JP2000196675A - Method and device for controlling connection of communication network and communication system using them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently select and connect an IP-GW device at the time of setting a call by selecting a connectable interface device among plural interface devices at a connecting destination and connecting a communication network at the time of connecting a call of a first communication network to a first communication network at another base through a second communication network. SOLUTION: A call is originated from a telephone set 101 to an exchange 104 first. Next, the exchange 104 transmits a GW address request to an SIG-SV device 106 through a control light 105. The device 106 retrieves the IP address corresponding table of SIG-SV to obtain the IP address of the device 106 to transmit the GW address request. An exchange 114 makes a dead channel in a reserved state to obtain the IP address of a corresponding IP-GW device to transmit a GW address response to the device 116.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for relaying a call of a first communication network via a second communication network, and more particularly, for relaying a call of a circuit switching network via an IP network. Voice over IP (hereinafter abbreviated as VoIP)
The present invention relates to a communication network connection control method and a communication network connection control device in a technical field and a communication system using them.

[0002]

2. Description of the Related Art In the VoIP technology for relaying a call of a circuit switching network via an IP network, an exchange and an Internet protocol (hereinafter abbreviated as IP) which are connected to the exchange and compress the speech voice of the circuit switching network. Gateway device (hereinafter referred to as an IP-GW) that converts a call voice from an IP packet received via an IP
A plurality of sites having a plurality of devices (referred to as devices) are connected to each other via an IP network to form a communication network. Then, at each site, the IP-GW device interlocks with the call processing of the exchange,
At the time of call setup, the exchange at the partner site and the IP-GW device at the partner site are connected. Conventionally, a connection procedure between an exchange and an IP-GW device has been performed as follows. First, the IP-GW device analyzes the telephone number of the destination, checks the exchange at the base accommodating the terminal of the telephone number, obtains the IP address of the IP-GW device connected to the exchange, and communicates with the exchange. Connect the IP-GW device. The IP address of the IP-GW device is set in a form associated with the exchange in advance.
I search the correspondence table and find it.

[0003] By the way, with the increase of users, VoIP
Considering the case where the voice relay by using multiple lines is considered,
It is conceivable to configure a system by connecting a plurality of IP-GW devices to an exchange at one base. In such a system configuration, a plurality of IP addresses are described for one exchange in the correspondence table between the exchanges and the IP addresses. In the prior art, switching equipment and IP
-When connecting a GW device, first, a call setting is requested to the partner IP-GW device described first in the correspondence table. If the call setup is rejected because the communication line of the partner IP-GW device is in use, etc., the correspondence table is referred to again and the IP address of the second IP address described in the second table is referred to.
In such a manner as to request the P-GW device to set up the call again, the partner IP-GW device is selected according to the order described in the correspondence table, and the call setting is requested.

[0004] Other conventional techniques are described in Nikkei Communication, October 19, 1998, P.O. 122-
129, using a network for transmitting control signals called a common channel signaling network provided separately from a communication line.
control) and SGCP (simple gat)
destination control, using a protocol such as E.Way control protocol.
There is a method of selecting a GW device.

[0005]

In the above-mentioned conventional technology, when selecting an IP-GW device, a partner IP-GW device is selected.
No consideration is given to the line availability state of the GW device, and it is selected in order from the first IP-GW device according to the correspondence table,
Since re-calling is repeated until connection is established, there is a problem that when all the lines of the other party are busy, it takes a considerable amount of call processing time until it is determined that the connection cannot be established. This call processing time increases in proportion to the number of IP-GW devices installed in the system, and the larger the VoIP system, the lower the call processing efficiency.

[0006] In addition, the destination IP
-In the prior art for selecting a GW device, a large-scale VoIP
However, there is a problem that the load is concentrated on the centralized controller when trying to realize the above.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. Even when a single base is provided with a plurality of IP-GW devices, the IP-G of a connection partner can be efficiently set up at the time of call setup.
An object of the present invention is to provide a communication network connection control method and a communication network connection control device for selecting and connecting a W device, and a communication system using them.

[0008]

In order to achieve the above object, a communication network connection control method according to the present invention comprises a first communication network installed at a plurality of bases connected via a second communication network. ,
Each base is a connection control method between communication networks in a communication system having a plurality of interface devices for converting a call of a first communication network into a call of a second communication network, wherein the call of the first communication network is a first communication network. When connecting to the first communication network of another base via the second communication network, a connectable interface device is selected from a plurality of connection destination interface devices, and the communication network is connected. .

Further, in the communication network connection control device of the present invention, first communication networks installed at a plurality of bases are connected via a second communication network, and each base is connected to a call of the first communication network. Is a connection control device between communication networks in a communication system having a plurality of interface devices for converting a call to a call of a second communication network, wherein a call of the first communication network is transmitted to another base via the second communication network. When connecting to the first communication network, a connectable interface device is selected from a plurality of interface devices at each base, and control is performed to connect the communication network.

[0010]

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

First, the overall configuration of a system to which the present invention is applied will be described.

FIG. 1 is a diagram showing an example of the overall configuration of a system to which the present invention is applied.

In this embodiment, there are three bases, a base A provided with three IP-GW apparatuses, a base B provided with two IP-GW apparatuses, and a base C provided with four IP-GW apparatuses, connected by a router via an IP network. An example is shown.

At site A, telephones 101, 102, and 103 are connected to an exchange 104. A control device connected to the exchange 104 via a control line 105, which analyzes a telephone number of a called party received via the control line 105, and sends a control signal to the control device at the base corresponding to the telephone number. And a signaling server device 106 (hereinafter abbreviated as SIG-SV device) having means for inquiring about the IP address of an IP-GW device having a vacant connection line with the server. According to the present invention, such a SIG-SV is provided at each base, and the exchange 104
In response to the IP address request of the P-GW device, a vacant line is searched, the vacant line is reserved, and the corresponding I
It is characterized in that the IP address of the P-GW device is notified to the SIG-SV106 device. Exchange and IP-
The GW devices 107, 108, and 109 are PRI (Primary Rate Interface) which is an ISDN primary rate interface.
They are connected by a digital line 110 (hereinafter, referred to as a relay line) such as a line. Also, the SIG-SV device 106
And the three IP-GW devices 107, 108, and 109 are LA
N, and they are connected to an IP network via a router.

Similarly, at the location B, an exchange 114 and telephones 111, 112, 113 connected to the exchange are provided.
And a SIG-S connected to the exchange by a control line 115.
V-device 116 and IP-GW devices 117 and 118 connected to the exchange by a trunk line 119, and SIG-S
The V device 116 and the two IP-GW devices 117 and 118 are connected by a LAN and connected to an IP network via a router.

At the site C, an exchange 123, telephones 120, 121 and 122 connected to the exchange, and a SIG-SV 12 connected to the exchange via a control line 124 are connected.
5 and the IP-IP connected to the exchange via the trunk line 130.
GW devices 126, 127, 128, 129, and SI
G-SV device 125 and four IP-GW devices 126, 1
27, 128 and 129 are connected by a LAN and connected to an IP network via a router.

Here, the numbering plan of the communication network will be described by taking the system shown in FIG. 1 as an example.

FIG. 2 is a diagram showing an example of a communication network numbering plan in the present embodiment.

FIG. 2 shows an example 201 of a numbering plan in the system shown in FIG. This table shows the correspondence between the base 202, the base number 203 assigned to the base, and the telephone number 204 accommodated in each base.
And a telephone number 204. For example, when the telephone 101 at the site A talks with the telephone 112 at the site B, the telephone 101 designates the telephone number “8314502” as the called number and makes a call.

Next, the configuration of the SIG-SV device will be described with reference to FIGS.

FIG. 3 shows the site number and the I of the SIG-SV device.
It is a figure showing an example of a P address correspondence table.

FIG. 9 is a diagram showing the configuration of the SIG-SV in this embodiment.

As shown in FIG. 9, the SIG-SV device
CP for controlling the entire apparatus and executing the functions of the present invention
U901 and a memory 90 for holding the base number and SIG-SV device IP address correspondence table shown in FIG.
3, a memory controller 902 for controlling reading of memory contents, writing data to the memory, and the like;
It is composed of a LAN interface 905 connected to the LAN, a control line interface 904 connected to the exchange, and a bus 900 connecting these.

FIG. 3 shows the site number 302 and the SIG of each site.
-This is an example of a table 301 in which the IP addresses 303 of the SV devices are associated with each other.
The data is stored in the SV device in advance. Each SIG-
The SV device searches the table using the base number portion of the called number received from the exchange as a key, and searches for the corresponding destination SIG.
-Obtain the IP address of the SV device.

Next, the configuration of the exchange will be described with reference to FIGS.
This will be described with reference to FIGS. 7, 8, and 10.

FIG. 4 is a diagram showing an example of a correspondence table between the channel numbers of the trunk lines at the site B and the corresponding IP addresses of the IP-GWs in the embodiment.

FIG. 5 is a diagram showing an example of a trunk line idle state management table at the site B according to the present embodiment.

FIG. 7 is a diagram showing an example of the correspondence table between the channel numbers of the trunk lines at the site A and the IP addresses of the corresponding IP-GW devices in the present embodiment.

FIG. 8 is a diagram showing an example of the trunk line idle state management table at the site A according to the present embodiment.

FIG. 10 is a diagram showing the configuration of the exchange in this embodiment.

As shown in FIG. 10, the exchange in the present embodiment has a CPU 1002 for executing each function, a channel number of a trunk line and an address of a corresponding IP-GW apparatus as shown in FIGS. A memory 1004 for holding a table and a trunk line free state management table as shown in FIGS. 5 and 8, and a memory controller 1003 for controlling reading of the contents of the memory and writing of data to the memory. , A control line interface 1005 connected to the SIG-SV device, an extension interface 1006 connected to the telephone, a trunk line interface 1007 connected to the IP-GW device, a control bus 1000 connecting these, and an extension interface 100
6 and a trunk line interface 107.

FIG. 4 is a table previously stored as data in the exchanges at each site. The table shows the channel number 402 of the trunk line connecting the exchange and the IP-GW apparatus, and the IP-GW connected to the channel. Device IP address 4
03 is a table 401 associated with the information. Figure 4 shows location B
Is shown. Similarly, FIG. 7 is an example of the base A,
9 is a table 701 that associates a channel number 702 with an IP address 703.

FIG. 5 shows an example of a site B in the trunk line idle state management table 501 managed by the exchange at each site. The trunk line idle state management table includes a channel number 502, its state 503, and its own call ID5.
04 and the partner station call ID 505. The local station call ID 504 and the partner station call ID 505 are IDs used to uniquely identify which call is secured for the line in the connection sequence described with reference to FIG. 6, and are issued when processing of one call occurs. It is assumed that unique values are generated and used by the calling side and the called side, respectively. Similarly, FIG. 8 is an example of an empty state management table of the trunk line at the site A, and is a table 801 that associates the channel number 802, the state 803, the own station call ID 803, and the other station call ID 805.

Next, the operation of the present embodiment will be described with reference to FIGS. 6 and 11 to 19, showing a specific connection sequence and an example of a format of a message transmitted and received between the respective components.

FIG. 6 is a diagram showing a connection sequence between bases in this embodiment.

FIGS. 11, 12 and 13 show examples of the format of the GW address request message.

FIGS. 14, 15 and 16 show examples of the format of the GW address response message.

FIGS. 17, 18 and 19 show examples of the format of a call setup request message.

The sequence diagram shown in FIG. 6 shows a connection sequence until the telephone set 101 at the location A and the telephone set 112 at the location B start talking.

First, a call 601 is issued from the telephone set 101 to the exchange 104 to instruct the exchange number "8314502". The exchange 104 sets the vacant state of the trunk line of its own station to the reserved state with reference to the table 801 (FIG. 8) (in the example of FIG. 8, the channel number "3" is reserved), and its own station call ID. (In the example of FIG. 8, "call ID-1"
23 "), and the value is set in the column of own station call ID of channel number" 3 "in table 801 (650). Next, the exchange 104 connects the SIG-SV device 1 via the control line 105.
06, the called number "8314502" and the own station call ID "Call ID"
GW address request 602 including “−123” as a parameter
Send The message of the GW address request 602 at this time is, for example, a message format 1 as shown in FIG.
At 110, the control line transmission header, protocol ID, called number, and own station call ID are transmitted as parameters.

SIG receiving this GW address request
-The SV device 106 determines the base number part "831" of the called number.
Using the key as a key, the base number and the SIG-SV IP address correspondence table 301 stored in advance are searched, and the corresponding IP address “133.
144.2.10 "(651). The SIG-SV device 106 uses the IP address obtained here to
-The local station call ID "call ID-12"
GW address request 603 including "3" as a parameter is transmitted. The GW address request message 603 for the other party's SIG-SV device has, for example, a message format 1200 as shown in FIG. The GW address request message includes an IP header, a TCP header, and a protocol I.
D, the local station call ID, and other parameters.

SIG-SV device 116 receiving this
Sends the local call ID to the exchange 114 via the control line 115.
A GW address request 604 including “Call ID-123” as a parameter is transmitted. FIG. 13 shows a GW address request 604.
1300 is shown. GW address request message 6
04 transmits a control line transmission header, a protocol ID, and a local station call ID in a message format 1300 as shown in FIG.

The exchange 114, which has received the GW address request 604 from the SIG-SV device 116, checks the idle state of the trunk line with the IP-GW device with reference to the table 501 (FIG. 5). The vacant channel is set in a reservation state (in the example of FIG. 5, the channel number “2” is reserved), a local station call ID is generated (in the example of FIG. 5, “call ID-011”), and the channel of the table 501 is set. The value is set in the column of the own station call ID of the number “2”, and “call ID-123” received in the GW address request 604 is set as the partner station call ID in Table 5.
The value is set in the column of the partner station call ID of channel number "2" of 01 (652).

Next, exchange 114 searches table 401 (FIG. 4) using the channel number as a key, and finds out the IP address "13" of the IP-GW apparatus corresponding to channel number "2".
3.144.2.11 "is obtained. The exchange 114 obtains the IP address obtained here and the local station call ID “call ID-011”.
And a GW address response 605 including the call ID “Call ID-123” of the partner station as a parameter.
Send to FIG. 14 shows a GW address response 60 at this time.
5 shows the message format. GW address response 605
Is, for example, a message format 1400 as shown in FIG.
Transmits a control line transmission header, a protocol ID, a local station call ID, and a partner station ID.

SIG receiving GW address response 605
-The SV device 116 transmits the GW address response 606 including the same parameters as the GW address response 605 to the SIG-S
Transmit to the V device 106. FIG. 15 shows GW address response 6
06 form 1500. GW address response 606
Is a message format 1500 as shown in FIG.
Header, TCP header, protocol ID, own station call ID,
The partner station ID is transmitted to the SIG-SV device 106.

SIG receiving GW address response 606
-The SV device 106 sends the GW address response 607 including the same parameters as the GW address response 606 to the exchange 10
Send to 4. FIG. 16 shows a format 1600 of the GW address response 607. GW address response message 60
Reference numeral 7 denotes a message format 1600 as shown in FIG. 16, which includes a control line transmission header, a protocol ID, a local station call ID, and a partner station ID as parameters.

With the above operation, when a call is set up from the location A to the location B, it is determined which of the plurality of IP-GW devices at the location B should be connected.

The exchange 104 having received the GW address response 607 extracts the value of the call ID of the partner station from the parameters included in the GW address response 607 message. As is apparent from the operation described above, the partner station call ID is a partner station viewed from the exchange at the site B, and is a value originally generated and assigned as the own station call ID by the exchange at the site A. The exchange 104 searches the column of the local station call ID in the trunk line idle state management table 801 using the extracted value of the called station call ID (in this example, “call ID-123”) as a key. As a result of this search, the GW address response 607
Is a response to the reservation made previously for the channel number "3" (653).

On the basis of this result, the exchange 104
Is for the trunk line with the identified channel number "3".
The called number “8314502” obtained in the calling 601 and G
The IP address “133.1” obtained in the W address response 607
4.2.11 "and a call setting request 608 including the local station call ID" call ID-011 "as parameters. FIG.
7 shows the message format 17 of the call setup request 608 at that time.
00 is shown as an example. As shown in FIG. 17, the call setting request message includes parameters such as a trunk line transmission header, a protocol ID, a call number, a message type, a transmission capability, a channel identification, a calling number, a destination address, a local station call ID, and an IP address. .

The IP-GW apparatus 107 which has received the call setting request 608 whose message format is shown in FIG. 17 analyzes the parameters of the call setting request 608 and obtains the call destination IP address. And the IP-GW device 1 having the address
17, the local station call ID “call I
A call setting request 610 including "D-011" as a parameter is transmitted. Also, a call setting response 609 is transmitted to the exchange 104 (the call setting response 609 conforms to the format specified in ITU-T Q.931). An example of the format of the call setup request 610 message is shown at 1800 in FIG. IP-GW of a certain base
The call setting request from the device to the IP-GW device at another base is:
As shown in FIG. 18, parameters include an IP header, a TCP header, a protocol ID, a call number, a message type, a transmission capability, a channel identification, a calling number, a calling subaddress, a called number, a called subaddress, and a local station call ID.

The IP-GW apparatus 117 of the base B receiving the call setting request 610 similarly receives the local station call ID “call ID”.
A call setting request 612 including “-011” as a parameter is transmitted to the exchange 114, and a call setting response 611 is transmitted to the IP-GW apparatus 107 (the call setting response 611 is the ITU-T
H. 323). At this time, IP-GW
It is assumed that the call setting response 612 is performed in a mode in which the exchange 114 determines which channel is to be used in the trunk line connecting the device 117 and the exchange 114. The format of the call setup request 612 is shown in FIG. Call setup request 61
Reference numeral 2 denotes a trunk line transmission header, a protocol ID, a call number, a message type, a transmission capability, a channel identification, a calling number, a calling subaddress, a called number, a called subaddress, and a local station call, as in the message format 1900 shown in FIG. It contains parameters such as ID.

Exchange 1 receiving this call setup request 612
14 analyzes the parameters of the call setting request 612 and extracts the local station call ID “Call ID-001”. Then, using this value as a key, the trunk line idle state management table 501 is checked.
It is determined that the call setting request 612 is a request corresponding to the reservation of the channel number “2” (654). Then, a call setting response 613 including the determined channel number “2” as a parameter is transmitted to the IP-GW apparatus 117 (the call setting response 613 conforms to the format specified in ITU-T Q.931). Next, the exchange 114 obtains the called number “8314502” from the parameters of the call setting request 612, calls the telephone 112 of the own station using the number excluding the base number part as the telephone number (614), and sends the call notification 615 to the IP-IP. GW device 11
7 (call notification 615 is in accordance with ITU-T Q.931).
According to a prescribed format), a call path setting 654 for the channel number “2” is performed.

The IP-GW apparatus 117 sends a call notification 616
Is transmitted to the IP-GW apparatus 107 (the call notification 616
TU-TH. 323), and a call path setting 655 is performed. The IP-GW apparatus 107 transmits a call notification 617 to the exchange 104 (the call notification 617
U-Q. 931), and a call path setting 656 is performed.

Here, when the telephone 112 responds 618, the exchange 114, the IP-GW device 117, the IP-GW
Response notifications 619, 6 in the order of device 107 and exchange 104
20, 621 are transmitted (response notifications 619, 621 are I
TU-T Q. 620 is IT according to the format specified in 931
U-TH. 323), the telephone 10
1 and the telephone 112 are established.

With the means described above, according to the present embodiment, it is possible to select an IP-GW device having a free trunk line from a plurality of IP-GW devices of the other party at the time of call setting. Become. Further, according to the present embodiment, an effect is obtained that the call processing is completed without increasing the call processing time in proportion to the number of connected IP-GW apparatuses.

[0056]

According to the present invention, even when a plurality of IP-GW devices are provided at one site, a communication network connection control method for efficiently selecting and connecting to a connection partner IP-GW device at the time of call setup. And a communication network connection control device and a communication system using them.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the overall configuration of a system to which the present invention is applied.

FIG. 2 is a diagram showing an example of a communication network numbering plan in the embodiment.

FIG. 3 is a diagram illustrating an example of a correspondence table between a base number and an IP address of a SIG-SV device.

FIG. 4 shows a channel number of a trunk line in the embodiment;
It is a figure showing the example of the IP address correspondence table of the corresponding IP-GW.

FIG. 5 is a diagram illustrating an example of a trunk line idle state management table according to the embodiment;

FIG. 6 is a diagram illustrating a connection sequence between bases in the embodiment.

FIG. 7 shows a channel number of a trunk line in the embodiment;
FIG. 5 is a diagram illustrating an example of an IP address correspondence table of a corresponding IP-GW device.

FIG. 8 is a diagram illustrating an example of a trunk line idle state management table according to the embodiment;

FIG. 9 is a diagram illustrating a configuration of an SIG-SV according to the present embodiment.

FIG. 10 is a diagram showing a configuration of an exchange in the present embodiment.

FIG. 11 is a diagram showing an example of a format of a GW address request message.

FIG. 12 is a diagram showing an example of a format of a GW address request message.

FIG. 13 is a diagram illustrating an example of a format of a GW address request message.

FIG. 14 is a diagram showing an example of a format of a GW address response message.

FIG. 15 is a diagram showing an example of a format of a GW address response message.

FIG. 16 is a diagram illustrating an example of a format of a GW address response message.

FIG. 17 is a diagram illustrating an example of a format of a call setting request message.

FIG. 18 is a diagram illustrating an example of a format of a call setting request message.

FIG. 19 is a diagram illustrating an example of a format of a call setting request message.

[Explanation of symbols]

101, 102, 103, 111, 112, 113, 1
20, 121, 122 ... telephones, 104, 114, 12
3 exchanges, 105, 115, 124 control lines, 10
6, 116, 125 ... signaling server device, 10
7, 108, 109, 116, 117, 118, 12
6,127,128,129 ... IP gateway device,
900 bus, 901 CPU, 902 memory controller, 903 memory, 904 control line interface, 905 LAN interface, 1000 control bus, 1001 line switching bus, 1002 CPU, 10
03: memory controller, 1004: memory, 100
5: control line interface, 1006: extension interface, 1007: trunk line interface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazutoshi Tanaka 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Information and Communications Division, Hitachi, Ltd. (72) Inventor Toshihiro Ishii 216 Totsukacho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Address Co., Ltd.Hitachi, Ltd.Information and Communications Division (72) Inventor Hideyuki Toki KA05 KA13 LA14 LB02 LB08 MA04 MB16

Claims (5)

[Claims] 1. A first communication network installed at a plurality of bases is connected via a second communication network, and each of the bases transmits a call of the first communication network to a call of the second communication network. A method for controlling connection between communication networks in a communication system having a plurality of interface devices for converting a call to a first communication network to a first communication network at another site via a second communication network When connecting, select a connectable interface device from among a plurality of interface devices to be connected,
A communication network connection control method for connecting a communication network. 2. A circuit-switched network is connected via an Internet protocol network, and calls on the circuit-switched network are connected to the Internet.
A communication network connection control method for performing communication by converting a packet to a protocol packet and transmitting the packet and restoring a packet received via the Internet protocol network into a call of a circuit switching network, and performing communication. It has a plurality of gateway devices that convert circuit-switched network calls into Internet Protocol packets and transmit them, and that restore packets received via the Internet Protocol network into circuit-switched network calls. A communication network connection control method characterized by selecting a gateway device having an empty line from among a plurality of gateway devices of the circuit switching network and performing connection control. 3. A first communication network installed at a plurality of bases is connected via a second communication network, and each of the bases transmits a call of the first communication network to a call of the second communication network. A connection control device between communication networks in a communication system having a plurality of interface devices for converting a call to a first communication network to a first communication network at another site via a second communication network A communication network connection control device, wherein a connectable interface device is selected from the plurality of interface devices at each of the bases, and control is performed to connect a communication network. 4. An exchange accommodating a plurality of terminals, a circuit switch network connected to the exchange, which converts a call of a circuit switching network into an Internet Protocol packet, and converts a packet received via the Internet protocol network into a call of the circuit switching network. A circuit switching network having a plurality of gateway devices for restoring a communication network is a communication network connection control device in a communication system connected via an Internet protocol network, wherein the communication network connection control device cooperates with the call processing of the exchange to set a connection destination at the time of call setting. A communication network connection control device for performing connection control by selecting a gateway device having a vacant line with a connection destination exchange from a plurality of gateway devices. 5. The circuit switching network of a plurality of bases is connected to the Internet
A communication system connected via a protocol network, wherein each of the circuit switching networks includes an exchange accommodating a plurality of terminals,
Calls on the circuit switching network connected to the exchange
A plurality of gateway devices for converting the packets received through the Internet protocol network into packets of a protocol and restoring the packets into calls of the circuit switching network; A communication system, comprising: a control device that selects a gateway device having an empty line with a connection destination exchange from among the devices and controls connection.