Abstract:
A system and method of providing an enhanced service in a telecommunications network. The system includes a telecommunications network utilizing a circuit switched and packet switched access capability. The system also includes a sending User Equipment (UE) originating a call to a receiving UE. The sending UE sends an indicator informing the network to wait for further call information before proceeding with a call request towards the receiving UE. The system also includes a control node for routing calls within the network. The control node combines the call information received from the sending UE with call routing information of the call for connecting the call with the receiving UE to form a call request to the receiving UE. Upon receiving the call request message by the receiving UE, the call is connected and a media path is established between the receiving UE and the sending UE.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to communications networks, and in particular, to communications networks that employ systems and methods for enhancing IP Multimedia Subsystem (IMS) centralized services. 
       BACKGROUND 
       [0002]    Third Generation Partnership Project 2 (3GPP2) specifications, as described in IP Multimedia System (IMS) centralized services (Release 8), 3GPP TR 23.892 specify and define IMS architecture along with a number of enablers that can be used to implement various multimedia services using packet-based bearers. In particular, TR 23.892 addresses an architecture that supports the provision of IMS based services across a variety of Packet Switched (PS) domain or Circuit Switched (CS) domain access networks. 
         [0003]    With this transition to PS domain access networks from CS domain access networks, there are several services which may not be available to users. Currently, where an IMS Centralized Services (ICS) User Equipment (UE) only has CS access, the ICS UE does not have many services available as compared to other UEs having access to PS domain access networks. A system and method are needed which provides as many services as possible to a UE with minimal modifications to a network. 
       SUMMARY 
       [0004]    The present invention provides a system and method which provides enhanced services in a telecommunications network. Thus, in one embodiment, the present invention is directed to a system which includes a telecommunications network utilizing a circuit switched and packet switched access capability. The system also includes a sending User Equipment (UE) originating a call to a receiving UE. The sending UE sends an indicator informing the network to wait for further call information before proceeding with a call request towards the receiving UE. The system also includes a control node for routing calls within the network. The control node combines the call information received from the sending UE with call routing information of the call for connecting the call with the receiving UE to form a call request to the receiving UE. Upon receiving the call request message by the receiving UE, the call is connected and a media path is established between the receiving UE and the sending UE. 
         [0005]    In another embodiment, the present invention is directed to a method of providing an Instant Picture Presentation service by utilizing CS and PS access capability. The method begins by the sending UE sending an indicator informing the network to wait for further call information before proceeding with a call request towards the receiving UE. The sending UE then initiates a call with the receiving UE. The call is then routed within the network. Responsive to the routing of the call, a call request is sent to a control node within the telecommunications network. Call information is sent by the sending UE to the control node. The control node then combines the call information with the call routing information to form a call request message for connecting the call with the receiving UE. The call request message is then sent to the receiving UE. The call is connected between the receiving UE and the sending UE. A media path is established between the receiving UE and the sending UE. 
         [0006]    In still another embodiment, the present invention is directed to a node within a telecommunications network utilizing circuit switched and packet switched access capability to provide an enhanced service. The node is capable of receiving an indicator from a sending UE originating a call to a receiving UE. The indicator informs the network to wait for further call information before proceeding with a call request towards the receiving UE. The node combines the call information with call routing information to form a call request to the receiving UE. The node sends the call request message upon receiving both the call information and call routing information. 
         [0007]    In another embodiment, the present invention is directed to a system and method providing Customized Alert Tone (CAT) service to a receiving UE from a sending UE in a telecommunications network. The method begins with the sending UE initiating a call to the receiving UE. The call is routed through a control node. Next, the control node establishes a Session Initiated Protocol (SIP) session with a Media Resource Function (MRF). The CAT service is then performed from the MRF to the sending UE. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  (prior art) illustrates an existing telecommunications network; 
           [0009]      FIG. 2  is a signaling diagram illustrating an exemplary call flow for a Customized Alerting Tone (CAT) service in one embodiment of the present invention; 
           [0010]      FIGS. 3A-3D  are flow charts illustrating the steps for executing a call utilizing a CAT service according to the teachings of the present invention; 
           [0011]      FIG. 4  is a signaling diagram illustrating the service of Instant Picture Presentation by utilizing CS and PS access capability in an embodiment of the present invention; and 
           [0012]      FIGS. 5A-5D  are flow charts illustrating the steps for executing a call utilizing a Instant Picture Presentation by utilizing CS and PS access capability according to the teachings of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The present invention is a system and method of enhancing IMS centralized services.  FIG. 1  illustrates an existing telecommunications network  10 . An ICS UE  12  communicates with a Mobile Switching Center Server (MSC-S)  14 . The MSC-S having a Media Gateway Control Function (MGCF)  18  utilizes a Media Gateway (MGW)  16  to communicate within the telecommunications network. The network includes a Home Subscriber Server (HSS)  20 . An IMS CS Control Function (ICCF)  22  provides functions necessary for provision of IMS services for calls originated or terminated over CS access networks and for calls transferred between CS and PS access networks. The telecommunications network also includes a Serving Call Service Control Function (S-CSCF)  24 . The network may also include a Customized Alert Tone (CAT) Access Stratum (AS)  26  having a Media Resource Function (MRF)  28 . An SSMF  30  (Session Split Merger Function—controls whether one session has to be split into two or whether two sessions have to be merged into one) may also be utilized in the network. In the scenarios described below, the ICS UE  12  calls a UE B  32 . 
         [0014]      FIG. 2  is a signaling diagram illustrating an exemplary call flow for a Customized Alerting Tone (CAT) service in one embodiment of the present invention. In  100 , the ICS UE  12  initiates a normal CS call setup for the UE B  32  towards the MSC-S  14 . The ICS UE only has CS access. Next, in  102 , the MSC-S sends a Customized Application for Mobile network Enhanced Logic (CAMEL) or CAMEL Application Part (CAP) initial Dial Pulse (DP) message, which originates a trigger request, to the ICCF  22  to retrieve an ICS Call initiation Result (IMRN) for the ICCF  22 . In  104 , the ICCF  22  returns an IMRN to the MSC-S  14 . In  106 , the MSC-S routes the call to the MGCF  18  by sending an Initial Address Message (IAM). The MGCF  18  then sends a Session Initiated Protocol (SIP) INVITE message to the ICCF  22  by Packet Signaling Information (PSI) routing in  108 . In  110 , the ICCF sends a SIP INVITE message towards the S-CSCF  24  serving the UE B  32 . Next, as the UE B  32  is a CAT subscriber, the S-CSCF  24  forwards the message to the CAT AS  26  via an iFC (initial Filter Criteria; downloaded from the HSS, includes a list of application servers to be invoked) checking in  112 . When the UE B phone starts ringing, a SIP  180  ringing is sent to the CAT AS  26 . The CAT AS initiates a session with the MRF  28  requesting the MRF to generate the CAT for the ICS UE, according to a CAT procedure. Next, in  114 , the CAT AS  26 /MRF  26  inserts a P-early-media and forwards the SIP  180  ringing message from the UE B to the ICCF  22  via the S-CSCF  24 . In  116 , the ICCF  22  forwards the SIP  180  ringing message to the MGCF  18 . The MGCF  18  and MGW  16  do not generate local ring-back tone towards the ICS UE  12 . The MGCF  18  sends an Address Complete Message (ACM) to the MSC-S  14  at  118 . In  120 , the MSC-S sends an Alerting message to the ICS UE  12 . The customized CAT is then played from the MRF  26  to the ICS UE  12  at  122 . 
         [0015]    When the CAT AS receives a SIP  200  OK message from UE B (not shown), the MRF  28  is informed to stop playing the CAT. The CAT AS  26  then forwards the SIP  200  OK message to the ICCF  22  through the S-CSCF  24  at  124 . At  126 , the ICCF sends the SIP  200  OK message to the MGCF  18 . The MGCF  18  then sends an ANM (answer indication) to the MSC-S  14  at  128 . The MSC-S then sends a Connect message to the ICS UE  12  at  130 . In  132 , the MGCF  18  sends a SIP ACK message to the ICCF  22 . In  134 , the ICCF  22  sends a SIP ACK message towards the UE B via the S-CSCF  24 . The media is then established e2e (end to end) at  136 . The present invention, as depicted in  FIG. 2 , supports customized alerting tone service without modifying the UE or the network. 
         [0016]      FIGS. 3A-3D  are flow charts illustrating the steps for executing a call utilizing a CAT service according to the teachings of the present invention. With reference to  FIGS. 1-3 , the method of the present invention will now be explained. The method begins in step  200  where the ICS UE  12  initiates a normal CS call setup for the UE B  32  towards the MSC-S  14 . The ICS UE only has CS access. Next, in step  202 , the MSC-S sends a CAT initial DP message, which originates a trigger request, to the ICCF  22  to retrieve an ICS Call initiation Result (IMRN) for the ICCF  22 . In step  204 , the ICCF  22  returns an IMRN to the MSC-S  14 . In step  206 , the MSC-S routes the call to the MGCF  18  by sending an Initial Address Message (IAM) to the MGCF  18 . Next, in step  208 , the MGCF  18  sends a Session Initiated Protocol (SIP) INVITE message to the ICCF  22 . In turn, in step  210 , the ICCF sends a SIP INVITE message towards the S-CSCF  24  serving the UE B  32 . In step  212 , the S-CSCF  24  forwards the message to the CAT AS  26 . When the UE B phone rings, a SIP  180  ringing is sent to the CAT AS  26 . In step  214 , the CAT AS initiates a session with the MRF  28  requesting the MRF to generate the CAT for the ICS UE. 
         [0017]    In step  216 , the CAT AS  26 /MRF  26  forwards the SIP  180  ringing message from the UE B to the ICCF  22  via the S-CSCF  24 . In  218 , the ICCF  22  forwards the SIP  180  ringing message to the MGCF  18 . The MGCF  18  and MGW  16  do not generate local ring-back tone towards the ICS UE  12 . Next, in step  220 , the MGCF  18  sends an ACM to the MSC-S  14 . In step  222 , the MSC-S sends an Alerting message to the ICS UE  12 . Next, the customized CAT is played from the MRF  26  to the ICS UE  12  at step  224 . 
         [0018]    In step  226 , when the CAT AS receives a SIP  200  OK message from the UE B (not shown), the MRF  28  is informed to stop playing the CAT. In step  228 , the CAT AS  26  forwards the SIP  200  OK message to the ICCF  22  through the S-CSCF  24 . In step  230 , the ICCF sends the SIP  200  OK message to the MGCF  18 . The MGCF  18  then sends an ANM to the MSC-S  14  at step  232 . In step  234 , the MSC-S sends a Connect message to the ICS UE  12 . Next, in step  236 , the MGCF  18  sends a SIP ACK message to the ICCF  22 . The ICCF  22  then sends a SIP ACK message towards the UE B via the S-CSCF  24  at step  238 . The media is then established e2e at step  240 . 
         [0019]    In another embodiment of the present invention, when a PS access (with a limited capability) network is available for the ICS UE, the ICS UE may provide enhanced service to the user by combining CS and PS access together.  FIG. 4  is a signaling diagram illustrating the service of Instant Picture Presentation by utilizing CS and PS access capability in an embodiment of the present invention. When an ICS UE  12  desires to initiate a call with an instant picture presentation, in  300 , the ICS UE first sends an indication via the Unstructured Supplemental Service Data (USSD) (not shown) to the ICCF  22  informing the network to wait for Call-info in a SIP session before proceeding with an ICS call request towards the UE B  32 . Since the ICS UE is initiating the ICS call request and the SIP session, it can give the network information in the indication about the upcoming ICS call request and SIP session, which may be used by the network for the identification and correlation of the requests. Next, in  302 , the ICS UE  12  initiates a normal CS call towards the MSC-S  14 . In  304 , the MSC-S sends a CAMEL originating trigger request to the ICCF to retrieve an IMRN for the ICCF. Next, the ICCF returns an IMRN to the MSC-S at  306 . In  308 , the MSC-S  14  routes the call to the MGCF  18 . Next, in  310 , the MGCF sends a SIP INVITE message to the ICCF by PSI routing. Based on the “wait” indication received in  300 , the ICCF  22  includes a tag in the SIP INVITE message and forwards it to the SSMF  30  in  312 . The SSMF then holds the processing of the ICS call request according to the tag. 
         [0020]    Next, in  314 , the ICS UE  12  sends a SIP INVITE message which includes Call-Info. This INVITE message adds an icon to the session which has already been established in step 2 over the PS network to the SSMF  30 . The SSMF may then correlate this SIP session with the on-hold ICS call request. In  316 , the SSMF combines the two requests and forms a new SIP INVITE message including the Call-info on icon and sends the message to the UE B  32  via the S-CSCF  24 . Next, the UE B  32  sends a SIP  180  Ringing message to the SSMF  30  in  318 . The SSMF, at  320 , then sends the SIP  180  Ringing message to the ICCF  22 . In  322 , the ICCF sends the SIP  180  Ringing message to the MGCF  18 . The MGCF sends an ACM to the MSC-S  14  at  324 . At  326 , the MSC-S sends an Alerting message to the ICS UE  12 . At  328 , the UEB sends a SIP  200  OK message to the SSMF  30  via the S-CSCF  24 . Next, in  330 , the SSMF sends the SIP  200  OK message to the ICCF  22 . In  332 , the ICCF sends the SIP  200  OK message to the MGCF  18 . In addition, at  334 , the SSMF sends an SIP  200  OK message to the ICS UE  12 . At  336 , the MGCF  18  sends an ANM to the MSC-S  14 . The MSC-S then sends a Connect message to the ICS UE  12  at  338 . At  340 , the MGCF sends an SIP ACK message to the ICCF  22 . The ICCF sends an SIP ACK message to the SSMF  30  at  342 . At  344 , the SSMF sends the SIP ACK message to the UE-B via the S-CSCF  24 . At  346 , the media path is established e2e. 
         [0021]    In the embodiment described in  FIG. 4 , the enhancement is the USSD capability to express the “wait” indication. This enhancement provides additional services without large modifications to the network. It should be understood that the Instant Picture Presentation Service is exemplary only as the present invention may be utilized to provide other enhanced services besides the Instant Picture Presentation Service to users; e.g., adding a business card. 
         [0022]      FIGS. 5A-5D  are flow charts illustrating the steps for executing a call utilizing a Instant Picture Presentation by utilizing CS and PS access capability according to the teachings of the present invention. With reference to  FIGS. 1 ,  4  and  5 , the method of the present invention will now be explained. The method begins with step  400  where, an ICS UE  12  desiring to initiate a call with an instant picture presentation first sends an indication via the USSD (not shown) to the ICCF  22  informing the network to wait for Call-info in a SIP session before proceeding with an ICS call request towards the UE B  32 . Since the ICS UE is initiating the ICS call request and the SIP session, it can give the network information in the indication about the upcoming ICS call request and SIP session, which may be used by the network for the identification and correlation of the requests. Next, in step  402 , the ICS UE  12  initiates a normal CS call towards the MSC-S  14 . In step  404 , the MSC-S sends a CAMEL originating trigger request to the ICCF to retrieve an IMRN for the ICCF. Next, in step  406 , the ICCF returns an IMRN to the MSC-S. In step  408 , the call is routed to the MGCF  18 . The MGCF then sends a SIP INVITE message to the ICCF by PSI routing in step  410 . Based on the “wait” indication received in step  400 , the ICCF  22  includes a tag in the SIP INVITE message and forwards it to the SSMF  30  in step  412 . The SSMF then holds the processing of the ICS call request according to the tag. 
         [0023]    Next, in step  414 , a SIP INVITE message is sent from the ICS UE  12 . The message includes Call-Info with purpose=icon over the PS network to the SSMF  30 . The SSMF correlates this SIP session with the held ICS call request in step  416 . Next, in step  418 , the SSMF combines the two requests and forms a new SIP INVITE message including the Call-info on icon and sends the message to the UE B  32  via the S-CSCF  24 . In step  420 , the UE B  32  sends a SIP  180  Ringing message to the SSMF  30 . The SSMF, at step  422 , then sends the SIP  180  Ringing message to the ICCF  22 . In step  424 , the ICCF sends the SIP  180  Ringing message to the MGCF  18 . At step  426 , the MGCF sends an ACM to the MSC-S  14 . Next, at step  428 , the MSC-S sends an Alerting message to the ICS UE  12 . At step  430 , the UE B sends a SIP  200  OK message to the SSMF  30  via the S-CSCF  24 . Next, in step  432 , the SSMF sends the SIP  200  OK message to the ICCF  22 . In step  434 , the ICCF sends the SIP  200  OK message to the MGCF  18 . In addition, at step  436 , the SSMF sends an SIP  200  OK message to the ICS UE  12 . At  438 , the MGCF  18  sends an ANM to the MSC-S  14 . The MSC-S then sends a Connect message to the ICS UE  12  at step  440 . Nest, in step  442 , the MGCF sends an SIP ACK message to the ICCF  22 , which forwards it to the SSMF  30  and the UE-B via the S-CSCF  24 . In step  444 , the media path is established e2e. 
         [0024]    The present invention may provide more services to users without significant modification to the ICS architecture. The present invention may be utilized with or without limited PS access together with CS access using the I1-cs option. 
         [0025]    The present invention may of course be carried out in other specific ways than those herein set forth without departing from the essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.