Abstract:
Intelligent network service (“IN service”) may be invoked beyond initial call setup for additional call management by establishing trigger detection points that refer the call back to a service control point. Subsequent requests for IN service with respect to a particular call may be correlated with a previous request for IN service by providing correlation information to the service control point. Once correlated, information from both the earlier and later IN service requests are available to the service control point.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention described and claimed here concerns intelligent networks and call processing. Such networks are described in U.S. Pat. No. 6,101,250 and No. 6,947,541, incorporated here by reference. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  is a block diagram of a telecommunications system; 
           [0003]      FIG. 2  is a call flow diagram; 
           [0004]      FIG. 3  is a call flow diagram for a procedure for completing a call to voice mail over an optimized route for a subscriber roaming in another country; 
           [0005]      FIGS. 4 and 5  are block diagrams of a telecommunications system illustrating the routing of a call to voice mail shown in the call flow diagram of  FIG. 3 ; 
           [0006]      FIG. 6  is a call flow diagram for a procedure for completing a call to voice mail over an optimized route for a subscriber roaming in an area served by a switch operated by another carrier; 
           [0007]      FIGS. 7 and 8  are block diagrams of a telecommunications system illustrating the routing of a call to voice mail shown in the call flow diagram of  FIG. 6 . 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0008]    A telecommunications system serving a calling party  10  is shown in  FIG. 1 . The calling party  10 , which may be identified by its calling line identity (CLI), initiates a call to a called party  12 , entering the system via a gateway such as a service switching point (SSP)  20 . The called party  12  may be identified and reached through the telecommunications system by a called subscriber number (CSN). 
         [0009]    As shown in the associated call flow diagram of  FIG. 2 , the call encounters a previously-established first trigger detection point (TDP) at the SSP  20 . The SSP  20  then queries a service control point (SCP)  30 , providing information that may include the identities of the calling party (e.g., the CLI) and the called party  12  (e.g., the CSN) and invoking intelligent network service (“IN service”) as dictated by the specific trigger detection point. In response, the SCP  30  then issues instructions, such as call-processing instructions, to the SSP  20 . In an alternative configuration, the SSP  20  and the SCP  30  may be realized collectively as an intelligent network service node. 
         [0010]    In certain instances, it may be advantageous for the ongoing call to subsequently invoke the same IN service that was enabled following a previous encounter of a trigger detection point. This may be accomplished by establishing one or more additional trigger detection points. As the call proceeds, should the call trigger these additional trigger detection points, the SSP  20  again queries the SCP  30 , invoking the same IN service. 
         [0011]    A second trigger detection point encounter is shown in the fifth segment in  FIG. 2 . When querying the SCP  30  this additional time, the SSP  20  forwards information that enables the SCP  30  to correlate this second IN dialog with the previous one (see the bracket on the right-hand side in  FIG. 2 ). Otherwise, the SCP  30  would treat the second request for IN service as a new, independent call. The correlation information may be an identifier assigned to the call, such as the identity of the original calling party (i.e., the CLI), typically preserved in the messaging for the duration of the call. Also, the SSP  20  may forward new or additional information to the SCP  30 , as well as the identity of the specific trigger encountered. 
         [0012]    Once the current and prior requests for IN service have been correlated, the SCP  30  can access the content of both of the dialogs, e.g., data and parameters such as the CLI, the CSN, routing, and other telephone numbers. Next, the SCP  30  provides further call processing instructions to the SSP  20 , based on the information received at the SCP  30 , or a combination of information gathered from other SSP-SCP interactions that follow trigger detection point encounters. 
         [0013]    In the call flow diagram of  FIG. 2 , the horizontal lines representing the execution of the call are shown terminating at a dashed vertical line to representing a non-specific destination, such as a called party  12 . Similarly, the origin of the call segment resulting in a trigger detection originates at the vertical dashed line—a non-specific destination, such as the called party  12  or perhaps another switch. The final execution of call instructions is shown as a dashed line to indicate that the instructions include a scenario where a call is not completed. 
         [0014]    The foregoing procedure may be used to optimize routing for a call ultimately routed to voice mail. In this example, illustrated in  FIGS. 3-5 , the called party  12  is a wireless customer, normally physically present in the same country as that of the calling party  10 , but now temporarily traveling in another country. 
         [0015]    For the purpose of discussion, some of the designations of components and signaling employed are those associated with SS7 switching and GSM networks. For example, the SSP  20  is realized in  FIGS. 4 and 5  as a combined mobile switching center (MSC) and SSP (MSC/SSP  22 ). Nevertheless, the concepts described may be applied to other switching conventions and communication modes and formats. Further, for clarity of presentation, not all of the signaling that normally accompanies the call processing discussed here is shown in the drawings or described here, but is understood to occur nevertheless as required by the protocols and procedures employed. 
         [0016]    During initial call set up, the calling party  10  seeks to contact the called party  12  based on the latter&#39;s mobile subscriber&#39;s telephone number (the CSN). In accord with currently-employed protocols for a network of mobile subscribers, the MSC/SSP  20  queries a home location register (HLR)  50  associated with the MSC/SSP  22  to determine the status and location of the called party  12 . 
         [0017]    Since the called party  12  is roaming in a network in another country, the HLR  50  responds with a routing number such as an international routing number (IRN) for the called party, which supplants the CSN. The international routing number (IRN) is used to route the call to another mobile switching center—the visited MSC  60 , located in the network where the called party  12  is now registered, and ultimately to the called party  12 . When the mobile subscriber, i.e., the called party  12 , initially registered with the visited MSC  60 , the particulars associated with that subscriber, such as the CSN, were entered in a visitor location register (VLR)  70  associated with the visited MSC  60 . 
         [0018]    Using the international routing number (IRN) of the called party  12 , the MSC/SSP  22  then initiates the call, encountering a trigger detection point responsive to international routing numbers and commencing a first dialog with the SCP  30  ( FIG. 3 ). The MSC/SSP  22  queries the SCP  30 , passing the calling party&#39;s CLI and the called party&#39;s IRN to the SCP  30 . 
         [0019]    The SCP  30  responds with call processing instructions, directing the MSC/SSP  22  to proceed with the call and begin setting up an outbound international call leg  80 . Also, the SCP  30  directs the MSC/SSP  22  to arm an event detection point (EDP) for a “busy” condition. As discussed below, this will enable the MSC/SSP  22  to maintain the original call leg from the calling party  10 . 
         [0020]    Should the called party  12  not answer, after a predetermined period of time the visited MSC  60  will forward the call, i.e., redirect the call, to the called party&#39;s home network (MSC/SSP  22 ) over a return international call leg  82 . Since the forwarded call is returning to the called party&#39;s home network, it now contains the called party&#39;s number—the CSN (recovered from the visited MSC  60 ), as well as the number for voice mail as the destination, arbitrarily designated here as the “forward to number” (FTN, e.g., the voice mail group number). (Although  FIGS. 4 and 5  show the return call leg  82  connected to the same MSC/SSP  22  as the outbound call leg  80 , this is only for purposes of clarity. The domestic side of the network typically has multiple switches and therefore the return call leg  82  would likely connect to a different MSC/SSP. Consequently, the MSC/SSP  22  in these figures should be understood to represent multiple switches and are indicated in the plural in the drawings: “SSPs” in  FIGS. 1 and 2  and MSC/SSPs in  FIGS. 3-8 .) If the forwarded call was allowed to go to completion (via a third call leg  84 —shown dashed in FIG.  4 —from the MSC/SSP  22  to voice mail service  90 ), the called party  12  would incur charges for the two international call legs  80  and  82  along with an international roaming fee. Instead, call completion is suspended when the forwarded call encounters a trigger detection point at the MSC/SSP  22  (triggering, e.g., on the voice mail group number), commencing a second dialog between the MSC/SSP  22  and SCP  30 . 
         [0021]    The MSC/SSP  22  queries the SCP  30 , again invoking the intelligent network service, providing the SCP  30  with the voice mail group number (the FTN), the calling party&#39;s CLI, and the called party&#39;s CSN. Previously not available to the MSC/SSP  22  after the call was first initiated since the HLR  50  replaced it with the international routing number (IRN), the CSN was extracted from the call forwarded by the visited MSC  60 . 
         [0022]    Utilizing the calling party&#39;s CLI, the SCP  30  then correlates this second dialog with the first. In this second dialog, the SCP  30  instructs the MSC/SSP  22  to tear down (i.e., release with reason “busy”) the two international call legs  82  (the return) and  80 , back to the MSC/SSP  22 . The process of tearing down the international call legs encounters the previously-armed event detection point at the MSC/SSP  22 , suspending further call processing, leaving the circuit from the calling party  10  to the MSC/SSP  22  intact and relinquishing the second dialog (note dashed lines  80  and  82  in  FIG. 5 ). Since no voice circuits were completed (i.e., prior to an answer condition), no charges are incurred for setting up the outbound and return call legs  80  and  82 . 
         [0023]    The SCP  30  now resumes the first dialog, instructing the MSC/SSP  22  to the route the call directly to the voice mail service  90  on call leg  84 , providing the MSC/SSP  22  with the voice mail group number (the FTN) as the destination and the called party&#39;s number (the CSN) used to identify the specific subscriber&#39;s voice mail box within the voice mail service  90 . 
         [0024]    The foregoing procedure may also be used to avoid roaming charges that are incurred within the same country. For example, a wireless provider may offer service within a relatively small geographical area, perhaps within a single state. Should one of provider&#39;s subscriber be roaming in an area served by another carrier, an unanswered call to the subscriber would be forwarded to voice mail. Although there would be no charges for international call legs, the subscriber would incur roaming charges and perhaps long distance charges as well. 
         [0025]    To avoid such roaming and long distance charges, the provider could establish trigger detection points that invoke intelligent network service and prevent call completion through the remote switch ( FIGS. 6-8 ). One possible trigger could be the subscriber&#39;s remote routing number (RRN). When the call to the voice mail group number is received from a remote switch operated by the other carrier, i.e., the visited MSC, the second dialog would be invoked. As with the international case, the call legs back to the visited MSC ( 82 ′) and then back to the original MSC/SSP ( 80 ′) would be torn down. Finally, the call would be routed directly from the MSC/SSP to voice mail service.