JP2014023027A - Ip telephone system, ip trunk gateway device and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To build a connection environment with an IP trunk inexpensively without limiting the type of available NAT routers.SOLUTION: An IP telephone system includes a plurality of telephone terminals, an NAT router, and an IP trunk gateway device. The IP trunk gateway device includes storage means, message generation means, and message communication means. The storage means stores the address information of the IP trunk gateway device when viewed from a second communication network side. The message generation means sets the address information stored in the storage means in a call connection control message being transmitted toward the IP trunk when a call connection request with the IP trunk is generated at the telephone terminal on a first communication network. The message communication means communicates a call connection control message generated by the message generation means between the IP trunk.

Description

  Embodiments described herein relate generally to an IP telephone system, an IP trunk gateway device, and a method for controlling an IP trunk gateway device.

  In recent years, IP telephone systems that transmit and receive images and sounds as packet data in both directions via an IP network have become widespread. In this IP telephone system, a plurality of IP telephone terminals are accommodated in an IP trunk gateway apparatus via a LAN (Local Area Network), and also in a WAN (Wide Area Network) such as a public network or the Internet via a LAN and a router apparatus. Connectable. Then, by performing address conversion or the like in the router device, multimedia information communication can be performed between IP telephone terminals and between an IP telephone terminal and a WAN.

  By the way, in the above system, a NAT (Network Address Translator) function is installed in the router device. The NAT function uses a single IP address pre-assigned for connection, converts a local address for LAN to a global address for WAN, sends it as a source IP address, and supplies a destination IP supplied in reception This function converts a global address to a local address.

US 7,068,647 B2

  By the way, in order to connect an IP trunk gateway device using a call control message to an IP trunk on a WAN via a NAT router, an ALG (application layer) corresponding to the protocol between the IP trunk gateway device and the IP trunk is used. It is necessary to rewrite the address information in the call control message by the gateway.

  However, since NAT routers having an ALG function are limited in the types of NAT routers that can be used and are expensive, for example, they are costly to install in a small office.

  An object of the present invention is to provide an IP telephone system, an IP trunk gateway device, and a control method capable of constructing a connection environment with an IP trunk at a low cost without limiting the types of NAT routers that can be used.

  According to the embodiment, the IP telephone system includes a plurality of telephone terminals connected to the first communication network, a NAT router, and an IP trunk gateway device. The NAT router connects the first communication network and the second communication network. The IP trunk gateway device accommodates a plurality of telephone terminals via the first communication network, and can connect an IP (Internet Protocol) trunk on the second communication network via the first communication network and the NAT router. To do. In addition, the IP trunk gateway device includes storage means, message generation means, and message communication means. The storage means stores the address information of the IP trunk gateway device as viewed from the second communication network side. The message generation means includes the address information stored in the storage means in the call connection control message transmitted to the IP trunk when a call connection request with the IP trunk is generated at the telephone terminal on the first communication network. Set. The message communication unit communicates the call connection control message generated by the message generation unit with the IP trunk.

1 is a schematic configuration diagram showing an IP telephone system according to the present embodiment. The block diagram which shows the function structure of the SIP server shown in the said FIG. The figure which shows an example of the memory content of the address information table shown in the said FIG. The figure which shows an example of the format of the INVITE message used by this embodiment. The sequence diagram which shows the operation | movement which establishes a communication session between an IP telephone terminal and the telephone terminal on a SIP trunk in this embodiment. The sequence diagram which shows the operation | movement inside the SIP server in this embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
In this embodiment, a SIP (Session Initiation Protocol) server as an IP trunk gateway device is connected to a SIP trunk on a WAN using a NAT router without ALG.

  For example, it is assumed that an IP telephone terminal accommodated in a SIP server makes a call to a terminal on a SIP trunk. Then, the local IP address and port number in the SIP message sent from the SIP server to the SIP trunk are not converted by the NAT router. For this reason, if the terminal on the SIP trunk that has received the SIP message tries to send the SIP message back to the transmission source using the local IP address and port number in the SIP message, the destination cannot be correctly specified. No SIP message reaches the sender.

  Therefore, in this embodiment, before the SIP message is transmitted to the SIP trunk by the SIP server, the local IP address of the transmission source in the SIP message is replaced with the global IP address of the SIP server viewed from the SIP trunk side. Yes.

  FIG. 1 is a schematic configuration diagram showing an IP telephone system according to the present embodiment.

  This system has a LAN1. IP telephone terminals T11 to T1i are connected to the LAN1. IP telephone terminals T11 to T1i are terminals having a call processing function and a media information processing function, or a soft phone realized by software on a personal computer.

  In addition, terminals T21 to T2m are connected to the LAN 1 via the access point AP1 and the wireless LAN. The terminals T21 to T2m are portable telephone terminals that can be connected to a wireless LAN and are driven by a battery.

  Further, gateways GW1 to GW3 are connected to the LAN1. The gateway GW1 connects between the LAN1 and the telephone terminals T31 to T3n, and has a communication protocol and signal format conversion function between the LAN1 and the telephone terminals T31 to T3n. The gateway GW2 connects between the LAN1 and the telephone terminals T41 to T4p or a public network PNW such as an analog telephone network. The communication protocol and signal format between the LAN1 and the telephone terminals T41 to T4p or the public network PNW It has a conversion function. The gateway GW3 connects between the LAN1 and the public network PNW and has a function of converting a communication protocol and a signal format between the LAN1 and the public network PNW. For the telephone terminals T31 to T3n and T41 to T4p, analog telephones, digital button telephones, and the like are used.

  Furthermore, a SIP server SV1 is connected to the LAN1. The SIP server SV1 is connected between the IP telephone terminals T11 to T1i, the access point AP1, and the gateways GW1 to GW3, for example, SIP, Megaco, H.P. An exchange control function for establishing a session according to a predetermined protocol such as H.323 is provided. Then, voice communication is performed by transmitting and receiving IP packets by peer-to-peer connection between the IP telephone terminal on the caller side and the callee side through the established session.

  The server SV2 is connected to the SIP server SV1 via the WAN2. The SIP server SV1 has an exchange control function for establishing a session with the server SV2 in accordance with, for example, IP-QSIG. Then, after the session is established, voice communication is performed by transmitting and receiving IP packets by peer-to-peer connection between the telephone terminal on the caller side and the callee side.

  Further, a SIP trunk INW is connected to the SIP server SV1 via the NAT router RT1 and WAN3. The SIP server SV1 has an exchange control function for establishing a session with the SIP trunk INW according to, for example, SIP. Then, after the session is established, voice communication is performed by transmitting and receiving IP packets by peer-to-peer connection between the telephone terminal on the caller side and the callee side.

  Incidentally, the SIP server SV1 has the following functions as functions according to the present embodiment. FIG. 2 is a block diagram showing the configuration.

  The SIP server SV1 includes a control unit 21, a north bridge 22, a main memory 23, a south bridge 26, an HDD (Hard Disk Drive) 27, a multi drive 28, a LAN controller 29, an interface unit 30, a PC card controller 31, a BIOS-ROM ( A basic input / output system ROM (33), an EC / KBC (embedded controller / keyboard controller) 34, a power supply controller (PSC) 35, a power supply unit 36, an interface (I / F) 38, an I / O controller 40, and the like.

The control unit 21 is responsible for overall control of the SIP server SV1 with (CPU: Central Processing Unit) as the main body, and uses the main memory 23 as a work area and is loaded from the HDD 27 to the main memory 23. OS) 23a, driver 23b, exchange program 23c, and the like are executed.
The north bridge 22 includes various controllers that perform bridge processing between the control unit 21 and the south bridge 26, control of the main memory 23, and the like.
The south bridge 26 is connected to the north bridge 22 via a hub link, and various devices (EC / KBC 34, I / O controller, etc.) on an LPC (Low Pin Count) bus and a PCI (Peripheral Component Interconnect) bus. Various controllers for controlling the above various PCI devices (LAN controller 29, interface unit 30, PC card controller 31 and the like), IDE (Integrated Drive Electronics) compatible disk drives, USB devices and the like are provided.

  The HDD 27 is connected to the south bridge 26 as a device corresponding to the primary IDE, and is a built-in hard disk that stores various programs such as an OS and an exchange program, various data 23d, and the like. The multi-drive 28 is connected to the south bridge 26 as a device corresponding to the secondary IDE, and drives a CD-ROM, DVD-ROM, and CD-R / RW which are removable recording media.

The LAN controller 29 is connected to the south bridge 26 as a PCI device, has a communication function conforming to the specification of the wired LAN, and communicates with a communication apparatus having the same communication function.
The interface unit 30 is connected to the south bridge 26 as a PCI device, has a communication function conforming to the specifications of the LAN 1, and performs processing related to exchange of RTP packets.
The PC card controller 31 is connected to the south bridge 26 as a PCI device, and controls various PC cards in accordance with the specification of PCMCIA (Personal Computer Memory Card International Association). The BIOS-ROM 33 is connected to the LPC bus and stores a BIOS (Basic Input / Output System) that mainly performs setting processing for hardware in the SIP server SV1 when the power is turned on. The EC / KBC 34 is connected to the LPC bus and controls the power controller 35 and the like. The EC / KBC 34 is obtained by integrating an embedded controller (EC) that is an embedded controller and a keyboard controller.

  The power supply controller 35 is connected to the EC / KBC 34 via the I2C bus and controls the voltage supplied to each part in the SIP server SV1. The power supply unit 36 generates drive power and supplies it to each unit in the SIP server SV1. The interface 38 can be connected to an input device or the like, and performs signal interface with the EC / KBC 34. The I / O controller 40 is connected to the LPC bus and performs input / output control of serial signals and parallel signals with the outside.

  In the SIP server SV1, under the control of the control unit 21, the exchange program 23c developed on the main memory 23 implements a predetermined exchange processing function in cooperation with the LAN controller 29 and the like. The SIP server SV1 loads the exchange program 23c on a general-purpose computer server and executes the program to realize the exchange function between telephone terminals. The SIP server SV1, like a general-purpose computer, is a virtual storage system that makes it appear that it is continuous when viewed from software (process etc.) even if the area where data is stored is a physically discontinuous memory area. adopt.

  Incidentally, the data area 23d of the main memory 23 is provided with an address information table 23d1. The address information table 23d1 is a table for managing the global IP address and port number of the SIP server SV1 viewed from the WAN3 side. In the address information table 23d1, as shown in FIG. 3, the global IP address “98.174.157.246” and the port number “5060” are stored in advance.

  In addition, the control unit 21 includes a SIP message generation unit 21a, a SIP message transmission unit 21b, and a SIP message reception unit 21c. The SIP message generating unit 21a, for example, when a call request as a call connection request to the SIP trunk INW is generated in the IP telephone terminal T11 on the LAN 1, for example, a Contact header in the INVITE message to be transmitted to the SIP trunk INW, Via The global IP address and port number stored in the address information table 23d1 are set in the header. Further, the global IP address stored in the address information table 23d1 is set in the host area of the From header and the host area of the CallID header.

  FIG. 4 shows an example of the format of the INVITE message. The INVITE message is composed of a Request-Line, a message header, and a message body. The To-header field in the Request-Line, message header includes information indicating the terminal on the SIP trunk INW as destination information. The Via header field in the message header includes the global IP address and port number of the SIP server SV1. The From header field in the message header includes the extension number and global IP address of the SIP server SV1. The CallID header field in the message header includes the extension number of the transmission source and the global IP address of the SIP server SV1. The Contact header field in the message header includes the extension number, global IP address, and port number of the SIP server SV1.

  SDP information and session ID are inserted into the message body. The session ID includes the global IP address of the SIP server SV1.

  The SIP message transmission unit 21b transmits the INVITE message generated by the SIP message generation unit 21a toward the SIP trunk INW.

  In response to the transmission of the INVITE message, the SIP message receiving unit 21c receives a 100 Trying message, a 180 Ringing message, and a 200 OK message returned from the SIP trunk INW.

Next, the operation in the above configuration will be described.
First, an operation for establishing a communication session between the IP telephone terminal T12 and the telephone terminal TT1 on the SIP trunk INW will be described. FIG. 5 is a sequence diagram showing an operation for establishing a communication session between the IP telephone terminal T12 and the telephone terminal TT1 on the SIP trunk INW, and FIG. 6 is a sequence diagram showing an internal operation of the SIP server SV1. .

  Now, as shown in FIG. 5, it is assumed that the user of the IP telephone terminal T12 performs a call operation to the telephone terminal TT1 on the SIP trunk INW (FIG. 5 (1)). Then, the call request and the dial “◯ △ ○” are sent from the IP telephone terminal T12 to the SIP server SV1 (FIG. 5 (2)).

  When the SIP server SV1 receives the transmission request and the dial “◯ △ ○”, the control unit 21 sends a SIP message transmission request to the SIP message generation unit 21a (FIG. 6 (1)), and the SIP message generation unit 21a. Acquires the address information from the address information table 23c1 and sets it in the INVITE message ((2) in FIG. 6). In this case, the address information in the address information table 23c1 is set in the Contact header, which is one of the message headers in the INVITE message, in place of the local IP address and port number of the source IP telephone terminal T12.

  Thereafter, the SIP message generation unit 21a instructs the SIP message transmission unit 21b to transmit and transmits the INVITE message ((3) in FIG. 6). The INVITE message reaches the SIP trunk INW without undergoing address translation at the NAT router RT1 (FIG. 5 (3)). Then, the destination telephone terminal TT1 is called.

  When receiving the INVITE message, the SIP trunk INW holds the WAN side IP address and port number of the NAT router RT1 as address information of the SIP server SV1.

  The NAT router RT1 is set to convert a port used for transmission / reception of the SIP message to the local IP address of the SIP server SV1 as a static forwarding setting.

  Then, the SIP trunk INW returns a 100 Trying message and a 180 Ringing message indicating that the incoming call notification is being performed to the SIP server SV1 (FIGS. 5 (4) and (5)). In this case, the WAN side IP address and the port number of the NAT router RT1 that are held are set in the Contact header. The NAT router RT1 transfers the received 100 Trying message and 180 Ringing message to the local IP address of the SIP server SV1 according to the static forwarding setting.

  As a result, the SIP message reaches the SIP server SV1 from the SIP trunk INW without the SIP ALG function.

  When the user of the destination telephone terminal TT1 responds to the incoming call notification (FIG. 5 (6)), the SIP trunk INW transmits a response message (200 OK) to the SIP server SV1 (FIG. 5 (7)). . The WAN side IP address and the port number of the NAT router RT1 held are also set in the Contact header of this response message (200 OK). Upon receiving the response message (200 OK), the SIP server SV1 returns an ACK indicating that the response message (200 OK) has been accepted to the SIP telephone terminal T21 (FIG. 5 (8)). At this time, the SIP server SV1 also sets the global IP address and port number stored in the address information table 23c1 in the Contact header of ACK.

  Thus, a communication session is formed between the originating IP telephone terminal T12 and the telephone terminal TT1 on the destination SIP trunk INW, and thereafter, RTP packets are transmitted and received to enable a call (FIG. 5 ( 9)).

  On the other hand, even when a call is made between the IP telephone terminal T13 and the telephone terminal accommodated in the server SV2 on the WAN2, the SIP server SV1 is, for example, a message header in an IP-QSIG SETUP message that becomes an occurrence request message. And the global IP address and port number of the SIP server SV1 are set in the message body.

  As described above, in the above embodiment, the call connection control is performed by storing the global IP address and port number of the SIP server SV1 viewed from the WAN3 side of the NAT router RT1 in the address information table 23c1 in the SIP server SV1 in advance. When sending a SIP message as a message to the SIP trunk INW, it is only necessary to set the global IP address and port number stored in the address information table 23c1 in the Contact header in the SIP message. Rewriting of the address information inside is unnecessary.

  Therefore, by connecting the SIP server SV1 to the SIP trunk INW on the WAN3 using a NAT router without an ALG function, it becomes possible to use all kinds of NAT routers and build an environment for connecting to an IP trunk at a low cost. it can.

  Note that the present embodiment is not limited to the SIP trunk INW, but can also be applied to a case where the SIP server SV1 is connected to an IP trunk other than SIP via a NAT router.

  Furthermore, in the above-described embodiment, the example in which the global IP address and the port number of the SIP server SV1 are set in the Contact header in the SIP message has been described. However, it may be set in the Via header. Furthermore, a global IP address may be set in the host area of the From header or the host area of the CallID header.

(Other embodiments)
Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... LAN, 2, 3 ... WAN, 21 ... Control part, 22 ... North bridge, 23 ... Main memory, 26 ... South bridge, 27 ... HDD, 28 ... Multi drive, 29 ... LAN controller, 30 ... Interface part, 31 ... PC card controller, 33 ... BIOS-ROM, 34 ... EC / KBC, 35 ... Power supply controller, 36 ... Power supply unit, 21a ... SIP message generation unit, 21b ... SIP message transmission unit, 21c ... SIP message reception unit, 23d1 ... Address information table, SV1... SIP server, T11 to T1i... IP telephone terminal, AP1... Access point, T21 to T2m... Terminal, RT1 ... NAT router, GW1 to GW3 ... gateway, INW ... SIP trunk, PNW.

Claims (15)

A plurality of telephone terminals connected to a first communication network, a NAT (Network Address Translator) router that connects the first communication network and the second communication network, and the plurality of telephone terminals for a first communication An IP trunk gateway device that is accommodated via a network and is capable of connecting an IP (Internet Protocol) trunk on the second communication network via the first communication network and a NAT router,
The IP trunk gateway device is:
Storage means for storing address information of the IP trunk gateway device viewed from the second communication network side;
Address information stored in the storage means is set in a call connection control message transmitted to the IP trunk when a call connection request with the IP trunk is generated at a telephone terminal on the first communication network Message generating means for
An IP telephone system comprising message communication means for communicating a call connection control message generated by the message generation means with the IP trunk. The storage means stores an IP address and a port number of the IP trunk gateway device viewed from the second communication network,
2. The IP telephone system according to claim 1, wherein the message generation unit sets an IP address and a port number stored in the storage unit in a call connection control message transmitted to the IP trunk.   The IP telephone system according to claim 1, wherein the IP trunk is based on a SIP protocol.   4. The IP telephone according to claim 3, wherein the message generation means sets address information stored in the storage means in a Contact header or a Via header of the call connection control message when the call connection control message is defined by SIP. system.   The message generation means sets the address information stored in the storage means in the host area of the From header or the CallID header of the call connection control message when the call connection control message is defined by SIP. Item 5. The IP telephone system according to Item 4. A plurality of telephone terminals can be accommodated via a first communication network, and an IP (Internet Protocol) trunk on the second communication network can be connected via the first communication network and a NAT (Network Address Translator) router. In the IP trunk gateway device,
Storage means for storing address information of the IP trunk gateway device viewed from the second communication network;
Address information stored in the storage means is set in a call connection control message transmitted to the IP trunk when a call connection request with the IP trunk is generated at a telephone terminal on the first communication network Message generating means for
An IP trunk gateway apparatus comprising message communication means for communicating a call connection control message generated by the message generation means with the IP trunk. The storage means stores an IP address and a port number of the IP trunk gateway device viewed from the second communication network,
7. The IP trunk gateway device according to claim 6, wherein the message generation unit sets an IP address and a port number stored in the storage unit in a call connection control message transmitted to the IP trunk.   The IP trunk gateway apparatus according to claim 6, wherein the IP trunk is based on a SIP protocol.   9. The IP trunk according to claim 8, wherein when the call connection control message is defined by SIP, the message generation unit sets address information stored in the storage unit in a Contact header or a Via header of the call connection control message. Gateway device.   The message generation means sets the address information stored in the storage means in the host area of the From header or the CallID header of the call connection control message when the call connection control message is defined by SIP. Item 10. The IP trunk gateway device according to Item 9. A plurality of telephone terminals can be accommodated via a first communication network, and an IP (Internet Protocol) trunk on the second communication network can be connected via the first communication network and a NAT (Network Address Translator) router. In the control method of the IP trunk gateway device,
Storing the address information of the IP trunk gateway device viewed from the second communication network in a memory;
The address information stored in the memory is set in a call connection control message transmitted to the IP trunk when a call connection request to the IP trunk is generated at a telephone terminal on the first communication network. ,
A control method for an IP trunk gateway device for communicating a call connection control message in which the address information is set with the IP trunk. The storing stores the IP address and port number of the IP trunk gateway device viewed from the second communication network in a memory;
12. The method for controlling an IP trunk gateway apparatus according to claim 11, wherein the setting of the address information sets an IP address and a port number stored in the storage means in a call connection control message transmitted to the IP trunk.   12. The method of controlling an IP trunk gateway device according to claim 11, wherein the IP trunk is based on a SIP protocol.   The address information is set by setting address information stored in the memory in a Contact header or a Via header of the call connection control message when the call connection control message is defined by SIP. A method for controlling an IP trunk gateway device.   The address information is set by setting the address information stored in the memory in the host area of the From header or the CallID header of the call connection control message when the call connection control message is defined by SIP. The method for controlling an IP trunk gateway device according to claim 14.

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