TWI404384B - Ip multimedia subsystem and message flow control method - Google Patents

Abstract

An IP multimedia Subsystem (IMS) and a message flow control method is provided. A message flow is initialed by an initial user equipment (UE) to communicate with a terminating UE. The S-CSCF determines whether an application server should be invoked. If so, a C-SIF is added to the message flow, monitoring the message flow based on a tFC to determine whether to trigger the application server. If the application server is required, the C-SIF invokes a A-SIF to initialized the application server, thereby the application server is participated in the message flow to provide a service.

Description

Multimedia subsystem and information path control method

The present invention relates to an IP Multimedia Subsystem, and more particularly to a method of controlling an information path.

The Session Initiation Protocol (SIP) was developed to help provide advanced telephony services across the Internet and is part of the IETF standard process. A SIP session can be viewed as a message flow that is transmitted over one or more members in a multicast or unicast manner. SIP defines several kinds of messages: (1) INVITE: invites users to join the session. (B) BYE: Terminate the session. (3) OPTIONS: Request information about server capabilities. (4) ACK: Confirm that the terminal device has received the final response to the INVITE. (5) REGISTER: Provides a map of address resolution, letting the server know the location of other users. (6) CANCEL: Used to cancel the invitation that has not received the final response. The SIP protocol is increasingly favored by the industry for its simplicity, ease of expansion, and ease of implementation. It is gradually becoming an important agreement in the field of Next Generation Network (NGN) and 3G Multimedia Subsystem (IMS). .

Figure 1a is a diagram of a conventional multimedia subsystem architecture. In an IMS network 100, various functional blocks are included, such as a Serving Call Session Control Function (S-CSCF) 140, an Intranet User Server (HSS) 160, an I-CSCF 170, and a P-CSCF 180. The I-CSCF 170 is dedicated to access an off-net user, such as the user device 102, accessing from another SIP network. The P-CSCF 180 is dedicated to access intranet users of the IMS network 100 itself, such as user devices 104 and 106. In fact, the off-net user device 102 must also access the IMS network 100 through its own network functions (such as P-CSCF and S-CSCF), which are omitted in the figure. The S-CSCF 140 is responsible for hosting the information path that is transferred between functions. In the HSS 160, an initial filtering rule (iFC) 162 is included for storing various trigger parameters (SPT) set by users in the network. For example, if a user device 106 subscribes to a service provided by an application server 130, the subscription information is stored in the iFC 162. When the information path associated with the user device 106 is initiated, the S-CSCF 140 downloads the iFC 162 from the HSS 160 and triggers the application server 130 to intervene to process the information path.

Figure 1b is a schematic diagram of a conventional information path. Since the IMS network 100 contains various conventional functional blocks, it is simplified here. The user device 102 accesses the IMS network 100 through an Internet (not shown) to which the user outside the IMS network 100 is located. User devices 104 and 106 represent the in-network users of the IMS network 100. The application server 130 may be a local service belonging to the IMS network 100, or may be a service provided by a third party, and thus represented as a unit block independent of the IMS network 100. Assuming that a connection is to be established between the user devices 102 and 106, and the user device 106 is not a subscriber of the application server 130, the information path between the two is P _A , and no message exchange is bypassed to The application server 130. Assuming that the user device 106 is a subscriber of the application server 130, the S-CSCF 140 in the IMS network 100 triggers the iFC 162 in the HSS 160 when the user devices 102 and 106 are connected. Application server 130. The information path P _B between the user devices 102 and 106 then passes through the application server 130, thereby enabling the application server 130 to monitor the dialog state of the user devices 102 and 106 to perform the corresponding service.

Figure 1c is a conventional information path control method. For example, the application server 130 can be a call forwarding service for the user device 104 to answer the call when the user device 106 is unable to answer the call. In step 101, an information path is initialized by taking the architecture of FIG. 1a as an example. In step 103, the user device 102 sends an invitation to the call (INVITE) to request a call with the user device 106 via the IMS network 100. In step 105, the S-CSCF 140 in the IMS network 100 determines whether the user device 106 is a subscriber of the application server 130 based on the iFC 162 in the HSS 160. If the user device 106 is not subscribed to the electrical transfer service, then step 109 is performed, and the user device 102 communicates with the user device 106 through the information path P _A without bypassing the application server 130. If the user device 106 has the call forwarding service of the subscription application server 130, the S-CSCF 140 activates the application server 130 to cause the user devices 102 and 106 to communicate through the information path P _B bypassing the application server 130. . In step 107, after the application server 130 is started, the information path P _B is intercepted to determine when the call forwarding service is triggered. If the user device 106 is in a busy state, it will respond to a busy message (eg, 486 busy here) via the information path P _B . When the application server 130 intercepts the busy message, the process proceeds to step 111, and the call invitation sent by the user device 102 is forwarded to the user device 104. Thereby, the user device 102 and the user device 104 establish an information path P _C and communicate with each other under the control of the application server 130. In contrast, if the user device 106 can answer the call normally, the application server 130 proceeds to step 113 to cause the user device 102 and the 106 to communicate with each other through the information path P _B .

Summarizing the above process, the IMS network 100 will string more than one application server 130. If the user device 106 subscribes to more than one application server 130, the information path will be swept between multiple application servers 130. Go out.

The present invention provides an information path control method. In a multimedia subsystem of an embodiment of the present invention, an intranet user server (HSS) provides an initial filtering rule (iFC). A Serving Call Session Control Function (S-CSCF) can control an information path based on the iFC. A core service calling function (C-SIF) mediates the exchange of information between the S-CSCF and an application server according to a trigger filtering rule (tFC) and an execution filtering rule (eFC). An application service calling function (A-SIF) is used to mediate the exchange of information between the C-SIF and the application server.

When a user registers with the S-CSCF, the S-CSCF first loads the initial filtering rule (iFC) of the user from the HSS, and then determines which application services the user subscribes to. If the originating device or the terminal device of the information path is a subscription user of an application server, the S-CSCF joins the C-SIF to the information path. After the C-SIF joins the information path, it monitors the information path and determines whether the application server needs to be triggered according to the tFC. If the C-SIF needs to trigger the application server according to the tFC, the application server is initialized through the A-SIF, so that the application server joins the information path to provide a service.

Another embodiment of the present invention is an information path control method based on the above multimedia subsystem. First, an information path is initiated by a start device for communicating with a terminal device via an S-CSCF. Then, the S-CSCF determines whether the starting device or the terminal device is a subscription user of an application server according to an initial filtering rule (iFC). If the originating device or the terminal device of the information path is a subscription user of the application server, a C-SIF is added to the information path to mediate information exchange between the S-CSCF and the application server. The information path is monitored by the C-SIF and judged whether it is necessary to trigger the application server according to a tFC. If the C-SIF needs to trigger the application server according to the tFC, the information exchange between the C-SIF and the application server is mediated through the A-SIF, and the application server is initialized by the A-SIF to make the application server Join the information path to provide the service.

Figure 2a is a diagram of the multimedia subsystem architecture of the present invention. In an IMS network 200, an in-network user server (HSS) 260 is included to provide an initial filtering rule (iFC). A Serving Call Session Control Function (S-CSCF) 240 is used to control an information path based on the iFC. One or more application servers 230 may be included in the system to provide various application services. In this embodiment, an application server 230 is taken as an example. Similar to the conventional architecture, the IMS network 200 also includes a proxy call session control function (P-CSCF) 280 for communicating with in-network users such as user devices 204 and 206. An Incoming Call Session Control Function (I-CSCF) 270 is used to communicate with external users such as user device 202 outside of the IMS network 200. In addition, the present invention proposes a set of Core Service Summoning Capabilities (C-SIF) 210 and Application Service Summoning Capabilities (A-SIF) 220 for intervening between the S-CSCF 240 and the application server 230. The C-SIF 210 is disposed in the IMS network 200 and can filter unnecessary message wrapping to the application server 230 according to a trigger filtering rule (tFC) 252 and an execution filtering rule (eFC) 254. The settings of tFC 252 and eFC 254 can be divided into two ways. One is to use standard HSS for storage, and the other is to set and store separately without changing the standard practice. The A-SIF 220 is mainly designed at the front end of the application server 230 and used in conjunction with the C-SIF 210. Since the application server 230 may originate from various unused service providers, the area in which it is located is not limited to be the same as the IMS network 200. Therefore, the cost of routing between the IMS network 200 and the application server 230 may be high. The A-SIF 220 is configured in the same area as the application server 230, and communicates with the C-SIF 210 in a more efficient manner to achieve the function of the intermediary agent.

Figure 2b is a schematic diagram of the information path of the present invention. Assuming that the user device 202 is a starting device (initiator) of an information path and the user device 204 is a terminal device (target), the information path may be in the case of the subscription service according to the subscription service. Known information path P _A , P _B or P _C . However, in the present invention, the message that is not required to be routed to the application server 230 is omitted by the C-SIF 210, shortening the information path to P _D or P _F . In accordance with conventional standard procedures, when a user is online (e.g., user device 204), an initial filtering rule (iFC) 262 corresponding to the user in HSS 260 is downloaded to S-CSCF 240. When the information path is initiated, the S-CSCF determines whether to include the C-SIF 210 in the information path based on the iFC 262. In this embodiment, if the information path is initiated by the user device 204, the user device 204 is the originating device that initiated the information path. In contrast, if the information path is initiated by an external device (eg, user device 202) and the target is directed to the user device 204, the user device 204 is the terminal device of the information path. According to the iFC 262, the S-CSCF 240 can determine whether the user device 204 is a subscription user of the application server 230 according to the received message content. If so, the S-CSCF 240 sends a third party registration to the C-SIF 210 in accordance with the settings of the iFC 262, causing the C-SIF 210 to join the information path. Thus, an information path P _D is formed between the user devices 202 to 204, the path of which includes the C-SIF 210. The C-SIF 210 then loads the corresponding tFC in accordance with the application service that may be triggered, thereby monitoring the communication process in the information path P _D to trigger the service at the appropriate time.

The C-SIF 210 can monitor the information path P _D instead of the application server 230 and determine whether the application server 230 needs to be triggered based on the tFC 252. Since the C-SIF 210 is disposed at the near end of the S-CSCF 240, the cost of message routing can be reduced. If the C-SIF 210 determines, according to the tFC 252, that the information in the information path P _D needs to trigger the application server 230, the application server 230 is initialized through the A-SIF 220, so that the application server 230 joins the information path. Provide services. In this embodiment, the application server 230 can be an incoming call transfer service for automatically transferring the user device 204 to another user device 206 when the user device 204 is unable to answer the call. When the user device 204 can answer the call, the information paths of the user devices 202 and 204 are P _D , and the path does not bypass the application server 230. When the user device 204 is unable to answer the call, the application server 230 is started, and the user devices 202 and 206 establish an information path P _E around the application server 230 to communicate with each other.

Further, the C-SIF 210 can monitor the information path P _E according to the eFC 254, and directly transfer the message that is not required to be routed to the application server 230 to the destination. Therefore, a shorter information path P _F can be further formed for the user device 202 to communicate with the 206.

The C-SIF 210 proposed by the present invention, in addition to filtering the message sent to the application server 230 via the S-CSCF 240 according to the eFC 254 or the tFC 252, forwards the message not destined to the application server 230 back to the S-CSCF. In addition to 240, the omitted messages will be temporarily stored. Since some of the omitted messages are necessary to initialize the application server 230, if it is necessary to enable the application server 230 during a later session, the temporarily stored message must be retransmitted to the application server 230. The A-SIF 220 proposed in the present invention is used to proxy these temporarily stored messages. The detailed dialog process between C-SIF 210 and A-SIF 220 is illustrated in Figure 3.

The information paths P _D , P _E and P _F described in Figure 2b are bidirectional. The originating device may be an in-network user in the IMS network 200, such as the user device 204 or 206, or may be an off-net user such as the user device 202. The information paths are substantially bypassed by I-CSCF 270, S-CSCF 240, P-CSCF 280, selectively wound to the C-SIF 210 according to the initial filtering rules, and selectively wound according to eFC 254 and tFC 252. To the application server 230, the final delivery destination. The tFC 252 and eFC 254 shown in Figure 2a are stored in the database 250, but may be stored directly in the conventional HSS 260 with the iFC 262.

The second c-picture is the information path control method of the present invention. It is assumed that the application server 230 is a call forwarding service, and when the user device 204 is unable to answer the call, the user device 206 is transferred to answer the call. In step 201, an information path is initialized by taking the architecture of FIG. 2a as an example. In step 203, the user device 202 sends a call invitation to talk to the user device 204 through the IMS network 200. In step 205, the S-CSCF 240 in the IMS network 200 determines whether the user device 204 is a subscriber of the application server 230 based on the iFC 262 in the HSS 260. If the user device 204 is not subscribed to the electrical transfer service, proceed to step 209, the user devices 202 and 204 communicate through the traditional information path P _A without bypassing the C-SIF 210 or the application. Server 230. If the user device 204 has the call forwarding service of the subscription application server 230, then in step 207, the S-CSCF 240 activates the C-SIF 210 to cause the user devices 202 and 204 to pass through the C-SIF. 210 information path P _D to communicate. In step 211, after the C-SIF 210 is activated, the behavior of the original application server 230 is proxied, the information path P _{D is} intercepted, and the tFC 252 is used to determine when the call forwarding service is triggered. If the user device 204 is not in the busy state, proceed to step 213, the C-SIF 210 does not forward the message to the application server 230, but directly forms a shorter information path P _D to the user device 202 and Between 204. If the user device 204 is in a busy state, a busy message (for example, "486 Busy Here") is sent through the information path P _D . When the C-SIF 210 intercepts the busy message, it indicates that it is necessary to trigger the application server 230 to perform the call forwarding service, and the call invitation sent by the user device 202 is forwarded to 206 to form the information path P _E .

The next process is all done in the event that the application server 230 has triggered. In step 215, the C-SIF 210 determines, based on the set of eFCs 254, whether the message transmitted in the information path P _E needs to be routed to the application server 230. If there is the information of the path P _E eFC 254 that match the message, step 217, the user device 202 using the information of the path P _E 206 communicate with each other. The eFC 254 includes at least an execution point field for defining the type of SIP message and a processing action field for defining the handler. There may be various SIP requirements in the information path P _E , such as CANCEL, ACK, UPDATE, etc., as well as various SIP responses, such as 1XX, 2XX, 3XX, and the like. When the SIP message received by the C-SIF 210 conforms to the value of the execution point field in the eFC 254, the processing procedure defined by the corresponding processing action field is executed. The handler can be either INTERRUPT, NOTIFY, or NULL. For example, if the INTERRUPT handler is triggered, the C-SIF 210 can pause the call and forward the message to the application server 230 via the A-SIF 220. After the application server 230 processes the message, it sends a reply, and then passes back to the C-SCSF 240 through the A-SIF 220 and the C-SIF 210, and then the call is continued. If the handler is NOTIFY, the C-SIF 210 does not suspend the call, but instead passes the message back to the C-CSCF 240 to continue the call and forwards the notification to the application server 230 via the A-SIF 220. If the handler is NULL, the C-SIF 210 does not perform any processing and forwards the message directly back to the S-CSCF 240. On the other hand, if there is no message in the information path that meets the requirements of eFC 254, indicating that the message can be omitted from the application server 230, then step 219 is performed, and the C-SIF 210 removes the application server 230 from the information. The path is removed to form an information path P _F for the user devices 202 and 206 to communicate with each other. In summary, with the C-SIF 210 and the A-SIF 220 of the present invention, only the information that actually needs to be used by the application server 230 will go through the information path P _E , and most of the other messages are short information paths P. _D or P _F .

Figure 3 is a flow chart of the mediation function of A-SIF 220 and C-SIF 210. In the information path P _E , the exchange of information between the application server 230 and the S-CSCF 240 is mediated through the C-SIF 210 and the A-SIF 220. The exchange of information between C-SIF 210 and A-SIF 220 mainly includes three types: PUBLISH, SUBSCRIBE, and NOTIFY. The C-SIF 210 temporarily stores messages that are not forwarded to the application server 230 but have important functions, such as a series of instructions for initializing the application server 230. In step 301, the application server 230 is launched based on the needs in the communication process. In step 303, the C-SIF 210 first packages the temporarily stored message into a PUBLISH request and transmits it to the A-SIF 220. Next, in step 305, the A-SIF 220 unpacks the message in the distribution request to simulate the dialog defined by the standard specification, and causes the application server 230 to initialize and enter the service state. After the application server 230 enters the service state, it also communicates with the outside world through the A-SIF 220. In step 307, the A-SIF 220 will package the signal sent by the application server 230 into a SUBSCRIBE request and transmit it to the C-SIF 210. The C-SIF 210 then unpacks the message in the subscription request and forwards it to the S-CSCF 240 to interface with the original information path. On the other hand, in step 309, for the message in the information path to be transmitted to the application server 230, the C-SIF 210 will package it as a NOTIFY request and transmit it to the A-SIF 220. The A-SIF 220 unpacks the message in the notification request and forwards it to the application server 230, thereby simulating the traditional conversation process between the application server 230 and the S-CSCF 240, so that the application server 230 can be executed normally.

4a through 4f are a call transfer function implemented in accordance with the present invention. 4a and 4b are arranged side by side as the first group, 4c and 4d are side by side as the second group, 4e and 4f are side by side as the third group, and then the first, second and third The group diagram is laid out side by side into a complete flow chart. Assuming that the application server 230 provides a call forwarding function, the present invention is illustrated in the representation of a SIP communication protocol. First, the user device 202 sends an invitation message INVITE (steps 1 to 3) from the network system "A Home" to which it belongs (also including the corresponding P-CSCF and S-CSCF) to talk to the user device 204. In steps 4 to 6, the invitation message is accessed through the I-CSCF 270 in the network system "B Home", and the S-CSCF determines from the SFC CS 262 that the user device 204 has the call forwarding of the subscription application server 230. service. However, the C-SIF 210 does not forward the invitation message to the application server 230 (steps 7 through 8), but instead drops it to the user device 204. In this example, the user device 204 is in a busy state, so a SIP message with the code "486 Busy Here" is lost (steps 11 through 14). The C-SIF 210 detects this message through the S-CSCF 240, and then officially launches the application server 230 for call forwarding service (steps 15 through 17). In this embodiment, the application server 230 and the A-SIF 220 may be located in another IMS network "AS Home". The C-SIF 210 issues a PUBLISH message to the A-SIF 220 (steps 18 to 19), causing the A-SIF 220 to initialize the application server 230 (steps 20 to 25). Finally, the A-SIF 220 reports the C-SIF 210 in the manner of SUBSCRIBE (steps 26 to 27). At this point, the user devices 202 and 206 begin to communicate (steps 28 through 43). Part of the message does not need to be circulated to the application server 230, so the C-SIF 210 removes the application server 230 from the information path, simplifying the information path. For example, the SIP message "P-CSCF 180" of steps 36 to 43. On the other hand, part of the message needs to be forwarded to the application server 230, for example, the SIP message "200" in steps 44 to 46, and the C-SIF 210 forwards the SIP message "200" to the application server 230 in the NOTIFY manner. 47 to 50). At the same time, the C-SIF 210 also forwards the SIP message "200" back to the user device 202 without waiting for a response from the application server 230 (steps 51 through 55). Steps 56 to 62 illustrate that the ACK sent by the user device 202 does not pass through the application server 230, but is forwarded directly to 206 after being bypassed to the C-SIF 210. The last steps 63 to 83 are a hang-up procedure. The C-SIF 210 determines that the SIP message "BYE" needs to be forwarded to the application server 230, so that the A-SIF 220 is notified in the manner of NOTIFY (steps 67 to 68), and the A-SIF 220 hangs up the application server 230 again. Connected analog conversations (steps 69-72). Steps 74 through 83 illustrate the hangup steps that are not required to be routed to the application server 230 and processed directly by the C-SIF 210.

The architecture proposed by the present invention primarily saves the cost of routing unnecessary messages to the application server 230. In addition, the communication between C-SIF 210 and A-SIF 220 is also carried out in a more efficient manner. The applicable application service is not limited to call forwarding. For example, the application server 230 can be an online recording service for recording conversations between the user devices 202 and 204. During the conversation between the user devices 202 and 204, the application server 230 is initially in a non-boot state, so the information path is not circulated to the application server 230. Until the user device 202 enters an instruction to start recording, the information path begins to be routed to the application server 230 for recording. When the user device 202 inputs an instruction to stop recording, the information path returns to the state of not being circulated to the application server 230.

Furthermore, the C-SIF 210 and A-SIF 220 proposed by the present invention are transparent to the S-CSCF 240 and the application server 230. Since the C-SIF 210 and the A-SIF are in the middle of the S-CSCF 240 and the application server 230, intercepting and processing all the passed messages, so that it can be directly compatible with the traditional system architecture, without rewriting or designing S- CSCF 240 and application server 230. In summary, the present invention provides an efficient multimedia subsystem information path control method through the elastic setting of eFC and tFC, and the combination of C-SIF 210 and A-SIF 220.

100. . . IMS network

102, 104, 106. . . User device

130. . . application server

140. . . S-CSCF

160. . . HSS

162. . . iFC

170. . . I-CSCF

180. . . P-CSCF

200. . . IMS network

202, 204, 206. . . User device

210. . . C-SIF

220. . . A-SIF

230. . . application server

240. . . S-CSCF

250. . . database

252. . . tFC

254. . . eFC

260. . . HSS

262. . . iFC

270. . . I-CSCF

280. . . P-CSCF

Figure 1a is a conventional multimedia subsystem architecture diagram;

Figure 1b is a schematic diagram of a conventional information path;

Figure 1c is a conventional information path control method;

Figure 2a is a diagram of the multimedia subsystem architecture of the present invention;

Figure 2b is a schematic diagram of the information path of the present invention;

Figure 2c is an information path control method of the present invention;

Figure 3 is a flow chart of the intermediary functions of A-SIF and C-SIF;

Figure 4 is a call transfer function implemented in accordance with the present invention.

200~. . . IMS network

202, 204, 206~. . . User device

210. . . C-SIF

220. . . A-SIF

230. . . application server

240. . . S-CSCF

250. . . database

252. . . tFC

254. . . eFC

260. . . HSS

262. . . iFC

270. . . I-CSCF

280. . . P-CSCF

Claims (21)

A multimedia subsystem, comprising: an in-network user server (HSS) for providing an initial filtering rule (iFC); a service call session control function (S-CSCF) for controlling an information path according to the iFC; a core service calling function (C-SIF) for mediating information exchange between the S-CSCF and an application server according to a trigger filtering rule (tFC) and an execution filtering rule (eFC); an application service calling function (A) -SIF), for arranging information exchange between the C-SIF and the application server; wherein: when the information path is started, the S-CSCF determines, according to the iFC, whether the starting device or the terminal device of the information path is a subscriber of the application server; if the originating device or the terminal device of the information path is a subscription user of the application server, the S-CSCF joins the C-SIF to the information path; after the C-SIF joins the information path, Monitoring the information path and determining whether the application server needs to be triggered according to the tFC; if the C-SIF determines that the application server does not need to be triggered according to the tFC, temporarily storing one of the message paths, and when the application server adds When the path message, transmitted to the application server via the A-SIF the message; and if the C-SIF required to trigger the application server based on the judgment tFC, initialize the application server via the A-SIF, so that the service application The device joins the information path to provide the service, and when the message path has a previously staged message, the message is transmitted to the A-SIF. The multimedia subsystem of claim 1, wherein: if the originating device or the terminal device of the information path is a subscription user of the application server, and the C-SIF determines that the application server does not need to be triggered according to the tFC , the application server is removed from the information path, so that the message is not circulated to the application server. The multimedia subsystem of claim 1, wherein if the application server has triggered a service, and the C-SIF determines, according to the eFC, that a message in the information path is not necessarily circulated to the application server, The C-SIF removes the application server from the information path so that the message is not circulated to the application server. The multimedia subsystem of claim 1, wherein: when the C-SIF initializes the application server through the A-SIF: packaging the temporarily stored message into a PUBLISH request, and transmitting the message to the A-SIF; the A-SIF unpacks the message encapsulated in the release request to simulate a traditional information path to talk to the application server to bring the application server into a service state. The multimedia subsystem of claim 4, wherein after the application server enters a service state, the A-SIF packages the message sent by the application server into a subscription (SUBSCRIBE) request and transmits the message to the C-SIF. ;as well as The C-SIF unpacks the message wrapped in the subscription request and joins the information path. The multimedia subsystem of claim 5, wherein after the application server enters a service state, the C-SIF packages the message to be transmitted to the application server in the information path into a NOTIFY request to The A-SIF is transmitted to the A-SIF; and the A-SIF unpacks the message encapsulated in the notification request, and performs a dialogue with the application server to cause the application server to execute the service. The multimedia subsystem of claim 1, further comprising: a proxy call session control function (P-CSCF) for communicating with users in the multimedia subsystem; and an inquiry call session control function (I-CSCF) for communicating with users outside the network outside the multimedia subsystem. The multimedia subsystem of claim 7, wherein the information device is initiated by the user in the multimedia subsystem, and the information path passes through the P-CSCF. The S-CSCF selectively wraps around the C-SIF according to the initial filtering rule, selectively routes to the application server according to the eFC and the tFC, and finally delivers the terminal device of the information path. The multimedia subsystem of claim 7, wherein the information device is initiated by the external network user outside the multimedia subsystem, and the information path is passed through the I-CSCF. , the S-CSCF, selectively wound according to the initial filtering rule To the C-SIF, the eFC and the tFC are selectively routed to the application server and finally delivered to the terminal device of the information path. The multimedia subsystem of claim 7, further comprising a database for storing the eFC and the tFC. The multimedia subsystem of claim 7, wherein the eFC and the tFC are stored in the HSS. An information path control method for an multimedia subsystem (IMS), comprising: initiating an information path by a starting device for communicating with a terminal device via an S-CSCF; the S-CSCF according to an initial filtering rule (iFC) to determine whether the starting device or the terminal device is a subscription user of an application server; if the originating device or the terminal device of the information path is a subscription user of the application server, adding a C-SIF to the information path, Used to mediate the information exchange between the S-CSCF and the application server; the C-SIF monitors the information path and determines whether the application server needs to be triggered according to a tFC; if the C-SIF does not need to be determined according to the tFC Triggering the application server, temporarily storing one of the message paths, and transmitting the message to the application server through the A-SIF when the application server joins the message path; and if the C-SIF is determined according to the tFC The application server needs to be triggered to provide an A-SIF for mediating the exchange of information between the C-SIF and the application server, and initializing the application server to add the application server. The path information to provide a service, and when the message path When there is one of the previously temporarily stored messages, the C-SIF message is transmitted to the A-SIF. The information path control method of claim 12, further comprising: if the starting device or the terminal device is a subscription user of the application server, and the C-SIF determines that the application server does not need to be triggered according to the tFC, The application server is then removed from the information path to simplify the information path. The information path control method according to claim 12, further comprising: if the application server has triggered the service, but the C-SIF determines that a message in the information path is not required to be routed to the application server according to the eFC, Then the C-SIF removes the application server from the information path to simplify the information path. The information path control method according to claim 12, wherein the step of initializing the application server by the C-SIF through the A-SIF comprises: packaging the temporarily stored message into a publishing request, and transmitting the message to the A- The SIF; and the A-SIF unpack the message in the release request to simulate a traditional information path to talk to the application server to bring the application server into a service state. The information path control method of claim 15, wherein the step of exchanging the A-SIF with the C-SIF intermediary information comprises: after the application server enters a service state, the A-SIF sends the application server Message, packaged into a subscription request, delivered to the C-SIF; The C-SIF unpacks the message wrapped in the subscription request and joins the information path. The information path control method of claim 16, wherein the step of exchanging the A-SIF with the C-SIF intermediary information further comprises: after the application server enters a service state, the C-SIF the information path The message to be transmitted to the application server is packaged into a notification request for transmission to the A-SIF; and the A-SIF unpacks the message in the notification request, and performs a dialogue with the application server to cause the application server to execute service. The information path control method according to claim 12, further comprising: communicating with a user in the network in the multimedia subsystem through a P-CSCF; and transmitting an I-CSCF to the outside of the multimedia subsystem User communication. The information path control method according to claim 18, wherein the starting device is an intra-network user in the multimedia subsystem, and the information path passes through the P-CSCF, and the information path passes through the P-CSCF. The S-CSCF selectively wraps around the C-SIF according to the initial filtering rule, selectively wraps around the eFC and the tFC to the application server, and finally delivers the terminal device of the information path. The information path control method according to claim 18, wherein the information device is initiated by the external network user outside the multimedia subsystem, and the information path passes through the I-CSCF. The I-CSCF, which selectively routes to the C-SIF according to the initial filtering rule, selectively routes to the application server according to the eFC and the tFC, and finally delivers the terminal device of the information path. The information path control method according to claim 12, wherein the eFC and the tFC are stored in a database or an in-network user server (HSS).