JP2011244083A - Gateway device and communication control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain gateway devices by which low delay transmission of voice data is attained and SIP message exchange by End-To-End is attained.SOLUTION: The present invention provides gateway devices 11 and 12 which constitute a communication system with the opposite devices with the same configurations as those of themselves, have functions as SIP proxy servers, and by which communication via a packet service network 3 and communication via a voice service network 4 with the opposite devices are possible, when an INVITE message is received from VoIP terminals 511 and 521 which make themselves as the SIP proxy servers, establish a first communication path via the packet service network 3 and a second communication path via the voice service network 4 with the opposite devices which operate as SIP proxy servers of a destination terminal of the INVITE message, perform transmission of the SIP message using the first communication path, and perform transmission of the voice data using the second communication path.

Description

  The present invention relates to a gateway apparatus and a communication control method for connecting an IP network to another network.

  In various communication networks, a method of integrating voice communication such as telephone and data communication on an IP (Internet Protocol) network has become widespread. A technique for transmitting voice communication over an IP network is called VoIP (Voice over IP). Non-Patent Document 1 standardizes SIP (Session Initiation Protocol) as one of the call control protocols in the VoIP system. As a merit of SIP, easiness of expansion can be given by adopting a text-based message format like HTTP (Hyper Text Transfer Protocol) used in WEB. For example, in addition to the conventional telephone function, it is possible to use extended functions such as multipoint conference, presence, and short message.

  In the VoIP system, a device that relays between the telephone network and the IP network is called a VoIP gateway. The VoIP gateway converts analog voice data input from a telephone line into digital data, divides it into IP packets, and transmits them to the IP network. Also, the IP packet received from the IP network side is restored to analog voice and sent to the telephone network. The VoIP gateway also compresses and decompresses digital audio data.

  On the other hand, in a radio access line such as a mobile communication system, a voice service and a packet service may be distinguished. In such packet services, pay-per-use or conditional flat-rate systems are common, and delivery confirmation and order control are implemented in the data link layer in the wireless section in order for the carrier to accurately measure user traffic. Is done. For this reason, even when packet communication is performed using an unreliable host protocol such as User Datagram Protocol (UDP), the packet is transmitted reliably in the wireless section by the function of the data link layer. Is done.

Internet Engineering Task Force (IETF), RFC 3261

  Between VoIP terminals connected using a voice service via a VoIP gateway, SIP messages are converted into telephone network control messages at the VoIP gateway, so that SIP messages can be exchanged end-to-end. There is a problem that the extension function cannot be obtained.

  On the other hand, between VoIP terminals connected using a packet service for which delivery confirmation and order control in the wireless section as described above are performed, packet retransmission and reconfiguration are performed by delivery confirmation and order control, and delay is reduced. appear. When a wireless section is included in the communication path between such VoIP terminals, in performing VoIP communication, the real-time property of communication is impaired due to the delay as described above, and sufficient voice quality cannot be obtained. There is.

  The present invention has been made in view of the above, and realizes low-delay transmission of voice data in a communication system in which VoIP communication is performed using a line in which voice service and packet service are distinguished. It is an object of the present invention to obtain a gateway device and a communication control method that realize end-to-end SIP message exchange.

  In order to solve the above-described problems and achieve the object, the present invention configures a communication system together with a counter device having the same configuration as itself, has a function as a SIP proxy server, and performs packet service with the counter device. A gateway device capable of communication via a network and communication via a voice service network, and when receiving an INVITE message from a terminal that is itself a SIP proxy server, operates as a SIP proxy server of the destination terminal of the INVITE message A first communication path via the packet service network and a second communication path via the voice service network are established with the opposite device, and the SIP message is transmitted via the first communication path. Audio data is transmitted using the second communication path. To.

  According to the present invention, between gateway devices, voice data is transmitted / received on a voice service line and SIP data is transmitted / received on a packet service line, so that deterioration of voice quality is prevented and SIP End-To-End is achieved. It is possible to realize a communication system in which reachability is ensured.

FIG. 1 is a diagram illustrating an example of a communication system configured to include the gateway device according to the first embodiment. FIG. 2 is a diagram illustrating a configuration example of the gateway device. FIG. 3 is a diagram illustrating an example of an ID correspondence table. FIG. 4 is a diagram showing an example of a SIP message (INVITE message) that means transmission of a VoIP terminal. FIG. 5 is a diagram illustrating an example of an INVITE message that the gateway device according to the second embodiment transmits to a facing gateway device. FIG. 6 is a diagram illustrating an example of a 100 Trying message transmitted by the gateway device according to the third embodiment. FIG. 7 is a diagram illustrating an example of a 100 Trying message transmitted by the gateway device according to the fourth embodiment.

  Embodiments of a gateway device and a communication control method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating an example of a communication system configured to include the gateway device according to the present embodiment.

  The communication system according to the present embodiment includes communication terminals 21 and 22 that can perform communication via the packet service network 3 and communication via the voice service network 4, and a gateway device 11 that connects the communication terminal 21 and the LAN 51. The gateway device 12 that connects the communication terminal 12 and the LAN 52, the plurality of VoIP terminals 511 connected to the LAN 51, and the plurality of VoIP terminals 521 connected to the LAN 52 are included.

  In the communication system configured as described above, the communication terminals 21 and 22 are devices for using the packet service and voice service provided by the communication carrier, and more specifically, wireless terminals such as mobile phone terminals and satellite phone terminals. A terminal or a wired terminal such as an ADSL modem. The packet service network 3 is a network that can be accessed by a packet service provided by a communication carrier. On the other hand, the voice service network 4 is a network that can be accessed by a voice service provided by a telecommunications carrier. The packet service network 3 and the voice service network 4 may be a plurality of interconnected service networks. Therefore, the communication terminals 21 and 22 may be connected to different service networks as long as they are connected to each other, and need not be devices for using services provided by the same communication carrier. For convenience of explanation, FIG. 1 shows two gateway devices, but three or more gateway devices may be used.

  The gateway devices 11 and 12 are gateway devices according to the present invention and have a function as a SIP proxy server. Further, the communication terminal 21 can be controlled via the interface 111. This control includes start / end of the packet service, packet transmission / reception using the packet service, start / end of the voice service, and voice transmission / reception using the voice service. There may be a plurality of interfaces 111 between the gateway device 11 and the communication terminal 21. Different interfaces may be used for the packet service and the voice service. The interface 112 between the gateway device 12 and the communication terminal 22 is the same.

  The gateway device 11 is connected to a plurality of VoIP terminals 511 via the LAN 51. The VoIP terminal 511 uses the gateway device 11 as a SIP proxy server, and transmits a SIP message to the gateway device 11. Similarly, the gateway device 12 is connected to a plurality of VoIP terminals 521 via the LAN 52, and the VoIP terminal 511 uses the gateway device 11 as a SIP proxy server.

  The internal configuration of the gateway devices 11 and 12 will be described. These gateway apparatuses 11 and 12 have the same internal configuration. Therefore, the configuration of the gateway device 11 will be described here. FIG. 2 is a diagram illustrating a configuration example of the gateway device 11.

  As illustrated, the gateway device 11 includes a SIP processing unit 101, a voice conversion unit 102, a communication terminal control unit 103, a storage unit 104, a NAT processing unit 105, and a LAN communication unit 106, which are held in the storage unit 104. The information includes an ID correspondence table.

  The SIP processing unit 101 performs SIP communication via a LAN line (communication path between the LAN 51) and a packet service line (communication path for packet transmission connected to the packet service network 3 via the communication terminal 21). To do. More specifically, SIP message transmission / reception, in particular, processing for adding and changing SIP message information between a LAN line and a packet service line and relaying is performed. The addition and change of information in the relay of the SIP message is aimed at associating the voice line with the SIP session.

  The voice conversion unit 102 transmits voice data to be transmitted / received via a LAN line and voice data to be transmitted / received via a voice service line (a voice data transmission communication path connected to the voice service network 4 via the communication terminal 21). Convert. That is, the received audio data is converted into audio data in a format according to the method applied to the transfer destination communication path.

  The communication terminal control unit 103 controls the communication terminal 21 to establish a packet service line and a voice service line with the opposite device (the communication terminal connected to the opposite gateway device).

  The ID correspondence table held in the storage unit 104 is a table in which the correspondence between the identifier of each VoIP terminal 511 connected via the LAN 51 and the connection destination of the voice service line is recorded.

  The NAT processing unit 105 performs address conversion between an IP packet transmitted / received via a LAN line and an IP packet transmitted / received via a packet service line. Since NAT (Network Address Translation), which is a process performed by the NAT processing unit 105, is a well-known technique in the technical field of the present invention, detailed description thereof is omitted. Since an IP address is included in the SIP message, there is a technical problem with respect to the transmission / reception of the SIP message via the NAT (transmission / reception of the SIP message when the NAT is configured in the middle), Also in the present invention, it is necessary to solve this technical problem. For this technical problem, SIP such as Universal Plug and Play (UPnP), Simple Traversal of UDP through NATs (STUN), etc., a method for detecting the presence of NAT on the terminal side, and Back to Back User Agent (B2BUA), etc. A method for performing address translation at the SIP layer on the server side is well known, and the dateway device 11 of the present embodiment can take these NAT traversal methods without limitation (existing how May be used).

  The LAN communication unit 106 controls communication via a LAN line, and provides a transmission / reception function of IP or Ethernet (registered trademark). Since this function is also well known in the technical field of the present invention, description thereof is omitted.

  Note that the gateway device 11 may have the function of the communication terminal 21. In this case, for example, the communication terminal control unit 103 performs processing (control for using packet service and voice service) performed in the communication terminal 21.

  Next, the operation of the communication system according to the present embodiment will be described. In the present embodiment, it is assumed that the gateway device 11 holds the ID correspondence table illustrated in FIG. 3, and the VoIP terminal 511 connected to the gateway device 11 via the LAN 51 is connected to the gateway device via the LAN 52. The operation when making a call to the VoIP terminal 521 connected to the terminal 12 will be described. Here, the operation of the gateway apparatuses 11 and 12 that execute characteristic processing will be mainly described.

  The ID correspondence table is a fixed table. In the ID correspondence table shown in FIG. 3, the domain name indicates the domain name of the SIP URI used as an identifier in VoIP communication. An identifier in VoIP communication such as an IP address or SIP URI can be used instead of the domain name. The telephone number is a telephone number held by the SIP server in the domain indicated by the domain name. The opposite gateway is identification information of an opposite device (communication partner gateway device) when the gateway device 11 communicates via the packet service network 3, and is an IP address.

  When the gateway device 11 receives a SIP message indicating transmission of the VoIP terminal from the VoIP terminal 511, the gateway device 11 acquires the SIP URI of the transmission destination from the received SIP message. Then, the held ID correspondence table is confirmed. For example, when the destination is a URI existing in example.com, the SIP standard is defined for the opposite gateway associated with this example.com. Then, the SIP message is transferred. At this time, the telephone number associated with the acquired SIP URI is derived using the ID correspondence table, and the telephone number is connected via the voice service network 4. FIG. 4 is a diagram illustrating an example of an INVITE message that is a SIP message meaning transmission of a VoIP terminal. The part surrounded by the broken line in FIG. 4 is the SIP URI of the destination.

  The gateway device 12 operating as the SIP proxy server of the VoIP terminal 521 that is a communication partner of the VoIP terminal 511 receives the SIP message (INVITE message) addressed to the VoIP terminal 521 via the packet service line and also uses the voice service line. Receive incoming calls via. The gateway device 12 transfers the received SIP message to the VoIP terminal 521. After that, when a session (voice session by SIP) between the VoIP terminal 521 and the VoIP terminal 511 is established by SIP, the gateway device is triggered by this. 11 establishes a voice service line.

  When the voice service line is established, the gateway apparatuses 11 and 12 mutually convert the voice data on the LAN line and the voice data on the voice service line by the voice conversion operation by both voice conversion units 102 and transmit them.

  As described above, in the communication system according to the present embodiment, the gateway device operating as the SIP proxy server holds the telephone number information of the opposing SIP proxy server in advance, and from the VoIP terminal via the LAN to which the gateway device is connected. When a SIP message (INVITE message) meaning outgoing is received, a voice session by SIP is established via the packet service network, and the telephone number associated with the SIP URI included in the received message is sent via the voice service network. A call is made to establish a voice service line with the opposite gateway device. The SIP message transmission between the gateway devices is performed via the packet service network, and the voice data transmission is performed via the voice service network. Thereby, the VoIP terminal connected via the gateway device can transmit and receive voice data on the voice service line and can transmit and receive SIP data on the packet service line. As a result, it is possible to prevent the deterioration of voice quality and secure the reachability of SIP End-To-End, thereby realizing the expandability.

Embodiment 2. FIG.
Next, the gateway device according to the second embodiment will be described. In the present embodiment, a gateway device that obtains the same effect as in the first embodiment by a method different from the method described in the first embodiment will be described. The configuration of the communication system including the gateway device of the present embodiment and the configuration of the gateway device are the same as those of the first embodiment (see FIGS. 1 and 2). In this embodiment, the description of the parts common to the first embodiment is omitted.

  As with the gateway device of the first embodiment, the gateway device of the present embodiment establishes a session via the packet service network 3 when receiving an INVITE message (SIP message meaning outgoing) from the VoIP terminal. No transmission is made to the gateway device via the voice service network 4. Instead, a part of the INVITE message received from the VoIP terminal is modified and transferred to the packet service network 3.

  For example, when the INVITE message transmitted from the VoIP terminal is the one shown in FIG. 4, the gateway apparatus of the present embodiment that has received this message modifies a part of the message and changes the INVITE message shown in FIG. Generate and transmit to the opposite gateway device. FIG. 5 is a diagram illustrating an example of an INVITE message that the gateway device according to the second embodiment transmits to a facing gateway device.

  As shown in FIG. 4 and FIG. 5, when the gateway apparatus according to the present embodiment receives an INVITE message from a VoIP terminal, it assigns an identifier (that is, a telephone number) in its own voice service network, and is opposed to the gateway apparatus. Forward towards. In FIG. 5, “GW-Phone-Number: 9765432” is information added by the gateway device.

  Further, when the gateway apparatus according to the present embodiment receives an INVITE message to which identifier information (GW-Phone-Number: xxxx) in the voice service network of the opposite gateway apparatus is added, the added information ( (GW-Phone-Number: xxxx) is deleted and the INVITE message is transferred to the VoIP terminal to establish a session between the VoIP terminals. In addition, before deleting the added information, the content is confirmed, the identifier in the voice service network of the opposite gateway device is acquired, and the above-mentioned acquired with the establishment of the voice session by SIP as an opportunity Make a call to the identifier. As a result, a voice service line is established with the opposite gateway apparatus, and a voice session by SIP via the packet service network 3 and a voice service line via the voice service network 4 are established as in the first embodiment. To do.

  As described above, in the communication system according to the present embodiment, when the gateway device operating as the SIP proxy server receives the INVITE message from the VoIP terminal via the LAN to which the gateway device is connected, the gateway device uses its identifier in the voice service network as the INVITE. When an INVITE message to which an identifier in the voice service network is added is received after being added to the message, a voice session is established via the packet service network 3 and the added identifier is To establish a voice service line via the voice service network 4. The SIP message transmission between the gateway devices is performed via the packet service network, and the voice data transmission is performed via the voice service network. Thus, as in the first embodiment, a VoIP terminal connected via the gateway device can transmit and receive voice data on the voice service line and can transmit and receive SIP data on the packet service line. As a result, it is possible to prevent the deterioration of voice quality and secure the reachability of SIP End-To-End, thereby realizing the expandability.

  Further, the gateway device does not need to hold an ID correspondence table (see FIG. 3). When the gateway apparatus has a plurality of voice service lines, an identifier indicating an unused voice service line is added to the INVITE message and transmitted, whereby the voice line can be used efficiently. .

Embodiment 3 FIG.
Next, the gateway device according to the third embodiment will be described. In the present embodiment, a modified example of the gateway device of the second embodiment will be described. The configuration of the communication system including the gateway device of the present embodiment and the configuration of the gateway device are the same as those of the first embodiment (see FIGS. 1 and 2). In the present embodiment, the description of the parts common to the second embodiment is omitted.

  The gateway device according to the present embodiment makes it unnecessary to maintain the ID management table (see FIG. 3) required in the first embodiment by the same procedure as the gateway device according to the second embodiment. When a response message (100 Trying message) to the INVITE message transmitted from the opposing gateway device is received from the VoIP terminal and transferred, as shown in FIG. Forward the message after adding the phone number. FIG. 6 is a diagram illustrating an example of a 100 Trying message transmitted by the gateway device according to the third embodiment, and “GW-Phone-Number: 12345678” is information added by the gateway device. The gateway device that has received this response message (the gateway device on the INVITE message transmission side) can know the telephone number of the opposite gateway device.

  Although the case has been described where the identifier in the voice service network is added to the response message for the INVITE message and notified, the gateway device that has received the INVITE message may be a SIP message that is subsequently transmitted, even if it is other than 100 Trying messages. Yes (may be added to other messages and notified).

  As described above, in the communication system according to the present embodiment, the gateway device that operates as the SIP proxy server transfers the identifier after adding the identifier in its voice service network to the INVITE message, similarly to the gateway device according to the second embodiment. When an INVITE message to which an identifier in the voice service network is added is received, a voice session is established via the packet service network 3 and a call is made to the added identifier to The voice service line is established via the network 4. Furthermore, an identifier in its own voice service network is notified to the originating gateway device using a response message to the INVITE message or other SIP message. Thereby, the same effect as Embodiment 2 can be acquired.

  In addition, when a voice service line is established, the gateway device that has transmitted the INVITE message uses a caller ID notification function that can be used with a general voice service line to receive a voice call (voice service network) from the opposite gateway device. 4). For example, according to the procedure according to this embodiment, the gateway device on the side that transmitted the INVITE message differs from other callers (the opposite gateway device) at the timing when the voice service line is established with the opposite gateway device. Even when there is an incoming call from the (device), it can be recognized that it is an incoming call from another caller, and the effect that no error occurs in the correspondence between the SIP session and the voice service line can be obtained.

  In the embodiment, since both gateway apparatuses that perform communication acquire the identifiers indicating the voice service lines of each other, both of them can start outgoing calls on the voice service lines.

Embodiment 4 FIG.
Next, the gateway device according to the fourth embodiment will be described. In the present embodiment, a modification of the gateway device according to the second and third embodiments will be described. The configuration of the communication system including the gateway device of the present embodiment and the configuration of the gateway device are the same as those of the first embodiment (see FIGS. 1 and 2). In the present embodiment, the description of the parts common to the second and third embodiments is omitted.

  The gateway device according to the present embodiment is configured such that the gateway device according to the second or third embodiment uses a DTMF (Dual-Tone Multi-Frequency) function of a voice service network.

  Specifically, the same operation as that of the gateway device of the second embodiment or the gateway device of the third embodiment is performed, and a response message (100 Trying message) of the INVITE message transmitted from the opposite gateway device is sent to the VoIP terminal. When the voice service line is received, information indicating a DTMF signal to be transmitted when a voice service line is established as shown in FIG. FIG. 7 is a diagram illustrating an example of a 100 Trying message transmitted by the gateway device according to the fourth embodiment, and “GW-DTMF-Code: 2468” is information added by the gateway device.

  When the gateway device adds the information of the DTMF signal to the 100 Trying message and transmits the message, the gateway device receives the DTMF signal after the voice service line is established (the gateway device to which the 100 Trying message is transmitted). Send. As a result, it can be seen that the opposite gateway apparatus is a voice incoming call from the gateway apparatus that has transmitted the 100 Trying message.

  As described above, in the communication system according to the present embodiment, the gateway device operating as the SIP proxy server adds the identifier of its own voice service network to the INVITE message, similarly to the gateway device according to the second or third embodiment. When an INVITE message with an identifier added in the voice service network is received, a voice session is established via the packet service network 3 and a call is made to the added identifier. The voice service line is established via the voice service network 4. Further, DTMF signal information is added to the response message for the INVITE message and then transmitted. After the voice service line is established, a DTMF signal corresponding to the DTMF signal information added to the response message is transmitted. . As a result, the same effects as in the second embodiment can be obtained, and, similarly to the third embodiment, the gateway device that has transmitted the INVITE message can receive a voice call from the opposite gateway device (via the voice service network 4). Can be confirmed.

  Note that the information of the DTMF signal may be transmitted using another message transmitted after this instead of the 100 Trying message.

  As described above, the gateway device according to the present invention is useful for a gateway device that operates as a SIP proxy server, and in particular, a communication system that performs VoIP communication using a line in which a voice service and a packet service are distinguished. Suitable for configuring gateway devices.

3 Packet service network 4 Voice service network 11, 12 Gateway device 21, 22 Communication terminal 51, 52 LAN
DESCRIPTION OF SYMBOLS 101 SIP processing part 102 Voice conversion part 103 Communication terminal control part 104 Storage part 105 NAT processing part 106 LAN communication part 111,112 Interface 511,521 VoIP terminal

Claims (11)

A gateway device that constitutes a communication system with a counter device having the same configuration as itself, has a function as a SIP proxy server, and can communicate with the counter device via a packet service network and a voice service network Because
When an INVITE message is received from a terminal that uses itself as a SIP proxy server, a first communication path via the packet service network is established with the opposite device operating as the SIP proxy server of the destination terminal of the INVITE message. And a second communication path through the voice service network is established, the SIP message is transmitted using the first communication path, and the voice data is transmitted using the second communication path. A gateway device characterized by Communication control for performing control for establishing a voice session by SIP as the first communication path via the packet service network and control for establishing a voice service line as the second communication path via the voice service network Means,
SIP processing means for relaying SIP messages;
The gateway device according to claim 1, comprising: Correspondence between identification information in the packet service network of the opposite device operating as a SIP proxy server of a terminal capable of VoIP communication with a terminal that is itself a SIP proxy server, and identification information in the voice service network of the opposite device Storage means for storing an ID correspondence table indicating the relationship;
Further comprising
The gateway device according to claim 2, wherein the communication control unit establishes the voice service line based on the ID correspondence table. The SIP processing unit, when transferring an INVITE message received from a terminal that is used as a SIP proxy server to the opposite device, adds the identification information in the voice service network of the own device to the INVITE message, and transmits the message.
The communication control means establishes the voice service line with the opposite device based on identification information in the voice service network of the opposite device notified from the opposite device using an INVITE message. The gateway device according to claim 2. The SIP processing unit further transmits the response message with respect to the INVITE message received from the opposite device, or a message transmitted after the response message with identification information in the voice service network of the own device. The gateway device according to claim 4. The SIP processing unit further transmits a response message to the INVITE message received from the opposite device, or a message to be transmitted after the response message with information on a predetermined DTMF signal added thereto,
5. The communication control means, after establishing the voice service line with the opposite device, transmits a DTMF signal corresponding to the information of the predetermined DTMF signal to the opposite device. Or the gateway apparatus of 5. A plurality of gateway devices having functions as SIP proxy servers are included, and each gateway device is configured to be able to communicate with other gateway devices via a packet service network and via a voice service network. A communication control method executed in a communication system,
Of the plurality of gateway devices, the first gateway device that has received the INVITE message from the terminal that is the SIP proxy server itself, to the second gateway device that is operating as the SIP proxy server of the destination terminal of the INVITE message A first communication path establishing step of transferring the INVITE message to perform voice session establishment control by SIP and establishing a first communication path with the second gateway device;
A second communication path establishing step in which the first gateway apparatus and the second gateway apparatus establish a second communication path via the voice service network;
Including
Each gateway device connected by the first and second communication paths performs transmission of SIP messages using the first communication path, and also transmits voice data using the second communication path. The communication control method characterized by performing as follows. The plurality of gateway devices respectively hold ID correspondence tables indicating correspondence relationships between identification information in the packet service network and identification information in the voice service network of gateway devices other than itself,
The communication control method according to claim 7, wherein, in the second communication path establishment step, the second communication path is established based on the held ID correspondence table. In the first communication path establishment step,
The first gateway device adds the identification information in the voice service network of its own device to the INVITE message and transfers it,
In the second communication path establishment step,
The said 2nd gateway apparatus performs establishment control of a said 2nd communication path based on the said identification information added to the INVITE message received from the said 1st gateway apparatus. Communication control method. In the first communication path establishment step,
The second gateway device transmits the response message to the INVITE message received from the first gateway device or identification information in the voice service network of the own device added to the message transmitted after the response message. The communication control method according to claim 9. In the first communication path establishment step,
The second gateway apparatus transmits a response message to the INVITE message received from the first gateway apparatus or a message transmitted after the response message with information on a predetermined DTMF signal added thereto,
The second gateway apparatus further transmits a DTMF signal corresponding to information of the predetermined DTMF signal to the first gateway apparatus after the second communication path is established. The communication control method according to 9 or 10.

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