims] A communication device is connected to each of a plurality of lines accommodated by a switching device. The communication devices receive an incoming request signal for communication from an Internet protocol network, search for a vacant line, and search for a vacant line. In a communication system for performing line connection with a switching device, a local area network is formed between the plurality of communication devices, and each of the communication devices is for accommodating the line and performs communication with the switching device. Communication control means for performing communication, management means for managing the occupation state of the line used by the own device and other communication devices, and receiving the incoming request signal, connecting the line based on the request signal. Whether the line connected from the device to the switching device is free, and whether the line connected to another communication device is free. Confirmation means for confirming by referring to the management means, as a result of the confirmation, if the line connected to the own device is vacant, the communication control means uses the line to Control for making a call and transferring the incoming request signal to another communication device when the line connected to the own device is not available and the line connected to another communication device is free And a communication system. 2. The communication system according to claim 1, wherein the control unit performs communication for transferring the incoming call request signal using the local network.
A communication system including a (local area network) communication unit. 3. The communication system according to claim 1, wherein the other communication device to which the incoming request signal has been transferred from the communication device confirms a free line by the confirmation means and transmits the signal by the control means. A communication system characterized by performing: 4. The communication system according to claim 3, wherein the other communication device transmits and outputs the call to the idle line,
When receiving a response signal of the incoming call from the switching device,
A communication system, comprising: providing the incoming call response signal to the transfer source communication device; and the communication device notifying the Internet protocol network of the incoming call response signal. 5. The communication system according to claim 1, wherein a plurality of lines are connected between each of the communication devices and the switching device, and the management unit is configured to manage the plurality of lines. The use state is managed, wherein the confirmation unit confirms a vacant line, and the control unit transmits a call to any vacant line, and performs the transfer when it is not vacant. Communication system. 6. The communication system according to claim 1, wherein each of the communication devices includes an address management unit that manages Internet protocol addresses of the own device and another communication device, and the control unit includes: A communication system that performs the transfer by referring to the address management unit when transferring the incoming request signal to another communication device. 7. The communication system according to claim 1, wherein each of the communication devices receives an incoming call request signal for any of voice communication, data communication, and video communication. Communication system. 8. A communication device for receiving an incoming request signal for communication from the Internet protocol network side and outputting the signal to a switched line, wherein the device is for accommodating the switched line, and Communication control means for performing communication with the device, management means for receiving and managing a usage signal indicating the usage status of another switched line from another device and managing the usage status of the communication control means, Upon receiving the incoming request signal, refer to the management means to determine whether or not the communication control means is occupied and whether or not the other switched line is free for line connection based on the request signal. Confirmation means for confirming the communication control means, if the result of the confirmation indicates that the communication control means is not occupied, originates a call using the communication control means; If the replacement line is vacant, a communication apparatus characterized by comprising a control means for transferring and outputting the incoming request signal to give to other exchange lines. 9. The communication apparatus according to claim 8, wherein said control means includes a LAN (Local Area Network) communication unit for performing communication for transferring said incoming call request signal.