KR101017497B1 - SIP message processing apparatus, NAT-TrEaRrEsr system and method - Google Patents

Abstract

A SIP message processing apparatus is provided. The SIP message processing apparatus includes a first interface unit for receiving a SIP message from an originating terminal, a second interface unit for transmitting a SIP message to a called terminal, a controller for analyzing whether the originating terminal is in a NAT environment by analyzing the SIP message, and the originating unit. If the terminal is in a NAT environment, the first address assigned to the calling terminal in the private network included in the SIP message and the second address assigned to the calling terminal in the NAT are transmitted to the media relay unit, and for the first address and the second address, And a third interface unit for requesting an address allocation for the media relay to the media relay unit.

NAT, IMS, IBCF, TrGW

Description

SIP message processing device, NAT-Tr eArchite system and method {Device for managing SIP message, system and method for NAT-Traversal}

The present invention relates to SIP interworking of a network having a private IP address, and more particularly, a SIP message processing device and NAT-Traversal in IMS, which applies an interworking interworking service between a PC or a mobile terminal on a web to an IMS network. System and method.

Increasing demand for packet-switched web-based clients to circuit-switched mobile terminals (Web to Phone services) or packet-switched web-based clients (Web to Web services) The trend is. Such Web to Phone service or Web to Web service should be able to provide unconditional service among members who are logged in regardless of operators of wired and wireless networks. To this end, an address translation apparatus for enabling SIP interworking of a network having a private IP address is required.

In general, network address translation (NAT) allows routing and packet reception from an external IP network by temporarily assigning a public IP address for each application of a terminal and translating the headers of all packets passing through it. Play a role. That is, when a terminal assigned a private IP address that can be used only in a local network uses an external public network, NAT uses a private IP address assigned to the terminal as a public IP address and a public IP address as a private IP address. To convert to and from. In addition, as one NAT, Port Address Translation (PAT) translates not only IP addresses but also port numbers of TCP / UDP. NAT may exist as a separate independent device, but generally exists as a function of a router.

However, such a NAT can analyze only the headers of the third and fourth layers of the OSI model and not the headers of the upper layer. In Session Initiation Protocol (SIP) -based session setup, which is a method of exchanging receiving address (IP and port) information that receives media between terminals of a network end, it is a private IP inside a NAT. The terminal assigned the address performs the SIP-based service with the external network. In this case, only the port value of the IP address and the UDP / TCP header are converted by the NAT, and the destination address in the SIP header, that is, the translation of the recognition information of the packet generating host set to the private IP is not possible. A situation arises in which incoming routing from a network is impossible. This is called a problem with NAT-Traversal.

However, such a problem of NAT-Traversal occurs in the interworking process of other networks in the IMS network, and therefore, a method of solving the NAT-Traversal problem in the IMS network is required.

Another object of the present invention is to provide a SIP message processing apparatus used in a manganese interworking method capable of solving the NAT-Traversal problem.

In addition, another technical problem to be achieved by the present invention is to provide a NAT-Traversal system that implements a manganese interworking method that can solve the NAT-Traversal problem.

Another technical problem to be achieved by the present invention is to provide a NAT-Traversal method using the IBCF / TrGW system in IMS, which can solve the NAT-Traversal problem in the IMS network.

The object of the present invention is not limited to the above-mentioned object, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, a SIP message processing apparatus according to an embodiment of the present invention includes a first interface unit for receiving a SIP message from an originating terminal, a second interface unit for transmitting the SIP message to a called terminal, and the SIP message. And a control unit for determining whether the originating terminal is in a NAT environment and the originating terminal in a NAT and a first address assigned to the originating terminal in a private network included in the SIP message when the originating terminal is in a NAT environment. And a third interface unit for transmitting a second address assigned to the media relay unit, and requesting an allocation of an address for a media relay to the media relay unit for the first address and the second address.

In order to achieve the above object, a NAT-Traversal system according to an embodiment of the present invention is a terminal having a first address granted in a private network and a second address assigned in a NAT, the first address and the second address is described A SIP message processing apparatus for determining whether the terminal is in a NAT environment by analyzing the SIP message and the packet header of the terminal and requesting an address allocation for a media relay for the first address and the second address; Receives the first address and the second address from a SIP message processing device, allocates a media relay address to the first address and the second address according to the request, and assigns an address for the media relay to the first address and the second address; And a media relay device for relaying the media.

NAT-Traversal method using the IBCF / TrGW system in the IMS network according to an embodiment of the present invention to achieve the above object, the originating terminal belonging to the private network transmits a SIP message to the IBCF, the IBCF is the private network Requesting a media relay address allocation with a TrGW for a first address assigned to the originating terminal and a second address assigned to the originating terminal in NAT, and for the first address and the second address in the TrGW Assigning an address for the media relay and transmitting the media.

In order to achieve the above object, a NAT-Traversal method using an IBCF / TrGW system in an IMS network according to another embodiment of the present invention includes transmitting a REGISTER message to an IBCF by a UE belonging to a private network, wherein the IBCF transmits the REGISTER message. Storing all of the first address assigned to the terminal in the private network and the second address assigned to the terminal in the NAT, and transmitting to the CSCF, the first address assigned to the terminal in the private network and the NAT assigned to the terminal. Registering a second address with the CSCF; and when the SIP message is received by the terminal, sending the SIP message to the terminal by using the second address as the destination address.

Specific details of other embodiments are included in the detailed description and the drawings.

According to the SIP message processing apparatus according to the embodiment of the present invention as described above, and the interworking system and method in IMS, one or more of the following effects exist.

By solving NAT-Traversal problem in IMS network with devices that originally constitute IMS network, it is unnecessary to change hardware of terminal or existing network equipment, and it is effective to efficiently provide other network interworking service in IMS network. have.

In addition, according to the SIP message processing apparatus according to an embodiment of the present invention, the media relay and the SIP message transmission may proceed to all addresses that the originating terminal 110 may have. Thus, more stable SIP message origination and media relay are possible.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, “comprises” and / or “comprising” refers to the presence of one or more other components, steps, actions and / or devices. Or does not exclude additions.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a SIP message processing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the SIP message processing apparatus 210 according to an embodiment of the present invention may include a first interface unit 212, a second interface unit 214, a controller 216, and a third interface unit 218. It includes.

The first interface unit 212 receives a SIP message from the calling terminal 110. At this time, the SIP message received from the originating terminal 110 to the first interface unit 212 includes an address value of the originating terminal 110. For example, if the originating terminal 110 belongs to a private network, the originating terminal 110 is via a NAT. When the address in the private network of the originating terminal 110 has a private IP address and a private port value, NAT assigns a public IP address and a public port value to the originating terminal 110. At this time, the values of the private port and the public port may have the same value, or may have different values.

The second interface unit 214 transmits the SIP message received at the first interface unit 212 to the called terminal 310. At this time, the destination terminal 310 is described in Via of the SIP message by describing the first address given to the calling terminal 110 in the private network included in the SIP message and the second address assigned to the calling terminal 110 in the NAT. Send to

The controller 216 analyzes the SIP message to determine whether the originating terminal 110 is in a NAT environment. At this time, the controller 216 compares the terminal IP address described in the SDP of the SIP message with the source IP address described in the SIP message header, and determines that the value is different from the source terminal in the NAT environment.

When the controller 216 determines that the originating terminal 110 is in a NAT environment, the third interface unit 218 transmits the origination in the NAT and the first address assigned to the originating terminal 110 in the private network included in the SIP message. The second address assigned to the terminal 110 is transmitted to the media relay unit 240. At this time, the third interface unit 218 requests the media relay unit 240 to allocate an address for the media relay with respect to the first address and the second address.

According to the SIP message processing apparatus 210 according to an embodiment of the present invention, the media relay and the SIP message transmission may proceed to all addresses that the originating terminal 110 may have. Thus, more stable SIP message origination and media relay are possible.

Meanwhile, the SIP message processing apparatus 210 according to an embodiment of the present invention includes all devices capable of processing SIP messages. For example, the IBCF may be the SIP message processing device 210, but is not limited thereto. The SIP message processing device may be included in the IBCF or may be configured separately from the IBCF. 2 is a block diagram of a manganese interworking system in the IMS according to an embodiment of the present invention. In FIG. 2, the SIP message processing apparatus is an IBCF 210 and the media relay unit 240 is a transition gateway (TrGW) 240. However, as described above, the SIP message processing apparatus is not limited thereto. Of course, the device and the media relay can be replaced with all possible devices. Referring to FIG. 2, a network interworking system in an IMS includes an originating network 100, an IMS (IP Multimedia Subsystem) network 200, and a called network 300. Here, interworking with the network may mean interworking between the calling network 100 and the called network 300 based on the IMS network 200, but the IMS network 200 and the calling network 100, or the IMS network 200. ) And the interworking between the called network 300 may also be used. In the embodiment of the present invention described below, for convenience, the outgoing network 100 and the destination network 300 will be described as interworking based on the IMS network 200.

The originating network 100 is configured to include a source terminal 110 and NAT (Network Address Translation) 120 to translate the IP address for the originating terminal 110, the destination network 300 is the destination terminal 310 And a NAT 320 for translating the IP address for the destination terminal 310.

The originating terminal 110 and the terminating terminal 310 are assigned end-to-end hosts on the IP network and have been assigned a private IP address or a public IP address. If the public IP address is assigned, the address translation process may be unnecessary by the NAT 120 and 320.

NAT (120, 320) is located at the boundary of the source network 100 or the destination network 300 converts the source address information in the form of a private IP address included in the header of the packet to the source address information in the form of a public IP address. In addition, source address information in the form of public IP address is converted into source address information in the form of private IP. This source IP address information includes an IP address and a port. At this time, address translation is possible only for the network layer and the transport layer corresponding to layers 3 and 4 based on the Open System Interconnection (OSI) model.

Now, the IMS network 200 will be described. The IMS network 200 includes an IBCF 210, a Call Session Control Function (CSCF) 220, a Home Subscriber Server (HSS) 230, and a TrGW 240.

The IBCF 210 serves as a border controller between networks when interworking with IMS networks and handles security and interworking related issues when interworking with various networks. That is, the IBCF 210 is a system that performs IMS network interworking function. When the terminal in the NAT (120, 320) environment is connected, the IBCF 210 manages both the private IP address of the terminals (110, 310) and the public IP address given by the NAT (120, 320). That is, by managing both of the addresses that the terminals 110 and 310 may have, private IP addresses and public IP addresses, SIP messages may be transmitted to all addresses and ports available to the terminals 110 and 310. Make sure In addition, the IBCF 210 is connected to the TrGW 240, and provides the information of the terminal (110, 310) to the TrGW 240, at which time, the terminal (110, 310) in the NAT (120, 320) environment If present, provide both private and public IP addresses.

The CSCF 220 may perform basic functions for session initiation protocol (SIP) based multimedia session control such as subscriber registration, authentication, service triggering, routing, call control, and address handling. Here, the CSCF 220 has a subscriber registration function, and the CSCF 220 may be referred to as a subscriber registration device.

The CSCF 220 may include a Proxy-CSCF (P-CSCF), an Interrogating-CSCF (I-CSCF), and a Serving-CSCF (S-CSCF). .

P-CSCF is the first point that the terminal accesses the IMS. If a register request message (REGISTER) is transmitted from the terminal, the P-CSCF may deliver it to the I-CSCF. The P-CSCF may store the address of the S-CSCF allocated by the I-CSCF during the processing of the registration request message, and forward it to the S-CSCF when a session request message (INVITE) is received from the terminal.

The I-CSCF serves as a contact point for incoming calls to connect to subscriber stations in the entire network and as a point of contact with terminals of other network subscribers roaming in the network. The I-CSCF may obtain an address list of the S-CSCF available from the HSS 230 in the process of registering the user, that is, the subscriber, of the terminal, and may determine the S-CSCF to be in charge of actual registration by referring to this.

The S-CSCF may register a subscriber with the HSS 230 when the registration request message is received from the I-CSCF, and obtain a subscriber profile from the HSS 230. The S-CSCF may identify the type of service to be provided to the terminal by using the subscriber profile and perform triggering on an IMS enabler, that is, an AS (Application Server), that will support the identified service. In addition, the S-CSCF may obtain and manage an authentication vector (AV) from the HSS 230. In addition, the S-CSCF may perform subscriber authentication using an authentication vector.

The HSS 230 is a subscriber's master database, which stores and manages subscriber profile, authentication, and location related data, and provides information required by the CSCF 220. In addition, the HSS 230 may generate an authentication vector required for subscriber authentication, and may include a function of a home location register (HLR).

The TrGW 240 relays real traffic data (RTP / RTCP, MSRP) for the session established by the IMS network SIP. The TrGW 240 receives the information of the terminals 110 and 310 from the IBCF 210, for example, the IP addresses of the calling terminal 110 and the called terminal 310, and thus the calling terminal 110 and the called terminal 310. Send and receive media data between At this time, when both the private IP address and the public IP address of the originating terminal 110 and / or destination terminal 310 from the IBCF 210, when transmitting and receiving media data to each terminal (110, 310) Media relay processing is possible with both the private IP address and the public IP address.

3 is a call flow diagram for a REGISTER message in a method for interworking between networks in an IMS according to an embodiment of the present invention.

Referring to FIGS. 2 and 3, the terminals 110 and 310 of FIG. 3 include the calling terminal 110 and the called terminal 310 of FIG. 2. That is, it includes all the terminals belonging to the private network.

The terminals 110 and 310 transmit a REGISTER message to the IBCF 210 (S410).

At this time, when the terminal (110, 310) belongs to a private network, the terminal (110, 310) via the NAT (120, 320). When the address in the private network of the terminal (110, 310) has a private IP address and private port value, NAT (120, 320) gives the terminal 110, 310 a public IP address and a public port value. At this time, the values of the private port and the public port may have the same value, or may have different values.

The IBCF 210 analyzes the transmitted REGISTER message, which includes the address (A: private IP address and private port) of the contact header of the REGISTER message and the source address (A ': public IP address and public port) of the packet that sent the REGISTER message. If the values are different from each other, it is recognized as a terminal (110, 310) in the NAT (120, 320) environment. If the terminal 110, 310 is recognized as being in the NAT (120, 320) environment, the IBCF 210, both the address A and the address A 'of the terminal (110, 310) in the user-part of the contact of the REGISTER message List it. In other words, enter both the private IP address, private port and public IP address, and public port in the contact of the register message.

The IBCF 210 reflecting the address A and the address A 'in the register message transmits the register message to the CSCF 220 (S420).

The REGISTER message is first transmitted to the P-CSCF of the CSCF 220. The P-CSCF transmits the REGISTER message to the I-CSCF, and the I-CSCF receives the address of the HSS 230 from the server locator function (SLF). Acquire and transmit a User Authorization Request (UAR) message to the HSS 230 using the obtained address. The HSS 230 selects an appropriate S-CSCF by referring to the UAR message transmitted from the I-CSCF, and sends a User Authorization Answer (UAA) message including information on the selected S-CSCF to the I-CSCF. Send to. The I-CSCF may set an S-CSCF to process a registration request of the terminals 110 and 310 through the UAA message, and transmit a registration request message to the set S-CSCF.

Here, since both the address A and the address A 'are reflected in the user-part of the contact of the REGISTER message, the address A and the address A' are also included in the information registered in the S-CSCF.

In this regard, when the S-CSCF transmits a 200 OK message to the P-CSCF, and the P-CSCF transmits the 200 OK message to the IBCF 210 (S430), the IBCF 210 returns to the terminals 110 and 310. The 200 OK message is transmitted (S440).

4 is a call flow diagram for an INVITE message in a method for interworking networks between IMSs according to an embodiment of the present invention.

2 and 4, the calling terminal 110 transmits an INVITE message to the IBCF 210 (S510).

At this time, when address A in the private network of the calling terminal 110 has a private IP address and a private port value, the calling terminal 110 writes address A (private IP address, private port) in the Via header of the INVITE message. And use the rport parameter.

At this time, if the originating terminal 110 belongs to a private network, the originating terminal 110 via the NAT (120). NAT 120 gives an address A '(a public IP address, a public port) to the originating terminal (110). At this time, the values of the private port and the public port may have the same value, or may have different values.

The IBCF 210 analyzes the transmitted INVITE message to determine the terminal IP address (address A) described in the Session Description Protocol (SDP) of the INVITE message, and the source address (A ': public IP address and public port) of the packet that sent the INVITE message. ), And if the value is different from each other, it is recognized as the originating terminal 110 in the NAT 120 environment. If the originating terminal 110 recognizes that it is in the NAT 120 environment, the IBCF 210 first requests the TrGW 240 to allocate a media relay address that accepts both of these addresses A and A '. . The TrGW 240 notifies the IBCF 210 by allocating a destination address T1 for the originating terminal 110 in response to the request, and then relays the addresses A and A 'of the two originating terminals 110. Be prepared. The IBCF 210 reflects the relay address T1 for the calling terminal 110 allocated by the TrGW 240 to the m / c line in the SDP of the INVITE, and then routes the response message to the calling terminal 110. In the Via header of the INVITE message, add address A '(a public IP address, a public port). For example, the public IP address is entered as the value of the Received parameter, and the value of the public port is reflected as the value of the rport parameter. Then, both the address A and the address A 'are written in the Via header of the INVITE message.

In addition, IBCF 210 further describes its address P in the top Via header.

The IBCF 210 responds to the INVITE message by transmitting a 100 Trying message to the originating terminal 110 (S520).

The IBCF 210 transmits the INVITE message reflecting the address A and the address A 'to the called terminal 310 (S530). More specifically, the IBCF 210 transmits the INVITE message reflecting the address A and the address A 'to the calling CSCF, and the calling CSCF sends the INVITE message to the called CSCF. Then, the called CSCF transmits the INVITE message to the called IBCF, and the called IBCF sends the INVITE to the called terminal 310. In response to the INVITE message, the called terminal 310 responds by transmitting a 100 Trying message to the IBCF 210 (S540). In addition, the destination terminal 310 transmits a 180 ringing message to the IBCF 210 (S550). The IBCF 210 receives the 180 ringing message and transmits it to the calling terminal 110 (S560).

The terminating terminal 310 transmits a 200 OK message to the IBCF 210 (S570). The terminating terminal 310 sends the IBCF 210 to the IBCF 210 while preserving the Via header in which the address A, the address A 'and the address P are written. send.

When the 200 OK message is received by the IBCF 210, the IBCF 210 requests the TrGW 240 to allocate a media relay address that accepts the address B of the called terminal. The TrGW 240 allocates a destination address T2 for the destination terminal 310 to the IBCF 210 in response to the request, and then prepares a relay for the address B of the destination terminal 310. The IBCF 210 reflects the relay address T2 for the originating terminal 110 allocated by the TrGW 240 to the m / c line in the SDP of 200 OK, and then deletes its address P from the Via header. Then, the value of address A '(a public IP address, a public port) described as a Received parameter and a rport parameter in the Via header is set as a destination address and transmitted to the calling terminal 110.

Then, the 200 OK message is transmitted to the NAT 120, and passes through the NAT 120 to the originating terminal 110.

5 is a block diagram illustrating a method for interworking between networks in an IMS according to an embodiment of the present invention.

2 and 5, the calling terminal 110 transmits a SIP message to the IBCF 210 (S610).

At this time, if the originating terminal 110 belongs to a private network, the originating terminal 110 via the NAT (120). When the calling terminal 110 has an address A (first private IP address, first private port), the NAT 120 transmits an address A '(first public IP address, first public port) to the calling terminal 110. To give. At this time, the private port and the public port may have the same value, but may have different values.

The IBCF 210 analyzes the transmitted SIP message and compares the terminal IP address (address A) described in the SDP of the SIP message with the source IP address (address A ') described in the SIP message header (S620).

If the values of the two compared addresses are different, the IBCF 210 makes a media allocation request to the TrGW 240 to accommodate both of the two addresses (address A, address A ') (S630).

The TrGW 240 allocates the media relay address T1 (first address, first port) to the calling terminal 110 and prepares for media transmission to both address A and address A '(S640). Having the TrGW 240 proceed with media transmission for both addresses A and A 'is a media transmission for all addresses that the originating terminal 110 may have since the existence of the NAT 120 is uncertain. To proceed.

Meanwhile, the IBCF 210 transmits the SIP message to the called terminal 310 via the CSCF 220 (S650).

In this case, when the called terminal 310 is also in the NAT 320 environment, information stored in the registration process of the terminal is utilized. That is, as described above, when the UE in the NAT 320 environment is registered in the private network, the address B (second private IP address, second private port) and address B '(first address) in the user-part of the contact of the REGISTER message are registered. 2 public IP address, second public port). Therefore, the address B '(second public IP address, second public port) stored in the registration process is set as a destination address and transmitted to the called terminal 310.

Then, the SIP message is transmitted to the NAT 320, and passes through the NAT 320 to the destination terminal 310.

The called terminal 310 transmits a 200 OK message to the IBCF 210 (S662), and the IBCF 210 transmits a 200 OK message to the calling terminal 110 (S664).

At this time, the IBCF 210 analyzes the 200 OK message received from the destination terminal 310 to determine the terminal IP address (address B) described in the Session Description Protocol (SDP) of the 200 OK message, and the source described in the 200 OK message header. Compare the IP address (address B ') (S670).

If the values of the two compared addresses are different, the IBCF 210 makes a media allocation request to the TrGW 240 to accommodate both of the two addresses (address B and address B ') (S680).

The TrGW 240 allocates the media relay address T2 (second address, second port) to the destination terminal 310 and prepares to proceed with media transmission for both address B and address B '(S690).

Referring to FIG. 5, when a session is connected between the calling terminal 110 and the called terminal 310, a media relay proceeds as follows.

That is, address A at originating terminal 110, address A 'converted at NAT 120, address T1 assigned at destination terminal 310 at TrGW 240, and destination terminal 310 at TrGW 240; The media relay may proceed in the order of the allocated address T2, the address B 'converted in the NAT 320, and the address B in the called terminal 310.

That is, the media transmission process may be transmitted from the calling terminal 110 to the called terminal 310 via the TrGW 240 in the same order as described above. In addition, the media transmitted by the called terminal 310 may be transmitted to the calling terminal 110 through the reverse process.

According to the SIP message processing apparatus in the IMS network, the NAT-Traversal system and method in the IMS according to the embodiments of the present invention, the terminal or the existing by solving the NAT-Traversal problem in the IMS network with devices inherently equipped It is not necessary to change the hardware of the network equipment, it is possible to efficiently provide other network interworking services in the IMS network.

In addition, since the media transmission and SIP message delivery to all addresses assigned to the terminals belonging to the private network, it is possible to solve the NAT-Traversal problem more effectively.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. You will understand that. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1 is a block diagram of a SIP message processing apparatus according to an embodiment of the present invention.

2 is a block diagram of a manganese interworking system in the IMS according to an embodiment of the present invention.

3 is a call flow diagram for a REGISTER message in a method for interworking between networks in an IMS according to a first embodiment of the present invention.

4 is a call flow diagram for an INVITE message in a method for interworking between networks in an IMS according to a second embodiment of the present invention.

5 is a block diagram for explaining a method of interworking between networks in an IMS according to a third embodiment of the present invention.

<Explanation of symbols on main parts of the drawings>

100: source network 200: IMS network

210: IBCF 220: CSCF

230: HSS 240: TrGW

300: incoming network 110, 310: terminal

Claims (16)

A first interface unit receiving a SIP message from an originating terminal; A second interface unit for transmitting the SIP message to a called terminal; A controller which analyzes the SIP message and determines whether the calling terminal is in a NAT environment; And When the originating terminal is in a NAT environment, a first address assigned to the originating terminal and a second address assigned to the originating terminal in NAT are transmitted to a media relay unit in a private network included in the SIP message, and the first address is transmitted. And a third interface unit for requesting an allocation of an address for a media relay to the media relay unit for the second address. The method of claim 1, The control unit compares the terminal IP address described in the SDP of the SIP message with the source IP address described in the SIP message header, and if the value is different from each other SIP message processing apparatus to determine the originating terminal in the NAT environment. The method of claim 1, And the second interface unit writes the first address and the second address to Via of the SIP message and sends the same to the called terminal. delete The method of claim 1, And the first address and the second address each include an IP address and port information. A terminal having a first address assigned in a private network and a second address assigned in a NAT; The SIP message and the corresponding packet header of the terminal in which the first address and the second address are described are analyzed to determine whether the terminal is in a NAT environment, and an address for a media relay for the first address and the second address. A SIP message processing apparatus requesting an assignment; And The first address and the second address are received from the SIP message processing device, and the media address is allocated to the first address and the second address in response to the request, thereby the first address and the second address. A NAT-Traversal system comprising a media relay device for relaying media against. The method of claim 6, The SIP message processing apparatus compares the terminal IP address described in the SDP of the SIP message with the source IP address described in the SIP message header, and if the values are different from each other, the NAT-Traversal system determines the originating terminal in the NAT environment. . delete The method of claim 6, The SIP message processing apparatus, upon receiving a REGISTER message, includes both the first address and the second address in the REGISTER message and transmits it to the subscriber registration apparatus. The method of claim 9, The first address and the second address is NAT-Traversal system described in the user-part of the contact in the register message. The method of claim 6, The SIP message processing apparatus, upon receiving a request message or a response message, writes the first address and the second address in Via of the request message or response message, and transmits them to the called terminal. The method of claim 6, And the first address and the second address respectively include IP address and port information. The method of claim 6, The SIP message processing device is an IBCF, and the media relay device is a TrGW NAT-Traversal system. Transmitting, by the originating terminal belonging to the private network, the SIP message to the IBCF; Requesting, by the IBCF, a media relay address allocation to TrGW for a first address assigned to the originating terminal in the private network and a second address assigned to the originating terminal in NAT; And And assigning an address for a media relay for the first address and the second address and transmitting media in the TrGW. Transmitting, by the UE belonging to the private network, a REGISTER message to the IBCF; The IBCF including both a first address assigned to the terminal in a private network and a second address assigned to the terminal in a NAT in the REGISTER message and transmitting the same to the CSCF; Registering a first address assigned to the terminal in a private network and a second address assigned to the terminal in a NAT with a CSCF; And When the SIP message is received by the terminal, the SIP message processing apparatus comprising the step of sending a SIP message to the terminal using the second address as the destination address NAT-Traversal method in IMS. delete

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