JP7566254B2 - Gateway device and communication system - Google Patents

Description

This disclosure relates to communication technology, and in particular to gateway devices and communication systems.

Currently, the use of PBX (Private Branch eXchange) (hereinafter also referred to as "Cloud PBX"), which is installed on the cloud (e.g., a data center different from the user's base) and provides internal line switching functions and external line connection functions via the Internet to telephones installed at the user's base, is expanding (see, for example, Patent Document 1). A communication system using Cloud PBX has the advantage of low initial implementation costs, since internal calls can be used by paying a service fee without purchasing expensive switching equipment.

JP 2015-103837 A

Users of Cloud PBX may wish to continue using the telephone number of their base (also called the "area number"). In the past, in order to achieve this, it was necessary to install an expensive VoIP gateway device at the user's base, which performs protocol conversion to connect the communications carrier and the Cloud PBX, and this could result in significant costs.

This disclosure has been made in light of the above-mentioned problems, and one of its objectives is to provide technology that supports both the continued use of a user's base telephone number and the inexpensive use of a cloud PBX.

In order to solve the above problem, a gateway device according to one aspect of the present disclosure is a gateway device provided at a location different from the user's base, and includes: an acquisition unit that acquires an IP address of a communication device provided by a communication carrier to a communication device connected to the communication carrier's network at the user's base, and an IP address of a Session Initiation Protocol (SIP) server of the communication carrier; a registration unit that passes a registration message including the IP address of the communication device and addressed to the IP address of the SIP server to the communication device, and transmits the registration message from the communication device to the communication carrier's network; a reception unit that receives a SIP message that has been transmitted from the SIP server to the communication device and forwarded from the communication device; and a forwarding unit that forwards the SIP message forwarded from the communication device to an exchange provided at a location different from the user's base and that controls a telephone terminal provided at the user's base.

Another aspect of the present disclosure is also a gateway device. This device is a gateway device provided at a location different from the user's base, and includes: a storage unit that stores information provided by a communications carrier, the information including an IP address of a communications device provided at the user's base and connected to the communications carrier's network, and an IP address of a SIP server of the communications carrier; a registration unit that passes a registration message including the IP address of the communications device and addressed to the IP address of the SIP server to the communications device, and transmits the registration message from the communications device to the communications carrier's network; a reception unit that receives a SIP message transmitted from the SIP server to the communications device and forwarded from the communications device; and a forwarding unit that forwards the SIP message forwarded from the communications device to an exchange provided at a location different from the user's base that controls a telephone terminal provided at the user's base.

Yet another aspect of the present disclosure is a communication system. This communication system includes a communication device provided at a user's base and connected to a communication carrier's network, an exchange provided at a location different from the user's base, and a gateway device provided at a location different from the user's base. The gateway device acquires the IP address of the communication device provided by the communication carrier to the communication device and the IP address of the communication carrier's SIP server, the gateway device passes a registration message including the IP address of the communication device and addressed to the IP address of the SIP server to the communication device, the communication device transmits the registration message to the communication carrier's network, the communication device forwards the SIP message to the gateway device when it receives the SIP message from the SIP server, the gateway device forwards the SIP message forwarded from the communication device to the exchange, and the exchange controls a telephone terminal provided at the user's base based on the SIP message forwarded from the gateway device.

Yet another aspect of the present disclosure is also a communication system. This communication system includes a communication device provided at a user's base and connected to a communication carrier's network, an exchange provided at a location different from the user's base, and a gateway device provided at a location different from the user's base. The gateway device stores information provided by the communication carrier, including an IP address of the communication device and an IP address of a SIP server of the communication carrier, the gateway device passes a registration message including the IP address of the communication device and addressed to the IP address of the SIP server to the communication device, the communication device transmits the registration message to the communication carrier's network, the communication device forwards the SIP message to the gateway device when it receives the SIP message from the SIP server, the gateway device forwards the SIP message forwarded from the communication device to the exchange, and the exchange controls a telephone terminal provided at the user's base based on the SIP message forwarded from the gateway device.

In addition, any combination of the above components, or any conversion between the expressions of this disclosure as a method, a computer program, or a recording medium storing a computer program, is also valid as an aspect of this disclosure.

This disclosure can help users continue to use their base telephone numbers while also providing low-cost use of cloud PBX.

FIG. 1 is a diagram illustrating a configuration of a conventional communication system. FIG. 1 is a sequence diagram showing an operation of a conventional communication system. FIG. 3 is a sequence diagram showing the operation of the communication system subsequent to FIG. 2 . FIG. 1 is a diagram illustrating a configuration of a communication system according to an embodiment. FIG. 5 is a block diagram showing functional blocks of the gateway device of FIG. 4. FIG. 13 is a diagram illustrating an example of a SIP message after SIP-NAT. FIG. 2 is a sequence diagram showing an operation of the communication system according to the embodiment. FIG. 8 is a sequence diagram showing the operation of the communication system following FIG. 7 . FIG. 1 illustrates an example of communication via a VPN tunnel.

Before explaining the communication system of the embodiment, the prior art will be explained. Fig. 1 shows the configuration of a conventional communication system 10. Fig. 1 shows a conventional configuration for using a cloud PBX (PBX 52) while continuing to use the telephone number of the user's base. The carrier network 14 is a network of a communication carrier (in other words, a telecommunications carrier) that provides IP telephone services, and is a next generation telephone network (Next Generation Network) that uses Internet Protocol technology. The carrier network 14 is connected to the Internet 12 via an ISP (Internet Service Provider) 20.

The carrier network 14 includes a SIP server 30 that controls signaling in IP telephone services, a DHCP (Dynamic Host Configuration Protocol) server 32, and a relay device 38. The carrier network 14 is also connected to a telephone terminal 36 that communicates with a telephone terminal at a user's location (telephone terminal 46, described below).

The access line 16 is a line that connects the Internet 12 with the user's location. The access line 16 is connected to the Internet 12 via the ISP 22. In addition, the access line 16 is provided with a relay device 50 that is connected to the device at the user's location.

The service provider network 18 is a network of a service provider that provides a cloud PBX service, and is, for example, a network built in the service provider's data center. The service provider network 18 is connected to the Internet 12 via an L3 (layer 3) switch 24. The service provider network 18 is provided with a PBX 52 as a cloud PBX. The PBX 52 is a private branch exchange that controls telephone terminals (telephone terminals 46 described below) at the user's site. For example, the PBX 52 controls internal calls between multiple telephone terminals at the user's site and external line (public line) connections.

The user site is the site of a user who uses the cloud PBX service, for example, the head office, branch office, or call center of a user company. The user site is provided with an ONU device 40, an IP telephone adapter 42, a VoIP gateway 44, multiple telephone terminals 46 (for example, telephone terminal 46a, telephone terminal 46b), and an L2 (layer 2) switch 48.

The ONU device 40 is an optical line termination device that converts between optical and electrical signals. The IP telephone adapter 42 converts between SIP messages, which are signaling packets in IP telephones, RTP (Real-time Transport Protocol) packets, which are voice packets, and ISDN (Integrated Services Digital Network) signals for general business phones. The IP telephone adapter 42 may be loaned to IP telephone service users by a communications carrier.

Each of the multiple telephone terminals 46 may be an IP telephone or a softphone compatible with IP telephones (such as a PC with a softphone installed). The L2 switch 48 relays data sent and received between the user base and the access line 16.

The VoIP gateway 44 converts between IP telephone SIP messages and RTP packets and ISDN signals. The VoIP gateway 44 sends a SIP message corresponding to the ISDN signal output from the IP telephone adapter 42 to the PBX 52, and also outputs an ISDN signal corresponding to the SIP message sent from the PBX 52 to the IP telephone adapter 42.

Figure 2 is a sequence diagram showing the operation of a conventional communication system 10. When the telephone terminal 36 is started, it executes a process of registering with the SIP server 30. When the telephone terminal 46 is started, it executes a process of registering with the PBX 52. When the IP telephone adapter 42 at the user site is started, it sends a DHCP request to the DHCP server 32. The DHCP server 32 assigns a global IP address to the IP telephone adapter 42 and sends a DHCP response to the IP telephone adapter 42.

The DHCP response includes (1) the global IP address assigned to the IP telephone adapter 42, (2) network information (subnet mask, default gateway information, etc.), (3) SIP server 30 information (global IP address of the SIP server 30, etc.), and (4) the telephone number of the IP telephone adapter 42 that is predetermined by the communications carrier (specifically, a list of one or more telephone numbers assigned to the user's location). Hereinafter, the information (1) to (4) is collectively referred to as "carrier setting information."

The DHCP server 32 also notifies the SIP server 30 of the global IP address assigned to the IP telephone adapter 42. The SIP server 30 stores the line information (line ID, etc.) of the user's base, which is predetermined by the communications carrier, in association with the global IP address of the IP telephone adapter 42. The IP telephone adapter 42 sends a SIP message including a registration request to the SIP server 30. The SIP server 30 determines that the sender is a legitimate sender based on the global IP address of the IP telephone adapter 42 included in the SIP message and the line information from which the SIP message was sent, and executes the registration process for the SIP client. The SIP server 30 sends a SIP message indicating successful registration (200 OK (REGISTER)) to the IP telephone adapter 42.

Below, we will explain an example of making a call from a telephone terminal 36 located outside the user site to a telephone terminal 46 located within the user site. The telephone terminal 36 sends a SIP message (hereinafter also referred to as an "INVITE message") including an INVITE request specifying the telephone number of the user site to the SIP server 30. The SIP server 30 sends the INVITE message to the IP telephone adapter 42 at the user site according to the specified telephone number.

The IP telephone adapter 42 sends an ISDN signal "SETUP" corresponding to the INVITE message to the VoIP gateway 44. The VoIP gateway 44 sends an INVITE message corresponding to the ISDN signal "SETUP" to the PBX 52. This INVITE message passes through the L2 switch 48, the access line 16, the Internet 12, and the L3 switch 24 and arrives at the PBX 52 of the service provider network 18.

The PBX 52 sends an INVITE message to the telephone terminal 46 that corresponds to the specified telephone number. Since this is well known, detailed explanation will be omitted, but a SIP message indicating processing (100 trying) and a SIP message indicating calling (180 Ringing) are sent in sequence from the IP telephone adapter 42 at the user's base to the SIP server 30.

Figure 3 is a sequence diagram showing the operation of the communication system 10 following Figure 2. Explanation of the PRACK request and response is omitted. When the person in charge at the user site answers the phone, the telephone terminal 46 sends a SIP message indicating that there is a response (200 OK w/SDP (INVITE)) (hereinafter also referred to as a "response message") to the PBX 52. The PBX 52 sends the response message to the VoIP gateway 44. The VoIP gateway 44 sends an ISDN signal "CONNECT" corresponding to the response message to the IP telephone adapter 42. The VoIP gateway 44 also sends a SIP message indicating an ACK request (hereinafter also referred to as an "ACK message") to the PBX 52. The PBX 52 sends the ACK message to the telephone terminal 46.

The IP telephone adapter 42 sends a response message corresponding to the ISDN signal "CONNECT" to the SIP server 30. The SIP server 30 sends the response message to the telephone terminal 36. The telephone terminal 36 sends an ACK message to the SIP server 30. The SIP server 30 sends the ACK message to the IP telephone adapter 42. The IP telephone adapter 42 sends an ISDN signal "CONNECT-ACK" corresponding to the ACK message to the VoIP gateway 44. Through the above signaling process, a voice call session is established (1) between the telephone terminal 36 and the IP telephone adapter 42, (2) between the IP telephone adapter 42 and the VoIP gateway 44, and (3) between the VoIP gateway 44 and the telephone terminal 46.

When voice is input to the telephone terminal 46, the telephone terminal 46 transmits an RTP packet containing the voice data to the VoIP gateway 44. The VoIP gateway 44 transmits the voice data to the IP telephone adapter 42 via the ISDN B channel. The IP telephone adapter 42 transmits the RTP packet containing the voice data received via the ISDN B channel to the telephone terminal 36.

On the other hand, when voice is input to the telephone terminal 36, the telephone terminal 36 transmits an RTP packet including the voice data to the IP telephone adapter 42. The IP telephone adapter 42 transmits the voice data to the VoIP gateway 44 via the ISDN B channel. The VoIP gateway 44 transmits the RTP packet including the voice data received via the ISDN B channel to the telephone terminal 46.

Thus, in the past, in order to use a cloud PBX while continuing to use the telephone number of the user's base, it was necessary to install an expensive VoIP gateway on-premise at the user's base, which could result in significant costs. Therefore, in the embodiment, a communication system is proposed that implements a mechanism for obtaining carrier setting information provided by the communications carrier to the device at the user's base from the cloud side, and a mechanism for the VoIP gateway to operate normally on the cloud side. The communication system of the embodiment is described in detail below.

Figure 4 shows the configuration of a communication system 100 according to an embodiment. In Figure 4, elements constituting the communication system 100 that are the same as or correspond to elements constituting the conventional communication system 10 shown in Figure 1 are denoted with the same reference numerals and explained. Furthermore, repeated explanations of content that has already been explained in relation to the conventional communication system 10 will be omitted as appropriate.

The difference between the communication system 10 of the embodiment and the conventional communication system 10 is that the communication system 100 of the embodiment has a router device 62 installed at the user site instead of the IP telephone adapter 42 and the VoIP gateway 44. The router device 62 is a communication device installed at the user site and connected to the carrier network 14.

In addition, in the communication system 100 of the embodiment, a gateway device 64 is installed in the service provider network 18 as a VoIP gateway on the cloud side. The gateway device 64 is connected to the router device 62 via the Internet 12, the carrier network 14, the relay device 38, and the ONU device 40. Therefore, an L3 (layer 3) switch 60 is further installed in the service provider network 18, which relays packets transmitted and received between the gateway device 64 and the router device 62 and the Internet 12.

Figure 5 is a block diagram showing the functional blocks of the gateway device 64 in Figure 4. Each block shown in the block diagram of this disclosure can be realized in hardware terms by computer processors, CPUs, memory and other elements, electronic circuits, and mechanical devices, and in software terms by computer programs, etc., but here, functional blocks realized by the cooperation of these are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various ways by combining hardware and software.

The gateway device 64 includes a carrier-side interface 70, a user-side interface 72, a control unit 74, and a storage unit 76. The carrier-side interface 70 is an interface for communicating with the router device 62 via the L3 switch 60. As described later in relation to FIG. 9, an IP address for PPP communication and an IP address for L2TP (Layer 2 Tunneling Protocol)/IPsec (Security Architecture for Internet Protocol) communication are set in the carrier-side interface 70. The user-side interface 72 is an interface for communicating with the PBX 52. An IP address for communicating with the PBX 52 is set in the user-side interface 72.

The control unit 74 executes various data processing operations to operate in the same manner as the IP telephone adapter 42 and the VoIP gateway 44 in FIG. 1. The control unit 74 transmits and receives data to and from the router device 62 via the carrier-side interface 70, and transmits and receives data to and from the PBX 52 via the user-side interface 72.

The storage unit 76 stores data referenced or updated by the control unit 74. The storage unit 76 includes a carrier setting information storage unit 78. The carrier setting information storage unit 78 stores carrier setting information provided by the communications carrier to the user base (in this embodiment, the router device 62) as a DHCP response.

The control unit 74 includes a carrier setting information acquisition unit 80, a tunnel setting unit 82, a registration unit 84, a message reception unit 86, and a message transfer unit 88. A computer program that implements the functions of these multiple functional blocks may be stored on a recording medium and installed in the storage (storage unit 76, etc.) of the gateway device 64 via the recording medium. Alternatively, the computer program may be downloaded via a network and installed in the storage of the gateway device 64. The processor of the gateway device 64 may perform the functions of the multiple functional blocks by reading the computer program into main memory and executing it.

The carrier setting information acquisition unit 80 is installed at the user site and functions as an acquisition unit that acquires the IP address of the communication device provided by the communication carrier to the communication device connected to the communication carrier's network and the IP address of the communication carrier's SIP server. In the embodiment, the carrier setting information acquisition unit 80 acquires from the router device 62 the carrier setting information included in the DHCP response provided to the router device 62 from the communication carrier's DHCP server 32. The carrier setting information here includes (1) the global IP address assigned to the router device 62, (2) network information (subnet mask, default gateway information, etc.), (3) SIP server 30 information (global IP address of the SIP server 30, etc.), and (4) the telephone number of the router device 62 that is predetermined by the communication carrier (specifically, a list of one or more telephone numbers assigned to the user site). The carrier setting information acquisition unit 80 stores the acquired carrier setting information in the carrier setting information storage unit 78.

The tunnel setting unit 82 negotiates with the router device 62 using a known method to establish an Internet VPN (Virtual Private Network) using L2TP/IPsec between the router device 62. Hereinafter, this virtual transmission path using the Internet VPN is also referred to as a "VPN tunnel."

The registration unit 84 generates a registration message (specifically, a SIP message including a registration request) that includes the global IP address of the router device 62 indicated by the carrier setting information stored in the carrier setting information storage unit 78, and that is addressed to the global IP address of the SIP server 30 indicated by the carrier setting information. The registration unit 84 passes the registration message to the router device 62 via the VPN tunnel, thereby causing the router device 62 to transmit the registration message to the carrier network 14 (SIP server 30).

The message reception unit 86 receives SIP messages (e.g., INVITE messages and various response messages) sent from the SIP server 30 to the router device 62 and forwarded from the router device 62 via the VPN tunnel.

The message forwarding unit 88 forwards the SIP message forwarded from the router device 62 (in other words, the SIP message accepted by the message accepting unit 86) to the PBX 52 of the service provider network 18. As a result, the message forwarding unit 88 causes the PBX 52 to execute processing to control the telephone terminal 46 installed at the user's base based on the SIP message.

The message transfer unit 88 accepts SIP messages (e.g., INVITE messages and various response messages) output from the PBX 52 to be sent to the SIP server 30, and converts the source IP address contained in the SIP message into the global IP address of the router device 62 indicated by the carrier setting information stored in the carrier setting information storage unit 78. This conversion is also referred to as "SIP-NAT" below. The message transfer unit 88 passes the SIP message after SIP-NAT to the router device 62 via the VPN tunnel, thereby causing the router device 62 to send the SIP message after SIP-NAT to the carrier network 14 (SIP server 30).

Figure 6 shows an example of a SIP message after SIP-NAT. The figure shows a SIP message 112 after SIP-NAT and an IP header 110 added to the SIP message 112. The IP header 110 is not subject to SIP-NAT. The IP address of the gateway device 64 is set in item 114 of the IP header 110.

On the other hand, SIP message 112 is subject to SIP-NAT. Items 116, 118, 120, 122, and 124 (collectively referred to as "target items") of SIP message 112 are set with the global IP address of router device 62 assigned by the communications carrier, in other words, the global IP address of router device 62 for carrier network 14. For example, the IP address of gateway device 64 may be set as the target item of the SIP message output from PBX 52. Message forwarding unit 88 may replace the value of the target item of the SIP message from the IP address of gateway device 64 to the global IP address of router device 62.

Although FIG. 6 shows an example of a SIP message including an INVITE request, the message transfer unit 88 also performs SIP-NAT on other types of SIP messages. For example, in the case of a SIP message including a registration request, the message transfer unit 88 converts the source IP address included in the contact header in the SIP message into the global IP address of the router device 62 indicated by the carrier setting information.

In this way, the message forwarding unit 88 of the gateway device 64 performs SIP-NAT, and the router device 62 sends the SIP message received from the gateway device 64 directly to the carrier network 14 (SIP server 30) without being aware of the contents of the SIP message. Since the correct IP address assigned by the communications carrier is set in the SIP message sent from the router device 62, the SIP server 30 recognizes the SIP message as valid and can execute the signaling process normally.

Figure 7 is a sequence diagram showing the operation of the communication system 100 of the embodiment. When the telephone terminal 36 is started, it executes a registration process to the SIP server 30. When the telephone terminal 46 is started, it executes a registration process to the PBX 52. When the router device 62 at the user's site is started, it sends a DHCP request to the DHCP server 32 (S10). The DHCP server 32 assigns a global IP address to the router device 62 and sends a DHCP response including carrier setting information to the router device 62 (S12).

The carrier setting information of the embodiment, like that of the prior art, includes (1) a global IP address assigned to the router device 62, (2) network information (subnet mask, default gateway information, etc.), (3) SIP server 30 information (global IP address of the SIP server 30, etc.), and (4) telephone number of the router device 62 predetermined by the communications carrier (specifically, a list of one or more telephone numbers assigned to user locations). The DHCP server 32 also notifies the SIP server 30 of the global IP address assigned to the router device 62. The SIP server 30 stores the line information (line ID, etc.) of the user location predetermined by the communications carrier in association with the global IP address of the router device 62.

The carrier setting information acquisition unit 80 of the gateway device 64 logs into the router device 62 using SSH (Secure Shell) (S14) and reads the carrier setting information provided by the communications carrier from the router device 62 (S16). The tunnel setting unit 82 of the gateway device 64 establishes an L2TP/IPsec connection (VPN tunnel) with the router device 62 (S18). After that, various data is sent and received between the router device 62 and the gateway device 64 via the VPN tunnel.

The registration unit 84 of the gateway device 64 sends a registration message to the router device 62 (S20). The router device 62 sends the registration message to the carrier network 14, and the registration message reaches the SIP server 30 via the carrier network 14 (S22). The SIP server 30 determines that the sender is a legitimate sender based on the global IP address of the router device 62 contained in the SIP message (contact header, etc.) and the line information from which the SIP message was sent, and executes the registration process for the SIP client. The SIP server 30 sends a SIP message indicating successful registration to the router device 62 (S24). When the router device 62 receives the SIP message indicating successful registration sent from the SIP server 30 from the carrier network 14, it forwards the SIP message to the cloud gateway device 64 (S26).

Below, we will explain an example of calling from a telephone terminal 36 located outside the user site to a telephone terminal 46 located within the user site. The telephone terminal 36 sends an INVITE message specifying the telephone number of the user site to the SIP server 30 (S28). The SIP server 30 sends the INVITE message to a router device 62 at the user site according to the specified telephone number (S30). When the router device 62 receives the SIP message sent from the SIP server 30 from the carrier network 14, it forwards the INVITE message to a cloud gateway device 64 (S32).

The message forwarding unit 88 of the gateway device 64 forwards the INVITE message forwarded from the router device 62 to the PBX 52 (S34). The PBX 52 executes signaling processing for the telephone terminal 46 installed at the user's site based on the SIP message forwarded from the gateway device 64. Specifically, the PBX 52 determines the telephone terminal 46 to receive the call based on the telephone number specified in the INVITE message forwarded from the gateway device 64. The PBX 52 sends the INVITE message to the telephone terminal 46 determined as the destination (S36).

After processing S34, the message forwarding unit 88 of the gateway device 64 sends a SIP message indicating that processing is in progress (100 trying) to the router device 62 (S38), and the router device 62 forwards the SIP message to the carrier network 14 (S40), whereupon the SIP message reaches the SIP server 30. The SIP server 30 sends a SIP message indicating that processing is in progress to the telephone terminal 36 (S42). After processing S36, the PBX 52 sends a SIP message indicating that processing is in progress to the gateway device 64 (S44). The telephone terminal 46 sends a SIP message indicating that processing is in progress to the PBX 52 (S46).

Figure 8 is a sequence diagram showing the operation of the communication system 100 following Figure 7. The telephone terminal 46 sends a SIP message indicating that a call is being called (180 Ringing) to the PBX 52 (S48). The PBX 52 sends a SIP message indicating that a call is being called to the gateway device 64 (S50). The message forwarding unit 88 of the gateway device 64 sends a SIP message indicating that a call is being called to the router device 62 (S52), which forwards the SIP message to the carrier network 14 (S54), and the SIP message reaches the SIP server 30. The SIP server 30 sends a SIP message indicating that a call is being called to the telephone terminal 36 (S56).

The telephone terminal 36 transmits a SIP message indicating a PRACK request (hereinafter also referred to as a "PRACK message") to the SIP server 30 (S58). The SIP server 30 transmits the PRACK message to the router device 62 (S60), and the router device 62 transfers the PRACK message to the gateway device 64 (S62). The gateway device 64 transmits a response message indicating a response to the PRACK message (200 OK (PRACK)) to the router device 62 (S64), and the router device 62 transfers the response message to the carrier network 14 (S66), and the response message reaches the SIP server 30. The SIP server 30 transmits the response message to the telephone terminal 36 (S68).

When the person in charge at the user site answers the phone, the telephone terminal 46 sends a response message to the PBX 52 (S70). The PBX 52 sends the response message to the gateway device 64 (S72). The message forwarding unit 88 of the gateway device 64 sends the response message to the router device 62 (S74), which forwards the response message to the carrier network 14 (S76), and the response message reaches the SIP server 30. The SIP server 30 sends the response message to the telephone terminal 36 (S78).

After processing S74, the message forwarding unit 88 of the gateway device 64 sends an ACK message to the PBX 52 (S80), and the PBX 52 sends the ACK message to the telephone terminal 46 (S82). The telephone terminal 36 also sends the ACK message to the SIP server 30 (S84). The SIP server 30 sends the ACK message to the router device 62 (S86), and the router device 62 forwards the ACK message to the gateway device 64 (S88). Through the above signaling processing, RTP sessions for voice calls are established (1) between the telephone terminal 36 and the router device 62, (2) between the router device 62 and the gateway device 64, and (3) between the gateway device 64 and the telephone terminal 46.

When voice is input to the telephone terminal 46, the telephone terminal 46 transmits an RTP packet including the voice data to the gateway device 64 (S90). The message transfer unit 88 of the gateway device 64 transmits the RTP packet including the voice data to the router device 62 (S92). The router device 62 transmits the RTP packet received from the gateway device 64 to the carrier network 14 (S94). As a result, the RTP packet reaches the telephone terminal 36, and the voice is output at the telephone terminal 36.

On the other hand, when voice is input to the telephone terminal 36, the telephone terminal 36 transmits an RTP packet including the voice data to the router device 62 via the carrier network 14 (S96). The router device 62 transfers the RTP packet received from the telephone terminal 36 to the gateway device 64 (S98). The message transfer unit 88 of the gateway device 64 transmits the RTP packet including the voice data to the telephone terminal 46 (S100). As a result, the voice is output from the telephone terminal 46.

Figure 9 shows an example of communication via a VPN tunnel. A first IP address (X.X.7.74) (global IP address) provided by the communications carrier in the DHCP response (carrier setting information) and a second IP address (Y.Y.226.143) (global IP address) predetermined for communication with the gateway device 64 are set in the router device 62 at the user site. In addition, a first IP address (192.168.100.222) for PPP communication and a second IP address (Z.Z.181.12) (global IP address) for L2TP/IPsec communication are set in the gateway device 64 of the service provider network 18.

The communication carrier's SIP server 30 transmits a SIP packet 130 including a SIP message to the router device 62. The router device 62 executes NAT processing to rewrite the destination IP address of the SIP packet 130 to the first IP address of the gateway device 64, and generates an L2TP packet 136 in which the SIP packet 132 is encapsulated by adding an L2TP header 134 to the SIP packet 132 after the NAT processing. The L2TP header 134 here has the second IP address of the gateway device 64 as its destination and the second IP address of the router device 62 as its source. The router device 62 transmits the L2TP packet 136 to the gateway device 64.

When the message reception unit 86 of the gateway device 64 receives the L2TP packet 136, it decapsulates the L2TP packet 136 by removing the L2TP header 134 from the L2TP packet 136. The message reception unit 86 passes the decapsulated SIP packet 132 to subsequent processing (e.g., the message transfer unit 88).

When the message transfer unit 88 of the gateway device 64 receives a SIP message output from the PBX 52 to be sent to the SIP server 30, it generates a SIP packet 140 by adding an IP header with the IP address of the SIP server 30 as the destination and the first IP address of the gateway device 64 as the source. The message transfer unit 88 generates an L2TP packet 144 that encapsulates the SIP packet 140 by adding an L2TP header 142 to the SIP packet 140. The L2TP header 142 here has the second IP address of the router device 62 as the destination and the second IP address of the gateway device 64 as the source.

The message transfer unit 88 of the gateway device 64 transmits the L2TP packet 144 to the router device 62. When the router device 62 receives the L2TP packet 144, it decapsulates the L2TP packet 144 by removing the L2TP header 142 from the L2TP packet 144. The router device 62 performs NAT processing to rewrite the source IP address of the decapsulated SIP packet 140 to the first IP address of the router device 62. The router device 62 transmits the NAT processed SIP packet 146 to the carrier network 14.

In this way, by connecting the gateway device 64 and the router device 62 via a VPN, SIP messages to be sent to the SIP server 30 can be reliably sent from the router device 62 to the SIP server 30. In other words, SIP messages to be sent from the gateway device 64 to the SIP server 30 can be sent to the SIP server 30 using a source IP address and line that the SIP server 30 judges to be valid. Note that while FIG. 9 shows an example of communication of SIP packets, the same applies to communication of RTP packets, and in this case, the SIP server 30 is replaced with the telephone terminal 36.

According to the communication system 100 of the embodiment, a gateway device 64 that behaves in the same manner as an IP telephone adapter 42 and a VoIP gateway 44 conventionally installed at a user's site can be realized on the cloud (service provider network 18 in the embodiment) for each of the SIP server 30 of the carrier network 14 and the PBX 52 of the service provider network 18. By paying a specified usage fee, the user can use the functions of the gateway device 64, eliminating the need to install an expensive VoIP gateway 44 at the user's site and to maintain the VoIP gateway 44. In other words, according to the communication system 100 of the embodiment, it is possible to achieve both the continued use of the telephone number (area number) of the user's site and the inexpensive use of a cloud PBX.

The present invention has been described above based on examples. These examples are merely illustrative, and those skilled in the art will understand that various modifications are possible in the combinations of the components and processing processes described in the examples, and that such modifications are also within the scope of the present invention.

In the above embodiment, (1) the global IP address assigned to the router device 62, (2) network information (subnet mask, default gateway information, etc.), (3) SIP server 30 information (global IP address of the SIP server 30, etc.), and (4) the telephone number of the router device 62 predefined by the communication carrier (specifically, a list of one or more telephone numbers assigned to the user's base) are dynamically acquired from the communication carrier's device as a DHCP response. As a variant, the carrier setting information for the user may be statically predefined by the communication carrier and provided/notified to the user in advance by the communication carrier. The statically predefined carrier setting information may be stored in the router device 62 and the gateway device 64 (carrier setting information storage unit 78) by the system builder and stored in the router device 62 and the gateway device 64 (carrier setting information storage unit 78). The gateway device 64 may use the statically predefined carrier setting information stored in the carrier setting information storage unit 78 to process the SIP message (e.g., generate/transmit a registration message to the SIP server 30, etc.).

Of course, there is no limit to the number of physical housings for each device in the communication system 100 of the above embodiment. For example, each device shown in FIG. 4 (e.g., gateway device 64) may be realized as a system in which multiple devices work together.

Any combination of the above-mentioned examples and modifications is also useful as an embodiment of the present invention. A new embodiment resulting from the combination will have the combined effects of each of the examples and modifications. It will also be understood by those skilled in the art that the functions to be performed by each of the constituent elements recited in the claims can be realized by each of the constituent elements shown in the examples and modifications alone or in combination with each other.

30 SIP server, 36 telephone terminal, 46 telephone terminal, 52 PBX, 62 router device, 64 gateway device, 80 carrier setting information acquisition unit, 84 registration unit, 86 message reception unit, 88 message transfer unit, 100 communication system.

Claims (6)

A gateway device provided at a location different from a user's base,
an acquisition unit that is installed at the user's base and that acquires an IP address of a communication device provided by the communication carrier for a communication device connected to a network of the communication carrier, and an IP address of a Session Initiation Protocol (SIP) server of the communication carrier;
a registration unit that delivers a registration message including an IP address of the communication device and addressed to the IP address of the SIP server to the communication device and transmits the registration message from the communication device to a network of the communication carrier;
a reception unit that receives a SIP message transmitted from the SIP server to the communication device and forwarded from the communication device;
a transfer unit that transfers the SIP message transferred from the communication device to an exchange that is provided at a location different from the user's base and that controls a telephone terminal provided at the user's base;
A gateway device comprising: The gateway device according to claim 1, characterized in that the forwarding unit converts the source IP address included in the SIP message output from the exchange to be sent to the SIP server into the IP address of the communication device provided by the communication carrier, passes the converted SIP message to the communication device, and transmits the converted SIP message from the communication device to the network of the communication carrier. In addition to a first IP address provided by the communication carrier, a second IP address different from the first IP address is further set in the communication device for communicating with the gateway device;
The gateway device according to claim 1 or 2, characterized in that the forwarding unit generates a packet encapsulating a SIP message to be sent to the SIP server by adding a header destined for the second IP address of the communication device to the SIP message destined for the SIP server, and by sending the packet to the communication device, causes the SIP message after the packet encapsulation to be sent from the communication device to the communication carrier's network. A gateway device provided at a location different from a user's base,
a storage unit that stores information provided by a communication carrier, the information including an IP address of a communication device installed at a base of the user and connected to a network of the communication carrier, and an IP address of a SIP server of the communication carrier;
a registration unit that delivers a registration message including an IP address of the communication device and addressed to the IP address of the SIP server to the communication device and transmits the registration message from the communication device to a network of the communication carrier;
a reception unit that receives a SIP message transmitted from the SIP server to the communication device and forwarded from the communication device;
a transfer unit that transfers the SIP message transferred from the communication device to an exchange that is provided at a location different from the user's base and that controls a telephone terminal provided at the user's base;
A gateway device comprising: A communication device installed at a user's base and connected to a communication carrier's network;
An exchange provided at a location different from the user's base;
A gateway device provided at a location different from the user's base;
Equipped with
the gateway device acquires an IP address of the communication device provided by the communication carrier and an IP address of a SIP server of the communication carrier;
the gateway device passes to the communication device a registration message including an IP address of the communication device and addressed to the IP address of the SIP server;
The communication device transmits the registration message to the communication carrier's network;
When the communication device receives a SIP message from the SIP server, the communication device transfers the SIP message to the gateway device;
The gateway device transfers the SIP message transferred from the communication device to the exchange;
The communication system according to the present invention is characterized in that the exchange controls telephone terminals provided at the user's bases based on the SIP messages transferred from the gateway device. A communication device installed at a user's base and connected to a communication carrier's network;
An exchange provided at a location different from the user's base;
A gateway device provided at a location different from the user's base;
Equipped with
the gateway device stores information provided by the communication carrier, the information including an IP address of the communication device and an IP address of a SIP server of the communication carrier;
the gateway device passes to the communication device a registration message including an IP address of the communication device and addressed to the IP address of the SIP server;
The communication device transmits the registration message to the communication carrier's network;
When the communication device receives a SIP message from the SIP server, the communication device transfers the SIP message to the gateway device;
The gateway device transfers the SIP message transferred from the communication device to the exchange;
The communication system according to the present invention is characterized in that the exchange controls telephone terminals provided at the user's bases based on the SIP messages transferred from the gateway device.

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