AU2003284729B2 - System and method for providing subtitute ringback tone based on intelligent network - Google Patents

Description

WO 2004/073334 PCT/KR2003/002497 1 SYSTEM AND METHOD FOR PROVIDING SUBSTITUTE RINGBACK TONE BASED ON INTELLIGENT NETWORK Technical Field The present invention relates to a call setup precess in a communications network and, more particularly, to a method providing substitute ringback tone for the ringback tone provided to a calling party until a called party answers a call during a call setup process.

Background Art When a calling subscriber originates a call in a communications network, a terminating switch provides a ringback tone until a called subscriber responds to the call.

Recently, a substitute ringback tone service providing substitute tone designated by the phone user instead of uniform ringback tone having a fixed frequency and a fixed intermission period became increasingly popular with the phone users.

Methods for providing the substitute ringback tone are disclosed, for example, in Korean Patent No. 292089 issued 20 March 2001 and entitled METHOD AND APPARATUS FOR GENERATING SUBSTITUTE RINGBACK TONE DESIGNATED BY CALLED PARTY IN TERMINATING SWITCH IN COMMUNICATIONS NETWORK, and Korean Laid-open Patent 2002-56833 published 10 July 2002 and entitled METHOD AND APPARATUS FOR PROVIDED SUBSCRIBER-BASED SUBSTITUTE RINGBACK TONE.

WO 2004/073334 PCT/KR2003/002497 2 FIG. 1 illustrates the substitute ringback tone providing system disclosed in the Korean Patent No. 292089. In the state that the called party is subscribed with the substitute ringback tone providing service, when the calling party requests to set up a call for the called party through the originating switch (O MSC/VLR) 20, the terminating switch 30 detects the service subscription of the called party based on the service subscription information stored in the HLR 10 and sets up an ISUP call to a substitute ringback tone playing server 50 using the routing information stored in the HLR During the process, the terminating switch (T MSC/VLR) 30 provides the service control point (SCP) 40 with interpretation information defined in the Wireless Intelligent Network (WIN), the North American CDMA standard, receives the TLDN which the SCP acquired from the substitute ringback tone playing server 50, and sets up the ISUP call to the substitute ringback tone playing server 50. Subsequently, the substitute ringback tone playing server 50 requests and receives the sound information designated by the called party from the SCP 40, and the substitute ringback tone playing server 50 provides substitute ringback tone corresponding to the sound information to the calling party. The SCP 40 maintains sound information for each subscriber as a table 42 and provides the information to the substitute ringback tone playing server 50. Afterwards, when the called party answers the call, the terminating switch 30 releases the call channel to the substitute ringback tone playing server 50 and makes the called party be connected to the calling party.

FIG.2 illustrates the substitute ringback tone providing system disclosed in the Korean Laid-open Patent 2002-56833. In the state that the called party is subscribed with WO 2004/073334 PCT/KR2003/002497 3 the substitute ringback tone providing service, when the calling party requests to set up a call for the called party through the originating switch 20, the terminating switch 60 detects the service subscription of the called party based on the service subscription information stored in the HLR 10 and sets up an ISUP call to a substitute ringback tone playing server 70 using the routing information stored in the HLR 10. The substitute ringback tone playing server 70 requests the sound information designated by the called party from the playing control server 80, and the substitute ringback tone playing server 70 provides substitute ringback tone corresponding to the sound information to the calling party. The playing control server 40 maintains sound information for each subscriber as a table 82 and provides the information to the substitute ringback tone playing server 70. Afterwards, when the called party answers the call, the terminating switch 60 releases the call channel to the substitute ringback tone playing server 70 and makes the called party be connected to the calling party.

Conventionally, however, when the called party answers during the play of the substitute ringback tone, the terminating switch has to request to release the ISUP call to the substitute ringback tone playing server, and then transmit a response message to the originating switch so as to set up a call channel between the calling party and the called party. Since the switching system is to be equipped with an additional function in addition to the ordinary functions of setting up or releasing a call among subscribers and routing to another switching system, it is necessary to modify the switching system itself. Thus, a communications carrier who wishes to introduce the service has to replace or modify on a large scale the switching system, the carrier has to expend large costs. Even worse, the WO 2004/073334 PCT/KR2003/002497 4 carrier cannot introduce the service if the vendor does not harmoniously cooperate with the carrier. Furthermore, the modified function of the switch increases the dependency of the carrier to the vendor in addition to the costs of the system to be purchased later.

Desclosure of the invention To solve the above problem, the object of the present invention is provide a system method for providing substitute ringback tone without the change or substantial modification of the switching system.

The substitute ringback tone providing system for achieving the above object is a mobile communications system which adopts or supports similar functions of an intelligent network-based protocol such as "CustomizedApplications for Mobile network Enhanced Logic (CAMEL) Phase 4. CAMEL Application Part (CAP) Specification (Release 5) that is published Dec. 2002 at 3GPP (The 3rd Generation Partnership Project). A terminating switch which can be connected to a substitute ringback tone playing server storing a sound file designated by a subscriber processes a terminating call in accordance with a predetermined call state model. A service control point is programmed to be equipped with a service logic for a plurality of detection points such as a call attempt detection point and an answering detection point in the call state model. The service control point controls the call process of the terminating switch in response to a service request from the terminating switch. A home location register stores service subscription information of each subscriber and information for routing to the substitute ringback tone playing server.

In the system, when receiving a call connection request from a calling party, the WO 2004/073334 PCTIKR2003/002497 terminating switch suspends the call process to the subscriber and provides the service control point with a service request including the subscriber identification information, the service subscription information, and the routing information. The service control point provides the terminating switch with the subscriber identification information and the routing information to make the terminating switch to be connected to the playing server using the routing information and the subscriber identification information, so that the playing server provides the substitute ringback tone designated by the subscriber to the calling party. When the subscriber answers, the terminating switch sends a service request message to the service control point based on subscriber identification information included in the answer and releases the call to the substitute ringback tone playing server and sets up a call to the subscriber under the control of the service control point, so that a call channel is set up between the calling party and the subscriber.

According to an aspect of the present invention, a predetermined substitute ringback tone information server stores sound information designated by the subscriber.

The substitute ringback tone playing server acquires the sound information for the subscriber from the substitute ringback tone information server and provides the substitute ringback tone corresponding to the sound information to the calling party.

The substitute ringback tone providing method in such a system is as follows. First, when receiving a call connection request from the calling party, the terminating switch suspends the call process to the subscriber and provides the service control point with the service request including the subscriber identification information, the service subscription information, and the routing information. When the service subscription information WO 2004/073334 PCTIKR2003/002497 6 indicates the substitute ringback tone, the service control point provides the terminating switch with the subscriber identification information and the routing information to make the terminating switch to be connected to the playing server using the routing information and the subscriber identification information. The substitute ringback tone playing server acquires the sound information for the subscriber from the substitute ringback tone information server and provides the substitute ringback tone corresponding to the sound information to the calling party. When the subscriber answers, the terminating switch sends the service request message to the service control point based on the subscriber identification information included in the answer and releases the call to the substitute ringback tone playing server and sets up a call to the subscriber under the control of the service control point, so that a call channel is set up between the calling party and the subscriber.

The terminating switch may acquire and store the service subscription information of the subscriber and the routing information before receiving the call setup request from the calling party. Alternatively, however, the terminating switch may acquire the service subscription information of the subscriber and the routing information from the home location register after receiving the call setup request from the calling party.

Preferably, the service control point determines whether the terminating switch has a capability of generating and controlling of a call to the substitute ringback tone playing server for carrying out the substitute ringback tone service, and provides the routing information and the subscriber identification information to the terminating switch only when the terminating switch has the capacity. It is preferable that the terminating switch WO 2004/073334 PCTIKR2003/002497 7 provides function specification information of the terminating switch to the service control point to support the determination of the service control point.

When detecting the detection points, the terminating switch generates trigger identification information, requests the service analysis and the translation of routing information to the service control point, and performs the call processing under the control of the service control point. Such detection points include the call attempt detection point and the answering detection point. When the call attempt detection point is detected and the service subscription information corresponds to the substitute ringback tone service, the service control point generates a new leg for accessing the substitute ringback tone playing server. When the answering detection point is detected, the service control point recovers the original leg for the subscriber so that the call from the caller is connected to the subscriber. Since such a function can be implemented by a simple change of the program in the service control point, any change or modification of the switching system (MSC or VLR) is obviated.

is According to another aspect of the present invention, the service control point stores the sound information for the subscriber. The service control point provides the sound information for the subscriber to the substitute ringback tone playing server so that the playing server provides the substitute ringback tone corresponding to the sound information to the calling party. Here, an agent for providing the sound information stored in the service control point to the playing server in response to a request of the playing server may be equipped in the service control point, the playing server, or both.

WO 2004/073334 PCT/KR2003/002497 8 Brief Description of the Drawings The above objectives and advantages of the present invention will become more apparent by describing in detailed preferred embodiments thereof with reference to the attached drawings in which: FIG. 1 illustrates an example of conventional substitute ringback tone providing systems; FIG. 2 illustrates another example of conventional substitute ringback tone providing systems; FIG. 3 illustrates an embodiment of a mobile communications system for implementing the substitute ringback tone providing method of the present invention; FIG. 4 is a state transition diagram showing a basic call state model on a terminating switch defined in the CAMEL (Customized Application for Mobile network Enhanced Logic) of the 3GPP (The 3rd Generation Partnership Project); FIGS. 5A and 5B are flowcharts showing an embodiments of the substitute ringback tone providing method implemented in the system of FIG. 3; FIG. 6 illustrates another embodiment of a mobile communications system for implementing the substitute ringback tone providing method of the present invention; FIGS. 7A and 7B are flowcharts showing an embodiments of the substitute ringback tone providing method implemented in the system of FIG. 6; and FIG. 8 illustrates yet another embodiment of a mobile communications system for implementing the substitute ringback tone providing method of the present invention.

Embodiments WO 2004/073334 PCT/KR2003/002497 9 The mobile communications system shown in FIG.3 is a GSM system which adopts a protocol defined in "Customized Applications for Mobile network Enhanced Logic (CAMEL) Phase 4. CAMEL Application Part (CAP) Specification (Release published on Dec. 2002 by 3GPP (The 3rd Generation Partnership Project) organized by ARIB, CWTS, ETSI, T1,TTA, and TTC. However the present invention is not restricted by above the system, the present invention may be embodied by another system which is embodied on intelligent network providing function similar to the regulation.

Referring to FIG. 3, Home Location Register (HLR) 100 is a register having a function of an intra-network database and maintains information of subscribers and locations of subscribers as known in the art. Particularly, according to present invention, the HLR stores the service subscription information of subscibers and the routing information for routing a call to the substitute ringback tone playing server 130 as subscriber profile information. Even though a single HLR provides services to both an originating switch (OMSC/VLR) 110 and a terminating switch (TMSC/VLR)120 in FIG. 3, both switches may be served by respective HLRs.

The originating switch 110 and the terminating switch 120 are connected to each other through a No.7 signalling network and are connected to HLR 100. When a subscriber terminal carries out location registration in its service area, the terminating switch 120 registers the location information in the HLR 100. At this time, the terminating switch 120 receives the service subscription information of the subscriber and the routing information for routing a call to the substitute ringback tone playing server 130 to store in its Visitors Locations Register (VLR), and provides the substitute ringback tone service WO 2004/073334 PCTIKR2003/002497 using such information whenever a call terminating to the terminal is generated as described below. As the location of the calling party and the called party, the role of the originating switch 110 and the terminating switch 120 may be exchanged, and a single switch can carry out the roles of the two switches when a calling party and a called party are located in its service area.

A service Control Point (SCP) 122 connected to the terminating switch 120 through the of No.7 signalling network performs the call control functions of: the qualification test of the information received from the terminating switch 120 and the interpretation of routing information. Particularly, the SCP 122 connected to terminating switch 120 controls the substitute ringback tone service according to the CAMEL Phase 4 and CAP Release The sound information server 130 is equipped with the sound information table 132 for storing sound information selected by each subscriber and provides the sound information to the playing server 140 upon a request of the playing server 140. The sound information server 130 includes or is connected to a web server, a WAP server and an ARS system which enables subscribers to subscribe or withdraw the services and alter the sound. Since the configuration of such systems is well known in the art and any person skilled in the art can make it easily, detailed description of the systems is omitted.

The playing server 140 is equipped with various sound files. When an ISUP call is set up between the terminating switch 120 and the playing server 140, the playing server 140,queries the sound information designated to the called party to the sound information server 130, and provides substitute ringback tone corresponding to the sound information WO 2004/073334 PCT/KR2003/002497 11 from the sound information server 130 through the terminating switch 120 and originating switch 110.

As described above, the terminating switch 120 performs a call process in accordance with the protocol of CAMEL. FIG. 4 shows a Basic Call State Model in the terminating switch 120 (TBCSM) defined in the CAMEL. The call state model shown in FIG. 4 includes three repetitive points-in-call (PIP), a "T_Null" state, a "Terminating Call Handling" state, and a "T_Active" state, among which states three detection points (DPs) are set. Also, the call state model includes a "T Exception" state for processing an exceptional state. Table. 1 summarizes the detection points.

Table 1: Detection Points (DPs) Detection Point Number Description TerminatingAttemptAuthorized DP12 T-CSI is analyzed.

T_Answer DP 15 Call is accepted and answered by called party.

A disconnect indication is received T_Disconnect DP17 from the calling party or the called party.

The states shown in FIG. 4 will be described briefly. The "T_Null" state, which is entered after a preceding call is terminated and cleared after the detection point DP17) or the basic exceptional state is processed in the "TException" state, is a state for performing the operations of: initializing the interfaces with exterior device, receiving an ISUP initial address message, and analyzing information to transmit routing information to the HLR. This state is terminated when a response is received from the HLR and the analysis of the T_CSI is completed or an exceptional condition such as a call abandonment WO 2004/073334 PCTIKR2003/002497 12 of the calling party happens.

The "Terminating Call Handling" state, which is entered when a response is received from the HLR and the analysis of the subscription information of the subscriber is completed after the detection point DP12), is a state for performing the operations of: analyzing the response of the HLR, and sending a ring signal to the called party until the called party answers. This state is terminated when the called party answers the call or an exceptional condition such as a call abandonment of the calling party happens.

The "TActive" state, which is entered when the called party answers the incoming call after the detection point DP15), is a state for performing the operations of: setting up a call channel between the calling party and the called party set, supervising the call process, and waiting for the completion of the call. This state is terminated when the termination of the call is notified by the called party or the calling party or an exceptional condition happens.

The terminating switch 120 process all the terminating calls according to such a call state model. Whenever a certain detection point is detected, the terminating switch 120 generates triggering identification information to request the service analysis and interpretation of the routing information to the SCP 122. Particularly, according to the present invention, when receiving an Initial Address Message (IAM) for the terminal subscribed with the substitute ringback tone service from the originating switch 110, the terminating switch 120 suspends the call process, generates the triggering identification information for the initial call attempt, acquires the routing information and the service subscription information for the called party fr-om the HLR 100 according to the triggering WO 2004/073334 PCT/KR2003/002497 13 identification information, and provides the triggering identification information to the SCP 122 to be controlled by the SCP 122. Here, the routing information and service subscription information of the called party may be received from the HLR 100 and stored in the VLR previously.

FIGS. 5A and 5B show the process of providing substitute ringback tone according to an embodiment of the present invention. The process shown in the figures generally includes steps of initial addressing for setting up a call (steps 200 through 208), steps of playing substitute ringback tone (steps 210 through 236), answering steps (steps 238 through 252).

First, a phone user who wishes to user the substitute ringback tone service of the present invention subscribes to the service through the Internet or the ARS. When a new user subscribes to the service or an existing subscriber alters the sound information, the sound information server 130 or an another server responsible for the service subscription process stores the sound information for the subscriber, the sound file or the sound code designated by the subscriber, in the sound information table 132 of the sound information server 130.

In this state, when an arbitrary calling party calls the service subscriber, the orignating switch 110 corresponding to the calling party requests the location information of the called party of the HLR 100 (step 200). In step 202, the HLR 100 requests routing information for the called party to the terminating switch 120 corresponding to the called party. The terminating switch 120 responds to the request of the HLR 100 by providing the routing information including Temporary Local Directoty Number (TLDN) (step 204).

WO 2004/073334 PCT/KR2003/002497 14 Here, the TLDN is an identifier temporarily given to the called party during the call setup process. In step 206, the HLR 100 provides the originating switch 110 with the location information including the routing information.

The orginating switch 110 attempts an ISUP call by transmitting the Initial Address Message (IAM) to the terminating switch 120 (step 208). The Initial Address Message includes the identification imformation of the calling party MIN of the calling party) and that of the called party.

As mentioned above, the terminating switch 120 complies with the Basic Call State Model (TBCSM) defined in the CAMEL and illustrated in FIG. 3, and has a detection point DP12 for the initial call attempt "Terminating_Attempt_Authorized" state).

Upon receiving the Initial Address Message, the terminating switch 120 generates the triggering identification information (for example, trigger type information) for the initial call attempt (step 210). Subsequently, the terminating switch 120 acquires the service key and the routing information for the subscriber based on the subscriber identification information and the triggering identification information. Here, the service key refers to an identification information defining the additional service to be accompanied by the specified triggering information.

In the case that the called party is a subscriber of the substitute ringback tone service, the service key indicates the substitute ringback tone service and the routing information corresponds to the routing information to the playing server 140.

Subsequently, the terminating switch 120 transmits a service request including the triggering identification information, the routing information of the playing server 140, the WO 2004/073334 PCT/KR2003/002497 called party identification information to the SCP 122 while suspending the call process to the called party.

Receiving the service request from the terminating switch 120, the SCP 122 determines whether the service key included in the request corresponds to the substitute ringback tone service. If the service key corresponds to the substitute ringback tone service, the SCP 122 transmits, to the terminating switch 120, an initial call setup preparation message including the called party identification information and the routing information to the playing server 140 (step 214).

When receiving initial call setup preparation message, the terminating switch 120 transmits its function specification information the CAMEL functionality information defined in the CAMEL) (step 216). When the function specification information is received, the SCP 122 determines whether the terminating switch 122 can perform the function of generating and controlling a call to the playing server 140. When the terminating switch 122 is determined to have such a capability, the SCP 122 requests the terminating switch 120 to generate a call to the playing server 120 (Step 218).

In the case that the message received from the SCP 122 in the step 218 dictates a call process to the playing server 140, the terminating switch 120 transmits, to the playing server 140, the Initial Address Message (IAM) including the called pary identification information and the routing information to the playing server (step 220). When the Initial Address Message (IAM) is received from the terminating switch 120, the playing server 140 transmits an Address Completion Message (ACM) to the terminating switch 120 (step 222).

WO 2004/073334 PCT/KR2003/002497 16 When receiving the Address Completion Message (ACM) from the playing server 140, the terminating switch 120 transmits another Address Completion Message (ACM) corresponding to the received ACM to the originating switch 110 (step 224). On the other hand, just after transmitting the ACM in the step 222, the playing server 140 transmits a sound information query message including the called party identification information the MIN of the called party) acquired in the step 220 to the sound information server 130.

When the sound information server 130 receives the sound information query message, the sound information server 130 provides the sound information the sound name or the sound code designated by the subscriber) corresponding to the identification information of the called party the MIN of the called party) to the playing server 140 (step 228).

Upon receiving the sound information from the sound information server 130, the playing server 140 reads the sound data corresponding to the sound information, plays the sound data, and transmits the sound to the terminating switch 120. The terminating switch 120 relays the sound to the called party through the originating switch 110 (step 230).

Afterwards, the SCP 122 requests, to the terminating switch 120, to set up a answering trigger detection point (DP15) for detecting the generation of the answering event in the terminal corresponding to the called party identification information the MIN of the called party) (step 232). The terminating switch 120 receiving the request sets the answering trigger detection point (DP 15) so as to detect the answering event message from the terminal corresponding to the called party identification information (step 234).

The SCP 122 request that the terminating switch 120 continues the call process to the terminal corresponding to the called party identification information in the step 234.

WO 2004/073334 PCT/KR2003/002497 17 By this request, the terminating switch 120 proceeds a series of process, continueing the call process corresponding to the called party identification information, and the terminating switch 120 carries out phasing to the terminal of the called party in this process (step 236).

Next, the steps of answering by the called party (steps 238 through 252) are described.

If the called party answers the call during the play of the substitute ringback tone, the terminating switch 120 identifies the teminating terminal by the called party identification information included the answering event message. Subsequently, the terminating switch 120 detects the answering trigger detection point (DP 15: T_Answer) for the terminating terminal in the Basic Call State Model (T BCSM), and generates a answering trigger to send a service request including the triggerring identification information corresponding to the answering trigger (step 242).

If the triggering identification information received in the step 242 corresponds to the answering trigger, the terminating switch 120 releases the call to the playing server 140 and requests a connection of the call to the subscriber (step 244). The terminating switch 120 receiving the request transmits an ISUP call release request (REL) to the playing server 140 and carries out a series of the call release process before setting up a terminating call to the subscriber corresponding to the called party identification information (step 246). When the playing server 140 receives the call release request message (REL) from the terminating switch 120, the playing server 140 carries out the series of the call release process and transmits a message confirming the release of the call WO 2004/073334 PCT/KR2003/002497 18 to the terminating terminal 120 (step 248).

The terminating switch 120 transmits the response message to the originating switch 110 in step 250, and delivers conversation messages between the calling party and the called party (step 252).

FIG. 6 shows another embodiment of the mobile communications system for implementing the substitute ringback tone providing method of the present invention. In the embodiment of the FIG.6, the SCP 152 has a sound information table 154 or at least may access the tone information table 154. The SCP 152 provides sound information for each service subscriber stored in the table 154 to the playing server 160. In other words, the SCP 152 carries out a function of providing for the sound information which is carried out by the sound information server 130 in FIG.3. In such a case, a web server, a WAP server, and an ARS system for supporting the subscription and withdrawal of the service and an alteration of the sound may be included in the playing server 160 or be connected to the playing server 160. Accordingly, the playing server 160 or another server responsible for the service subscription or the alteration of the sound registers the sound information for the subscriber the sound name or the sound code designated by the subscriber) in the sound information table 154 of the SCP 152.

Referring to FIGS. 7A and 7B, when an arbitrary calling party calls the service subscriber in a state that the sound information for the subscriber is registered in the sound information table 154 of the SCP 152, steps of initial addressing and playing substitute ringback tone are carried out similarly to those shown in FIGS. 5A and 5B. Particularly, in step 226A, when the playing server 160 transmits message inquiring the sound WO 2004/073334 PCT/KR2003/002497 19 information including the called party identification information MIN of the called party) to the SCP 152, the SCP 152 transmits the sound information corresponding to the called party identification information to the playing server 130 (step 228A). Upon receiving the sound information from the SCP 52, the playing server 160 reads and plays the corresponding sound data stored in a storage to transmit the sound to the terminating switch 120. The terminating switch 120 relays the sound to the originating switch 110, and thus the substitute ringback tone is played at the originating terminal (step 230). The other steps shown in FIGS. 7A and 7B are identical to those in FIGS. 5A and 5B, and thus the description thereof is omitted.

FIG. 8 shows another embodiment of the mobile communications system for implementing the substitute ringback tone providing method of the present invention. The embodiment shown in FIG. 8 is similar to that shown in FIG. 6, except that the SCP 172 provides the sound information table 174 to the playing server 180 with the assistance of a separate agent 176. Here, the agent 176 may be a demon program executed in the SCP 172 or a separate physical server, and preferably communicates with the playing server 180 using the TCP/IP or UDP/IP. The agent 176 operates as a client for the sound information table 174. When the playing server 180 requests the sound information of the called party in the step 226A of FIG. 6, the agent 176 reads out the sound information for the called party from the sound information table 174 and provides the sound information in the step 228A. Another agent 182 which requests and receives the sound information from the agent 174 of the SCP 172 might be provided in the playing server 180 as well.

Although the present invention has been described in detail above, it should be WO 2004/073334 PCT/KR2003/002497 understood that foregoing description is illustrative and nor restrictive. For example, the playing server 140, 160, and 180 can be operated by a separate service provider other than the mobile communications carrier. Also, even though it was described, in FIG. 6 and related descriptions, that the SCP 152 is interfaced to the playing server 160 by CAP, the SCP 152 may be interfaced to the playing server 160 by a different manner.

Thus, those of ordinary skill in the art will appreciate that many obvious modifications can be made to the invention without departing from its sprit or essential characteristics. We claim all modifications and variation coming within sprit and scope of the following claims.

Industrial Applicability The present invention allows the carrier to provide the substitute ringback tone service without replacement or substantial modification of the MSC/VLR and reduce the relevant costs. The vendor can reduce the price of the switching system since the customizing process is minimized, and the carrier can acquire the service platform using a general purpose switching system without the restriction of using specific system provided by a specific manufacturer.

Since the replacement or substantial modification of the MSC/VLR is not required, the introduction, addition, or upgrading of the playing server is simple. In case that the substitute ringback tone service is provided by a separate carrier other than the carrier, the service provider can offer the service easily and quickly.

On the other hand, in the case of embodiment of FIG. 3, the cost for the SCP is WO 2004/073334 PCT/KR2003/002497 reduced because the SCP is not connected to the IP and thus the load of the SCP is lowered considerably.

Claims (17)

1. A system for providing substitute ringback tone, comprising: a terminating switch, capable of being connected to a substitute ringback tone playing server storing a sound file designated by a subscriber, for processing each terminating call in accordance with a predetermined call state model; a service control point connected to said terminating switch for controlling the call process of said terminating switch in response to a service request from said terminating switch; and a home location register for storing service subscription information of each subscriber and information for routing to the substitute ringback tone playing server, wherein, when detecting a call attempt detection point in the call state model for the subscriber, said terminating switch suspends the call process to the subscriber and provides said service control point with a service request including the subscriber identification information, the service subscription information, and the routing information, wherein, when a predetermined service key is included in the service subscription information, said service control point provides said terminating switch with the subscriber identification information and the routing information and makes said terminating switch to be connected to the playing server using the routing information and the subscriber identification information, so that the playing server provides the substitute ringback tone designated by the subscriber to a calling party, wherein, when detecting an answering detection point in the call state model for WO 2004/073334 PCT/KR2003/002497 23 the subscriber, said terminating switch sends a service request message to said service control point based on subscriber identification information included in the answer and releases the call to the substitute ringback tone playing server and sets up a call to the subscriber under the control of said service control point, so that a call channel is set up between the calling party and the subscriber.

2. The system as claimed in claim 1, wherein said substitute ringback tone playing server acquires sound information designated by the subscriber from a predetermined substitute ringback tone information server, provides the substitute ringback tone corrresponding to the sound information to the calling party.

3. The system as claimed in claim 2, wherein said service control point provides the sound information to the substitute ringback tone playing server, so that the playing server provides the substitute ringback tone corrresponding to the sound information to the calling party.

4. The system as claimed in claim 3, futher comprising: an agent for providing the sound information stored in said service control point to the substitute ringback tone playing server in response to a request of the substitute ringback tone playing server.

A method for providing substitute ringback tone comprising the steps of: WO 2004/073334 PCTIKR2003/002497 24 providing a terminating switch capable of being connected to a substitute ringback tone playing server storing a sound file designated by a subscriber for processing each terminating call in accordance with a predetermined call state model, a service control point programmed to detect a plurality of detection points including a call attempt detection point and an answering detection point in the call state model, and connected to the terminating switch for controlling the call process of the terminating switch in response to a service request from the terminating switch; and a home location register for storing service subscription information of each subscriber and information for routing to the substitute ringback tone playing server; when detecting the call attempt detection point for the subscriber, the terminating switch's suspending the call process to the subscriber and providing the service control point with a service request including the subscriber identification information, the service subscription information, and the routing information; when a predetermined service key is included in the service subscription information, the service control point's providing of the subscriber identification information and the routing information to the terminating switch, and making the terminating switch to be connected to the playing server using the routing information and the subscriber identification information; the playing server's providing of the substitute ringback tone designated by the subscriber to a calling party; and when detecting the answering detection point, the terminating switch's sending of a service request message to the service control point based on subscriber identification WO 2004/073334 PCT/KR2003/002497 information included in the answer, releasing the call to the substitute ringback tone playing server, and setting up a call to the subscriber under the control of the service control point, so that a call channel is set up between the calling party and the subscriber.

6. The method as claimed in claim 5, wherein, in said step the substitute ringback tone playing server acquires sound information designated by the subscriber from a prefetermined substitute ringback tone information server, provides the substitute ringback tone corrresponding to the sound information to the calling party via the terminating switch.

7. The method as claimed in claim 6, wherein the terminating switch acquires the service subscription information of the subscriber and the routing information before receiving a call setup request from the calling party.

8. The method as claimed in claim 6, wherein the terminating switch acquires the service subscription information of the subscriber and the routing information from the home location register after receiving a call setup request from the calling party.

9. The method as claimed in claim 6, wherein, the said step the service control point determines whether the terminating switch has a capability of generating and controlling of a call to the substitute ringback tone playing server for carrying out the substitute ringback tone service, and provides the routing information and the subscriber WO 2004/073334 PCT/KR2003/002497 26 identification information to the terminating switch only when the terminating switch has the capacity.

The method as claimed in claim 9, further comprising a step of: the terminating switch's providing of function specification information of the terminating switch to the service control point to support the determination of the service control point.

11. The method as claimed in claim 5, wherein the service control point maintains the sound information designated by the subscriber, wherein and said step comprises the steps of: (dl) allowing the sound information stored in the service control point to the substitute ringback tone playing server; and (d2) playing the substitute ringback tone corresponding to the sound information, by the substitute ringback tone playing server, and providing the tone to the calling party via the terminating switch.

12. The method as claimed in claim 11, wherein the terminating switch acquires the service subscription information of the subscriber and the routing information before receiving a call setup request from the calling party.

13. The method as claimed in claim 11, wherein the terminating switch acquires WO 2004/073334 PCT/KR2003/002497 27 the service subscription information of the subscriber and the routing information from the home location register after receiving a call setup request from the calling party.

14. The method as claimed in claim 1 1,wherein, the said step the service control point determines whether the terminating switch has a capability of generating and controlling of a call to the substitute ringback tone playing server for carrying out the substitute ringback tone service, and provides the routing information and the subscriber identification information to the terminating switch only when the terminating switch has the capacity.

The method as claimed in claim 14, further comprising a step of: the terminating switch's providing of function specification information of the terminating switch to the service control point to support the determination of the service control point.

16. The method as claimed in claim 11, wherein the service control point directly provides sound information to the substitute ringback tone playing server in response to a request of the substitute ringback tone playing server.

17. The method as claimed in claim 11, wherein a predetermined agent capable of accessing the sound information provides the sound information to the substitute ringback tone playing server.