KR101766666B1 - Session initiation protocol based network system for preventing infinite forwarding and method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for transmitting an INVITE message received from a calling terminal in a Session Initiation Protocol (SIP) based network to a called terminal through a device operating in a B2BUA (Back to Back User Agent) mode, Based network system for preventing infinite looping by preventing infinite forwarding of an invite message by changing the head value of the SIP message to operate in a proxy mode, and a method thereof.

Description

Technical Field [0001] The present invention relates to a session establishment protocol based network system for preventing infinite looping,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a session initiation protocol (SIP) -based network system, and more particularly, to a network system based on a Session Initiation Protocol (SIP) ) Mode, the device changes the header value of the INVITE message to operate in a proxy mode, thereby preventing infinite looping prevention of the INVITE message. Based network system and a method thereof.

In a voice call communication service in a general mobile communication network and a public telephone network, only a simple information is exchanged between users, while a data call service (for example, a voice call service in a wired / wireless Internet network (IP network or packet data network) Conference, telephone, voicemail, event notification, instant message, etc.), various kinds of data can be transmitted while exchanging various information between users.

The above data communication service in the wired / wireless Internet network is based on SIP. SIP is designed to be used regardless of the type of session to be created, and can be used for session control of various types of multimedia services as well as Internet telephony.

Typically, SIP-based services include VoIP (Voice Over Internet Protocol) network and IMS (IP Multimedia Subsystem) network.

For example, FIG. 1 illustrates call processing in a SIP-based VOIP system.

1, the dialing number of the calling terminal 10 is Alice and the dialing number of the calling terminal 40 is Bob. At this time, the called terminal is subscribed to an outgoing call display service (call keeper service) and an unconditional call forwarding service, and the call forwarding number is set as a zone (John).

When the Alice of the calling terminal 10 dials Bob of the called terminal 40 under the above conditions, the calling terminal 10 transmits an INBI for the call connection with the called terminal 40, Message to the P-CSCF 21, the S-CSCF 22, and the I-CSCF 23 of the home network 20 in the order of (1), (2) . CSCF 33 and S-CSCF 32 of the visited network 30 and the P-CSCF 31 to the called terminal 40. In this case,

At this time, the S-CSCF (32) of the visited network (30) can confirm whether the called terminal (40) to receive the invite message joins the service. If the destination terminal 40 is subscribed to a predetermined service, the S-CSCF 32 forwards the Invite message to the corresponding management apparatus and transmits the service session before delivering the Invite message to the P-CSCF 31.

Since the call receiving terminal 40 is subscribed to the outgoing call display service from the above setting conditions, the SIP Invite message is delivered to the absence management device 34 as in (6).

Since Bob of the receiving terminal 40 is subscribed to the unconditional call forwarding service, the SIP invite message is delivered to the call forwarding management device 35 as in (8).

Since the absence management device 34 and the call forwarding management device 35 operate in a B2BUA (Back-to-Back User Agent) mode for separating the call of the calling terminal and the call of the called terminal, (40), it is regarded as a new message and is sent out. Therefore, the absence management apparatus 34 and the call forwarding management apparatus 35 set the forward header value of the invite message to be routed to the S-CSCF 32 as an initial value and transmit the forward header value.

The forward header referred to here is a forwarding field included in the header in the SIP message specification (RFC 3261), and is set to an initial value when a new invite message is generated, and then passes through one node of the home network 20 or the visited network 30 Each time the forward header value is minus-counted sequentially. When the forward header value reaches 0 at the time of continuing the negative counting, an error message is generated, and the byte message associated with the dialog is not transmitted any more, thereby preventing infinite transmission of the dialogue related byte message.

1, the initial value of the forward header value is set to 70, and the P-CSCF 21, the S-CSCF 22, the I-CSCF 23 of the home network 20, the visited Forward header values are sequentially minus-counted when an invite message is delivered to the I-CSCF 33, the S-CSCF 32 and the P-CSCF0 31 of the network 30, and the out-of-office management The device 34 and the call transferring management device 35 set the forward header value back to the initial value of 70 and deliver it.

However, if Bob of the receiving terminal 40 sets the call forwarding number as the own number, infinite looping phenomenon occurs as follows.

That is, when Alice of the calling terminal 10 requests the Bob of the called terminal 40, the S-CSCF 32 of the visited network 30 sends a call to the Bob of the called terminal 40 Bob is subscribed to the outgoing call display service and the unconditional call forwarding service, the SIP Invite message is delivered to the absence management device 34 and the call forwarding management device 35 as described in (6) and (8) (7), (9)) from the absence management apparatus 34 and the call transferring management apparatus 35 in response to the new invite message.

At this time, since the call forwarding number of Bob, which is the destination terminal 40, is the own terminal, the call forwarding management device 35 transfers the invite message set as the Bob Bob to the S-CSCF 32 .

Then, the S-CSCF 32 analyzes the incoming message received from the call forwarding management device 35 again. Since Bob, which is the incoming caller of the incoming message, is subscribed to the outgoing call display service, To the absence management device 34 as shown in FIG.

According to this, (6) - (7) - (8) - (9) - (6) - (7) - (8) - (9) - (6) ... The infinite looping phenomenon occurs repeatedly. That is, the absence management device 34 and the call forwarding management device 35 set the forward header value to the initial value and transmit it, so that the looping phenomenon occurs infinitely and a problem may occur in the SIP-based network.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a method and system for transmitting an INVITE message received from a calling terminal in a SIP-based network to a called terminal through a device operating in a B2BUA The present invention provides a SIP-based network system and a method thereof, which prevent a device from infinite forwarding by changing a header value of an INVITE message to operate in a proxy mode.

To this end, according to a first aspect of the present invention, there is provided a network system for infinite looping prevention according to the present invention, the network system for endless looping prevention comprising: a receiving terminal for receiving a message including a call connection request from a calling terminal according to a call connection request to a called terminal, A call service control device for confirming whether or not the terminal is subscribed to a service; And an application service apparatus for counting a forward header value of the message upon receiving the message from the call service control apparatus and transmitting the message to the call service control apparatus.

According to a second aspect of the present invention, there is provided an application service apparatus of the present invention, which interfaces with a call service control apparatus that handles call connection between a calling terminal and a called terminal, receives a message from the call service control apparatus, And transmits the message to the call service control apparatus.

According to a third aspect of the present invention, there is provided an infinite looping prevention method comprising the steps of: (a) receiving a call connection request from a calling terminal to a called terminal, the call service controlling device processing a call connection between the calling terminal and the called terminal The method comprising: receiving a message; (b) confirming whether or not the call service control apparatus joins the service to the called terminal receiving the message; (c) if the called terminal is subscribed to a predetermined service, the call service control apparatus transmits the message to an application service apparatus providing the service; (d) counting a forward header value of a message received from the call service control apparatus by the application service apparatus; (e) transmitting, by the application service apparatus, a message having a counted forward header value to the call service control apparatus.

According to a fourth aspect of the present invention, there is provided an infinite looping prevention method comprising the steps of: (a) receiving a call connection request from a calling terminal to a called terminal, the call service controlling device processing a call connection between the calling terminal and the called terminal The method comprising: receiving a message; (b) confirming that the call service control apparatus is in the absence of the called terminal; (c) transmitting the message to the absence management apparatus, wherein the call service control apparatus provides a missed service; (d) counting a forward header value of a message received from the call service control apparatus by the absence management apparatus and transmitting the message to the call service control apparatus; (e) confirming that the call service control apparatus joins the call forwarding service of the called terminal; (f) transmitting the message to the call transferring management apparatus in which the call service control apparatus provides the call transfer service; (g) counting a forward header value of a message received from the call switching management apparatus from the call service control apparatus and transmitting the message to the call service control apparatus.

According to a fifth aspect of the present invention, there is provided an infinite looping prevention method in an application service apparatus of an embodiment of the present invention, comprising: a step in which an application service apparatus receives a message including a call connection request from a call service control apparatus to a called terminal of a calling terminal ; Counting a forward header value of a message received from the call service control apparatus by the application service apparatus; And transmitting the message having the forward header value counted by the application service apparatus to the call service control apparatus.

According to the present invention, when transmitting an invite message from an application service apparatus operating in a Back-to-Back User Agent (B2BUA) mode in a SIP-based network, the header value of the invite message is counted It is possible to prevent the invite message from being infinitely forwarded. This provides the effect of solving the resource shortage of the communication channel because it can disconnect or reallocate the call resources necessary for the allocation of infinite looping.

In addition, the counting operation in the application service apparatus can be applied to all the invite messages received from the call service control apparatus. However, if a service of call forward switching type is requested by using the B2BUA mode and the proxy mode as needed, Mode, and thus the existing infrastructure can be utilized flexibly.

In addition, when the header value of the invite message becomes a specific value other than 0, the looping is terminated, and the number of times of the infinite looping is further shortened, so that the call resource allocated to the looping can be rapidly reallocated .

1 illustrates endless looping in a network system based on a session establishment protocol according to the prior art;
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a session establishment protocol-based network system for preventing infinite looping according to an embodiment of the present invention.
3 is a diagram illustrating a call flow in a case where an incoming call is its own terminal in a network system based on a session establishment protocol according to an embodiment of the present invention;
4 is a flowchart illustrating an infinite looping prevention method in a network system based on a session establishment protocol according to an embodiment of the present invention.
5 is a detailed flow diagram illustrating an infinite looping prevention method when an incoming call is a self-number;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description. Before describing the present invention in detail, the same components are denoted by the same reference symbols as possible even if they are displayed on different drawings. In the case where it is judged that the gist of the present invention may be blurred to a known configuration, do.

Before starting the detailed description of the present invention, the operation of the application service apparatus according to the present invention will be described. The application service apparatus operates in a proxy mode or a B2BUA mode according to a service.

The proxy mode is responsible for processing the response to the invite message received from another node or routing the message to the next device. In this proxy mode, the forward header value of the invite message is sequentially counted and transmitted based on the previous value.

The B2BUA mode separates the calling terminal and the called terminal so as to process and manage the respective operations. Unlike the proxy mode in which the call is routed only, the received invite message is modified or, as another form, . The device operating in the B2BUA mode transmits the invite message received from the call service control device to the destination terminal so as to have a separate channel from the calling terminal processing operation. As described above, since the B2BUA mode processes the received message and the message to be transmitted to the destination terminal separately, the forward header value of the INVITE message is set back to the initial value regardless of the previous value and transmitted .

Here, the forward header value of the INVITE message means a value for preventing the infinite looping by limiting the number of forwarding times of the INVITE message.

FIG. 2 is a block diagram of a network system based on a session establishment protocol for preventing infinite looping according to an embodiment of the present invention. Referring to FIG.

The SIP-based network system according to the embodiment of the present invention includes a call service control apparatus 200 for controlling a call between a calling terminal 100 and a called terminal 400, an application service apparatus 200 providing an additional service based on SIP 300).

The calling terminal 100 and the called terminal 400 may be implemented as a multi-band mobile communication terminal capable of connecting to various radio access networks, such as a cellular phone, a cellular phone, a smart phone, or the like.

In particular, the calling terminal 100 generates and transmits a SIP Invite message including a call connection request.

The terminating terminal 400 transmits a response signal to the SIP INVITE message received from the calling terminal 100.

The call service control apparatus 200 is a device for routing messages between the calling terminal 100, the called terminal 400 and the application service apparatus 300, And transmits the invite message received from the application service apparatus 300 to the call receiving terminal 400. [

In addition, the call service control apparatus 200 can confirm whether or not the called terminal 400 receiving the invite message receives a service when the invite message is received from the calling terminal 100. In this case, if the called terminal 400 is subscribed to a predetermined service, the call is invited to the application service apparatus 300 and routed to receive the corresponding service.

The call service control apparatus 200 may include a call session control function (CSCF). In addition to the functions described above, the CSCF processes subscriber registration, authentication, billing, service-specific triggering, routing to the corresponding application service device, location inquiry of the destination terminal 400, Session setup, adjustment, and management. The CSCF may be interworked with an HSS (Home Subscriber Server) in which the subscriber profile information, authentication and location related data are stored.

Specifically, the CSCF is an infrastructure system that performs basic functions for SIP-based multimedia session control. As shown in FIG. 3, the CSCF includes a P-CSCF (Proxy-CSCF) 210, an S- : 220), and I-CSCF (Interrogating-CSCF: 230).

The P-CSCF 210 serves as a proxy between the user terminal and the I-CSCF 230 at the time of SIP registration, which is the first point of access to the user terminal in the IMS network. Also, at the time of setting up a SIP call, it serves as a proxy between the user terminal and the S-CSCF (220), compresses or releases the SIP message, and generates a billing record.

The I-CSCF 230 is located at the boundary of the service provider domain and searches for the S-CSCF in which the called terminal 400 is registered as the first point to which the service provider accesses, Roaming) S-CSCF of a user is searched. In addition, it performs a firewall (THIG: Topology Hiding Inter-network Gateway) function to prevent the configuration, capacity, and topology information of the network from being exposed to the outside. In this embodiment, the I-CSCF grasps the network to which the destination terminal 400 belongs from the interworked HSS, and transmits the SIP message including the call connection request to the S-CSCF in which the destination terminal 400 is registered.

The S-CSCF 220 registers with the home subscriber server (HSS) that it is a device for controlling the session of the using terminal, and obtains and stores the subscriber information of the user terminal. And performs session control and state management for the registered use terminal. In addition, in order to provide various services, a SIP request and response message is transmitted to a BGCF (Breakout Gateway Control Function) in order to interwork with other application service devices or to route a message received to the S-CSCF 220. In particular, the S-CSCF 220 according to the embodiment of the present invention grasps the information of the called terminal 400 based on the received SIP invite message and transmits the SIP call message including the call connection request received from the calling terminal 100 And transmits the SIP Invite message to the called terminal 400 via the P-CSCF 210 in the network.

The application service apparatus 300 is also called an application server (AS) in the SIP-based network and performs various additional services. The called terminal 400 performs the service to which the called terminal 400 belongs.

In addition, the application service apparatus 300 interfaces with the S-CSCF 220 of the call service control apparatus 200 using the SIP to distribute the supplementary service to the terminal subscribing to the predetermined service. Examples of ancillary services include, but are not limited to, calling number related services, call hold, call hold, push-to-talk, call transfer, call forwarding, call blocking services, , A conference call service, a voice mailbox, a character and voice conversion, a location based service, an SMS (Short Message Service), a MMS (Multi Message Service), a presence information and an instant messaging service.

In particular, the application service apparatus 300 performs individual processing and management of operations of the calling terminal 100 and the called terminal 400 in the SIP through the B2BUA mode operation, Counts the forward header value of the SIP invite message and transmits it. To this end, the application service apparatus 300 may change from the B2BUA mode to the proxy mode. Therefore, even if message looping occurs between the application service apparatus 300 and the call service control apparatus 200, infinite looping can be prevented by counting forward header values.

The counting in the application service apparatus 300 may be a negative counting method in which the forward header value is subtracted, but a positive counting method in which the forwarding header value is increased or decreased is also possible.

For example, call processing in the case where the call forwarding number of the called terminal is set as the own number will be described with reference to FIG.

If the same conditions are applied so as to be compared with the conventional example, the calling terminal is Alice, the Bob of the called terminal is subscribed to the outgoing call display service (call keeper service) and the unconditional call forwarding service, The call forwarding number of the called terminal becomes Bob.

3, the application service apparatus 300 is divided into a first application service apparatus 310 and a second application service apparatus 320 according to the type of supplementary service. For the sake of understanding, The second application service apparatus 320 is an absence management apparatus for providing a telephone display service, and the second application service apparatus 320 is a call transfer management apparatus for providing an unconditional call diversion service.

The call service control apparatus 200 performs call processing by dividing into P-CSCF 210, S-CSCF 220 and I-CSCF 230.

Under the above conditions, when Alice of the calling terminal 10 requests the Bob of the receiving terminal 40 to dial, the calling terminal 100 generates an invite message for an outgoing call connection, To the control device (200).

The call service control apparatus 200 transmits the invite message received from the calling terminal 100 sequentially through the S-CSCF 220 and the I-CSCF 230 through the P-CSCF 210. At this time, The forward header value of the message is counted minus one by one from the previous value as shown in (2) and transmitted.

At this time, since the Bob of the called terminal 400 is subscribed to the outgoing call display service in the absence of the called terminal 400, the S-CSCF 220 transmits an invite message to the first application service device 310 And receives the invite message from the first application service apparatus 310 in response to (4). At this time, the forward header value 67 of the invite message received from the application service apparatus 310 is not set to the initial value, but is negative-counted in the forward header value 68 of the invite message.

Since the Bob of the receiver terminal 400 is subscribed to the unconditional call forwarding service, the S-CSCF 110 delivers the Invite message to the second application service apparatus 320 in the direction of arrow 5 . At this time, since the call forwarding number of Bob as the receiving terminal 400 is itself, the second application service apparatus 320 transmits an invite message to Bob Bob to the S-CSCF 110 as shown in (6) And the S-CSCF 110 receives it.

In the S-CSCF 110, Bob, which is an incoming call message received from the second application service apparatus 320, is subscribed to the outgoing call display service. Therefore, And transmits the call to the controller 310 to repeat the above process.

That is, (3) - (4) - (5) - (6) - (3) - (4) - (5) - (6) - (3) A looping phenomenon occurs repeatedly. However, if the forward header value of the invite message transmitted from the first application service apparatus 310 and the second application service apparatus 320 to the called terminal 400 is 68-67-66-65-64-63-62- 61-60- ... The forward header value becomes 0 at any moment even if looping occurs, and the forwarding of the message is terminated. Thus, infinite looping can be prevented.

Hereinafter, a call flow for preventing infinite looping in a system having the above configuration will be described in detail.

4 is a flowchart illustrating an infinite looping prevention method in a network system based on a session establishment protocol according to an embodiment of the present invention.

When the calling terminal 100 requests the called terminal 400 for dialing, the calling terminal 100 generates an invite message for making a call connection with the called terminal 400 and transmits the invite message to the call service control device 200 (S101).

For example, the IP address of the calling terminal 100, the called terminal information, the SDP (Session Description Protocol) information of the calling terminal 100, and the like may be included in the inbox message transmitted by the calling terminal 100. Here, the IP address of the calling terminal 100 means an address value for identifying the calling terminal 100 when performing TCP / IP based communication.

The call service control apparatus 200 on the home network receiving the invite message routes to the P-CSCF 210, the S-CSCF 220 and the I-CSCF 230 (S102, S103) , The I-CSCF 230 confirms the subscriber location of the destination terminal 400 to be the destination of the invite message received from the S-CSCF 220 and transmits the visited network address of the visited network 400 to which the destination terminal 400 is located And transmits the invite message to the I-CSCF 230 (S104, S105).

The I-CSCF 230 of the visit network transmits the received invite message to the S-CSCF 220 in step S 106 and the S-CSCF 220 receiving the invite message transmits the invite message to the S- Service and subscribes to the supplementary service, it triggers the application service apparatus 300 additionally (S107).

Thereafter, when the S-CSCF 220 transmits an invite message to the application service apparatus 300 (S108), the application service apparatus 300 counts the forward header value of the received invite message from the previous value And then transmits it to the S-CSCF 220 (S109, S110). At this time, the counting may use a negative counting method for subtracting the forward header value of the byte message or a positive counting method for increasing or decreasing the forward header value.

Then, the S-CSCF 220 transmits the invite message received from the application service apparatus 300 to the P-CSCF 210 of the visit network (S111), and the P- And transmits a call message to the called terminal 400 to establish a call connection between the calling terminal 100 and the called terminal 400 (S112).

4, the calling terminal 100 and the terminating terminal 400 are located in different networks. When the calling terminal 100 and the terminating terminal 400 are located in the same network, All call processing can be done in the home network.

For example, an infinite looping prevention method in a case where a calling terminal and a called terminal are located in the same network and a called terminal sets a call forwarding as a self-number will be described.

Referring to FIG. 5, when the calling terminal 100 requests dialing to the called terminal 400 that is subscribed to the outgoing call display service and the call forwarding service, the calling terminal 100 first transmits a message for call connection with the called terminal That is, the SIP-based invite message is generated and transmitted to the call service control apparatus 200 (S201).

At this time, the calling terminal 100 sets the forward header value of the invite message to an initial value of 70 and transmits it to the call service control apparatus 200 (S201).

The P-CSCF 210 then counts the forward header value of the invite message as negative 69 and routes it to the S-CSCF 220 (S202), and the S-CSCF (220) 220 confirms which service the calling terminal 400 is subscribed to before being routed to the I-CSCF 230 (S203).

For example, if the called terminal is subscribed to an outgoing call display service (call-keeper service) and an unconditional call forwarding service, the S-CSCF 220 confirms this and performs triggering with the in- S203). Here, it is assumed that the absence management apparatus is the first application service apparatus 310.

At the same time as the trigger, the S-CSCF 220 of the home network counts the forward header value of the corresponding INVITE message as negative 68 and routes it to the first application service device 310 (S204) The service device 310 negatively counts the forward header value of the invite message received from the S-CSCF 220 to 67, and transmits it to the S-CSCF 220 (S205).

Thereafter, the S-CSCF 220 delivers the invite message to the second application service apparatus 320, which is the call transfer management apparatus (S206, S207). Upon delivery, the S-CSCF 220 passes the forward header value of the INVITE message with a negative count of the previous value of 68 to 67.

Then, the second application service apparatus 320, like the first application service apparatus 310, counts the forward header value of the invite message received from the S-CSCF 220 from the previous value which is not the initial value 70, CSCF 220 in step S208, and sets the message to Bob in step S208.

Since Bob, which is an incoming call of the invite message received from the second application service apparatus 320, is subscribed to the outgoing call display service, the S-CSCF 220 returns to the first application service apparatus 310 ). Thereafter, steps S204 to S208 are performed in the same manner.

If the terminal that subscribed to the call forwarding service has set up the call forwarding by its own number, it transmits an invite message between the first application service apparatus 310 and the second application service apparatus 320 via the S-CSCF 220 In the present invention, the forward header value of the INVITE message is sequentially minus-counted each time it passes through the S-CSCF 220 and the first and second application service devices 330 and 340, Looping is performed only until the set specific value (e.g., 0) (S209).

When the forward header value becomes the predetermined value, the '483 Too Many Hops' error message is generated, and the call transmission is terminated without transferring the byte message (S210).

This prevents infinite looping.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. For example, the counting operation in the application service apparatus may be applied to all invite messages received from the call service control apparatus, but in normal operation, the apparatus operates in the B2BUA mode for individually processing the operations of the calling terminal and the called terminal, When the request for the diversion service is received, the mode may be changed to a proxy operation in which the forward header value of the SIP invite message is counted.

In addition, when the application service apparatus or the call service control apparatus operates in the proxy mode, the forward header value of the SIP invite message may be counted in a negative form, but the forward header value may be incremented or decremented in a positive form .

Accordingly, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

In the conventional SIP-based network, a byte message is infinitely looped in providing a service of a call switching type, and a problem occurs in the network. However, the present invention is applicable to an application service apparatus operating in a Back to Back User Agent (B2BUA) By preventing the infinite message from being infinitely forwarded by changing the header value of the INVITE message, such as the proxy mode, when it is transmitting a byte message, by changing it to operate, thereby disabling or reallocating the call resource allocated to infinite looping Therefore, the resource shortage of the communication channel can be solved.

100: calling terminal 200: call service control device
210: P-CSCF 220: S-CSCF
230: I-CSCF 300: Application service device
310: first application service apparatus 320: second application service apparatus
400:

Claims (17)

Upon receiving a call connection request message from a calling terminal in response to a call connection request to a calling terminal of a calling terminal, the calling terminal confirms whether the called terminal is subscribed to a service and transmits the call connection request message to an application service apparatus corresponding to the subscribed service A call service control device;
When the call connection request message is received from the call service control device while operating in a B2BAU mode, the mobile terminal changes from the B2BAU mode to the proxy mode, counts a forward header value of the call connection request message, And an application service apparatus for transmitting a call connection request message to the call service control apparatus. An application service apparatus operating in a B2BAU (Back to Back User Agent) mode and providing an additional service to a calling terminal or a called terminal,
When the call connection request message is received from the call service control device by interfacing with the call service control device for processing call connection between the calling terminal and the called terminal, the mode is changed from the B2BAU mode to the proxy mode, And transmits the counted value to the call service control device. delete 3. The method of claim 2,
Wherein the application service apparatus comprises an absence management apparatus and a call forwarding management apparatus. delete delete delete delete delete (a) receiving a message including a call connection request from the calling terminal to the called terminal, the call service control device processing a call connection between the calling terminal and the called terminal;
(b) confirming that the call service control apparatus is in the absence of the called terminal;
(c) transmitting the message to the absence management apparatus, wherein the call service control apparatus provides a missed service;
(d) counting a forward header value of a message received from the call service control apparatus by the absence management apparatus and transmitting the message to the call service control apparatus;
(e) confirming that the call service control apparatus joins the call forwarding service of the called terminal;
(f) transmitting the message to the call transferring management apparatus in which the call service control apparatus provides the call transfer service;
(g) counting a forward header value of a message received from the call admission control apparatus from the call service control apparatus, and transmitting the message to the call service control apparatus. 11. The method of claim 10,
In step (c), the call service control device counts a forward header value of the message, and then transmits the message to the absence management device,
Wherein the call service control apparatus counts the forward header value of the message and then transmits the message to the call forwarding management apparatus in step (f). 11. The method of claim 10,
When the called terminal is forwarded to its own number,
Wherein the absence management apparatus and the call transfer management apparatus further execute looping for repeatedly exchanging the message with the call service control apparatus,
Wherein the looping step ends when the forward header value of the message reaches a predetermined value by the count. 11. The method of claim 10,
Wherein the call service control device is a SIP-based call session control device. A method of preventing infinite looping in an application service apparatus operating in a B2BAU (Back to Back User Agent) mode and providing an additional service to a calling terminal or a called terminal,
Receiving the call connection request message from the calling terminal to the called terminal from the call service control device;
Counting a forward header value of a call connection request message received from the call service control apparatus after the application service apparatus changes from the B2BAU mode to the proxy mode;
Wherein the application service apparatus transmits a call connection request message having a counted forward header value to the call service control apparatus. 15. The method of claim 14,
Further comprising performing looping in which the call connection request message is repeatedly exchanged between the application service apparatus and the call service control apparatus,
And if the forward header value of the message reaches a predetermined value according to the count, the looping step is terminated. delete 15. The method of claim 14,
Wherein the counting step performs a positive count in which a forward header value of the message is decreased by one unit or a positive count in which a forward unit value is incremented by one unit.

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