Abstract:
A system and method for providing Call Forwarding/Multi-Destination Call Redirection services that include notifying the subscriber/owner of a call leg creation failure and taking corrective action to prevent future failures. The failure can be detected at a Far End network node and communicated to a Detection node which communicates with a Resolver node for taking corrective action.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a system and method for providing call redirection and/or multi call destination services and more particularly to a system and method for providing suitable actions based on call leg creation failures occurring during these service operations.  
         [0002]     While the invention is particularly directed to the art of telecommunications networks including wireless and wireline networks as well as packet data networks, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications including .  
         [0003]     Today, when a user registers a number for call forwarding, also known as call redirection, or as part of a multi destination call with the network, such as a registration of a Call Forwarding Forward-To Number (FTN), the network may not validate whether the number used for the redirection is a valid destination. If the number used for redirection turns out to be bad, such as a disconnected number, there is no automated mechanism to correct the problem to prevent further occurrences. There is also no automated mechanism to notify the served user, that is the user who registered the bad number, of the error. Consequently, this problem will persist for this user until perhaps he is notified by a person who has tried unsuccessfully to communicate with him in this manner.  
         [0004]     The context for bad numbers for call redirection and/or multi call destination calls includes not only call forwarding, but also such services as Flexible Alerting, Simultaneous Ringing, Multi-Line Hunt Group, Sequential Ringing, and Series Completion Service. For all of these services, the served user may provision one or more destination numbers and is not involved at invocation time and thus cannot receive immediate notification when a destination number is bad.  
         [0005]     The present invention contemplates a new and improved system and method that resolves the above-referenced difficulties and others.  
       SUMMARY OF THE INVENTION  
       [0006]     A system and method for providing Call Redirection and/or Multi Call Destination services that can include performing a corrective Action and/or notifying the subscriber/owner of a call leg creation failure and providing them further information which can include the reason for the failure.  
         [0007]     In one aspect of the invention, the method includes determining that a Call Redirection/Multi Call Destination (CR/MCD) call leg for a subscriber cannot be established at a Far End switch, sending one or more messages from the Far End Switch to a Detector indicating that the CR/MCD call leg cannot be established and the reason the CR/MCD cannot be established, and performing an Action based on the failure to establish the CR/MCD call leg.  
         [0008]     In another aspect of the invention the system includes a Far End switch including means for determining that a CR/MCD call leg for a subscriber cannot be established and means for communicating with a Network Element that the CR/MCD call leg cannot be established and the reason the CR/MCD call leg cannot be established, a Detector located remotely from the Far End Switch including means for communicating with the Far End switch to determine that the CR/MCD call leg cannot be established and the reason that the CR/MCD call leg cannot be established and means for notifying a network element that a CR/MCD call leg for the subscriber cannot be established, and a Resolving Network Element including means for communicating with the Detector for determining that CR/MCD call leg cannot be established and the reason that the CR/MCD call leg cannot be established and means for performing an Action based on the failure to establish the CR/MCD call leg.  
         [0009]     Further scope of the applicability of the present invention will become apparent from the detailed description provided below. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention exists in the construction, arrangement, and combination of the various parts of the device, and steps of the method, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in the claims, and illustrated in the accompanying drawings in which:  
         [0011]      FIG. 1  is a block diagram illustrating a system for handling call redirection/multi call destination (CR/MCD) failures in accordance with the invention;  
         [0012]      FIG. 2  is a flow chart illustrating a method for handling call redirection/multi call destination (CR/MCD) failures in accordance with the invention;  
         [0013]      FIG. 3  is a block diagram illustrating an example of a CDMA system for handling Call Redirection failures in accordance with the invention;  
         [0014]      FIG. 4  is a call flow diagram illustrating the messaging provided by the system illustrated in  FIG. 3  for Call Redirection;  
         [0015]      FIG. 5  is a call flow diagram illustrating the messaging provided by the system illustrated in  FIG. 3  for Flexible Alerting;  
         [0016]      FIG. 6  is a block diagram illustrating an example of an IMS system for handling Call Redirection failures in accordance with the invention; and  
         [0017]      FIG. 7  is a call flow diagram illustrating the messaging provided by the system illustrated in  FIG. 3  for Call Redirection.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     Referring now to the drawings wherein the showings are for purposes of illustrating the preferred embodiments of the invention only and not for purposes of limiting same. In  FIG. 1 , a system shown generally at  10 , for performing Call Redirection and/or Multi Call Destination (CR/MCD) call services in a communications network for voice calls made by a calling party A to a called party B which are forwarded or redirected to one or more parties C, D, E, etc. CR/MCD calls as pertaining the invention described herein, can include services including, but are not limited to, call forwarding, call redirection, flexible alerting, simultaneous ringing, and multi-line hunt groups, among others.  
         [0019]     For the examples provided herein, party B, for which calls are being forwarded or redirected, can be referred to as a subscriber, such as a subscriber to the CR/MCD services described herein, or the owner of such data that may be required to perform these services. The system  10  includes network elements of suitable construction using suitable protocols so as to be applicable to cellular telecommunications networks, landline telecommunications networks, circuit switched communications networks, packet-based communications networks, Internet Protocol (IP) communications networks such as those suitable for Voice Over Internet Protocol (VOIP) calls, and Internet Protocol Multimedia Subsystem (IMS) communications networks.  FIG. 2  illustrates the general method of operation, as shown generally at  200 , of the system  10  described herein.  
         [0020]     The system  10  includes a Detector  12  for detecting a failure in the establishment of a CR/MCD call leg  13 , also referred to as a CR/MCD call leg creation failure, during a CR/MCD operation as shown at step  202 . If this failure is not detected, normal call processing occurs at  204 . An example of a CR/MCD call leg includes the call leg to the forwarded or redirected destination, as represented herein by C. C can be a phone, landline or mobile terminal, or other apparatus for receiving calls such as a VOIP capable device, etc. The Detector  12  can also determine the reason for the failure, such as for example, the forwarded/redirected destination number is out of service or disconnected, or this number has been changed, or the CR/MCD information includes a vacant code or unassigned number, etc. The Detector  12  can be a switch, a Mobile Switching Center (MSC), an Application Server (AS), or some combination thereof, among others.  
         [0021]     The system  10  can also include a Far End Switch  18  responsible for establishing the CR/MCD call leg  13  to the forwarded/redirected destination, C in most of the examples provided herein. The Far End Switch  18  typically establishes the CR/MCD call leg to a local destination, or a destination assigned to the switch, such as C&#39;s phone.  
         [0022]     The Far End Switch  18  includes means for determining that the CR/MCD call leg  13  cannot be established, that is to say that the CR/MCD call leg creation has failed. The Far End Switch  18  also includes means for communicating to the Detector  12  at  14  that the CR/MCD call leg cannot be established as shown at step  206 . The Far End Switch  18 , can also include means for communicating to the Detector  12  at  16  the cause or the reason that the CR/MCD call leg cannot be established as shown at step  208 . These communications  14  and  16  can be provided using SIP or ISUP signaling, or other known protocols employing new commands or fields, etc. for providing this information. It should be appreciated that the separate messages shown at  206  and  208  can be a single message.  
         [0023]     The Detector  12  includes means for determining that the CR/MCD call leg  13  cannot be established, that is that CR/MCD call leg creation failed, which can include means for communicating with the Far End Switch  18  for receiving this information. The Detector  12  can also include means for determining the reason that the CR/MCD call leg creation failed, which can include means for communicating with the Far End Switch  18  for receiving this information provided as described above.  
         [0024]     The system  10  also includes a Resolving Network Element (RNE)  20  having means for performing one or more Actions, shown generally at  22 , based on the failure to establish the CR/MCD call leg. As described in further detail in the examples provided herein, the Action  22  can include notifying the subscriber of the failure to establish the CR/MCD call leg and the reason for the failure as shown at step  210 . The notification can include sending a message over one or more media to the subscriber B, also referred to as the owner B, to alert them of the redirection error. One example of such as message can include sending an SMS message and/or email informing B that their CR/MCD number, that is the number used to redirect their calls to C, is bad. Other examples of notifications include sending a SIP MESSAGE directly to a SIP-enabled user entity (device), leaving a message in a voice mail, sending an instant message, sending notification to web portal or other set of application servers.  
         [0025]     The Action  22  performed by the RNE  20  based on the failure to establish the CR/MCD call leg can also include deactivating the bad CR/MCD number to cease initiating future CR/MCD call legs to the affected destination as shown at  212 . The Action  22  can take place after one CR/MCD call leg failure or after reaching a threshold including a predetermined number of failures to the same destination, that of C in the examples provided. The RNE  20  can be a Home Location Register (HLR) in a wireless telecommunications network, a Service Control Point (SCP), an Application Server, or a Switch, such as a switch in a wireline telecommunications network.  
         [0026]     It should be appreciated that the Detector  12  and RNE  20  can be the same network element as shown by the dashed line  12 / 20 . Alternatively, the Detector  12  and RNE  20  can be different network elements, and if different elements, the system  10  also includes means for communicating between the Detector  12  and the RNE  20 , for informing the RNE of the CR/MCD call leg creation failure as shown at  24  and means for communicating between the Detector and the RNE for providing the RNE information needed to take the Actions described herein as shown at  26 . This information can include an identification of the subscriber B and the failed CR/MCD number, the number for reaching C, and the cause or reason for the failure.  
         [0027]      FIG. 3  shows an example of the system  10  described above, which is shown generally at  310 , that includes CDMA wireless telecommunications network elements as part of a wireless network for performing Call Forwarding in accordance with the invention.  FIG. 4  illustrates the call flow messaging sent between the network elements of  FIG. 3  for this Call Forwarding example. In the example illustrated by  FIGS. 3 and 4 , calling party A calls called party B. Called party B subscribes to Call Forwarding, as provided by B&#39;s wireless telecommunications Service Provider, so that calls made to B&#39;s Directory Number are forwarded to C.  
         [0028]     In the system  310  of this example, the Detector  12  includes an Originating Call Control Element (OCCE), and more specifically an Originating MSC (O-MSC)  312 . The O-MSC  312  is responsible for routing CR/MCD calls made to the subscriber B to one or more other destinations, such as for example to C.  
         [0029]     The system  310  also includes a Far End Switch  318  for establishing a CF call leg to C. The O-MSC  312  communicates with the Far End Switch  318  via the PSTN  330 . The system  310  also includes B&#39;s HLR  320  functioning as the RNE  20 . The system  310  also includes an SMS Message Center  340  for sending SMS messages to B as shall be described in further detail below.  
         [0030]     The Originating MSC  312  receives the incoming call destined for B by receiving an Initial Address Message (IAM) identifying B as the destination for the call from the Public Switched Telephone Network (PSTN) at  402 . In this example, the O-MSC  312  is B&#39;s Originating MSC which receives calls destined for B and is responsible for routing these incoming calls to B, including instances where B is roaming.  
         [0031]     The O-MSC  312  attempts to route the call to B by sending a Location Request Invoke (LOCREQ) message to B&#39;s HLR at  404 . The LOCREQ message identifies B, such as by B&#39;s DN or in some other manner, as the called party to which the call is to be routed to.  
         [0032]     B&#39;s HLR  320  determines that calls made to B are to be unconditionally call forwarded to C at  406 . As a result of this requirement, the HLR  320  retrieves a Call Forwarding Forward-to-Number (FTN) for C.  
         [0033]     The HLR responds to the LOCREQ of  404  with a Location Request Return Result response (locreq) at  408  providing C&#39;s FTN address, such as C&#39;s phone number, to the O-MSC for forwarding the call to C.  
         [0034]     The O-MSC  312  forwards the call to C at  410  by sending an IAM to the appropriate Far End Switch  318  responsible for setting up calls to C, as determined by locreq-response from  408 . The IAM includes C&#39;s address as the Called Party Number and B&#39;s address as the Original Called Number (OCN).  
         [0035]     As a result of C&#39;s number being recently disconnected, the Far End Switch  318  cannot route the call to C by establishing the call leg to C at  412 , resulting in a CR/MCD call leg creation failure. Thus, the Far End Switch  318 . informs the O-MSC  312  of this failure and the reason for this failure by sending a RELEASE (REL) message back to the O-MSC at  414  providing this information. The REL message can inherently indicate the CR/MCD call leg creation failure to the O-MSC  312 . The REL message can provide the MSC with the reason for the call failure, that being C&#39;s number has been disconnected. Further, if the number used for forwarding/redirecting calls to C is changed to a new number, instead of being disconnected, the Far End Switch  318  can include the new number in the REL message or some similar message.  
         [0036]     The O-MSC  312  receives the REL message  414  detecting the CR/MCD call leg creation failure and the reason for this failure as provided by the contents of the REL message at  416 . The O-MSC  312  then informs the. HLR  320  by sending a Call Forward (CF) Complaint message at  418  indicating to the HLR that there has been a CR/MCD call leg creation failure. The CF Complaint message also includes B&#39;s number as the called party number and C&#39;s number as the FTN, and the reason for the CR/MCD call leg creation failure. If C&#39;s number was changed, the CF Complaint message can include the new number.  
         [0037]     Because of the CF Complaint notification message of  418 , the HLR  320  deactivates Call Forwarding for B to C at  420 .  
         [0038]     Further, upon receiving the CF Complaint notification message of  418 , the HLR  320  notifies B that the CR/MCD destination number, C&#39;s number, being used as the FTN number, is not correct because it has been disconnected. As stated, this notification can be provided via a text message. The HLR  320  sends an SMS Message Delivery Point to Point (SMDPP) message to the SMS Message Center  340  at  422 . The SMDPP message includes B&#39;s number as well as the text message to be set to B notifying B that B&#39;s call forwarding to destination C is inoperative. The message can also indicate the reason for this, such as C&#39;s number has been disconnected, etc. The text message is sent to B at  424 . The message can also include C&#39;s new number if C&#39;s number was changed as opposed to being disconnected as described above.  
         [0039]     The Call Redirection (Call Forwarding) example can include calls forwarded more than once, that is calls forwarded from B to C and then from C to D. In this example, C has also forwarded to D using MSC-2. If the call leg creation to D fails because D is a bad destination, then the failure detector for the C-to-D leg will notify C&#39;s HLR, in a manner similar to the message at  418  above, but not B&#39;s HLR. The ISUP REL message will propagate backward from MSC-2 to MSC-1. Any MSC-1 that has implemented the invention will also have the intelligence to recognize that this CR/MCD call leg creation failure occurred during multi-hop forwarding due to parameters in the signaling such as Original Called Number and Redirecting Number not being equal for the multi-hop case. Further, the MSC-1 also knows that the CR/MCD call leg creation failure happened only on the last CR/MCD leg using MSC-2. The reason for not propagating the CF deactivations and failure notifications all the way backward to the O-MSC reduces any confusion that would occur on B&#39;s part since B may not know that the call is being forwarded from C to D.  
         [0040]     Referring now to  FIG. 5 , a call flow diagram is shown illustrating an example for a CDMA Flexible Alerting (FA) service in which a call leg creation failure occurs while establishing a CR/MCD call leg to a member of the FA group consisting of multiple call destinations. This failure can occur due to a bad destination being provided for that group member, such as may happen when the phone number for that member is disconnected, or in other known manners.  
         [0041]     A calls the Flexible Alerting Pilot B. In this example, B is a mobile connected to the CDMA wireless network. The call arrives at B&#39;s home, or O-MSC  312  in the form of an ISUP IAM for B at  502 . The O-MSC  312  sends a LOCREQ invoke message to the HLR for B at  504 .  
         [0042]     The HLR for B  320  determines that B is a pilot for a Flexible Alerting group, and retrieves information about the group members at  506 .  
         [0043]     The HLR  320  responds to the O-MSC by sending a locreq response at  508  that includes a Termination List including all of the call legs for this Flexible Alerting call. The Termination List in the locreq response includes 2 legs: one for a Local Termination for B, since B is registered within radio contact at the O-MSC  312  in this example, and the other one for a PSTN termination for C, another member of the Flexible Alerting group.  
         [0044]     From parameters in the locreq response  508 , the O-MSC  312  determines that this is a multi-leg call requiring it to set up call legs to both B and C. So the O-MSC  312  offers the call to B by sending a Page message to B at  510  to establish the call leg to B in a known manner.  
         [0045]     The O-MSC  312  also sends an IAM for C to the PSTN at  512  which includes C&#39;s number as the called party number to offer the call to C.  
         [0046]     At the Far End Switch responsible for connecting the call to C, the switch determines that C has been disconnected and that the call leg to C thus cannot be established at  512 .  
         [0047]     As a result, C&#39;s switch responds to the IAM of  512  with a REL message (a disconnect message) at  518 . The REL message includes the cause of the CR/MCD call leg creation failure, indicating that C has been disconnected.  
         [0048]     The O-MSC  312 , which is still waiting for the disposition for all the call legs of this multi-leg call, gets the disconnect message at  518 , and detects that this error needs to be reported to the HLR  320 . The FA call continues with processing of the other FA call legs made to other member(s) of the group in a manner which is known in the art. The O-MSC  312  sends a Redirection Complaint to the HLR  318  at  520 , including the fact that this is for the specific Flexible Alerting group owned by B, that the offending member DN is C, and that the cause for the complaint/failure is that C is disconnected.  
         [0049]     The HLR  320  deactivates member C from this Flexible Alerting group at  522 . The HLR  320  also notifies the owner of this FA group (B) that there is a bad member DN in the group at  522 . The HLR  320  sends an SMS message to B&#39;s short message service center at  524  and B is notified of the error via known SMS messaging at  528  in a similar manner as described above.  
         [0050]      FIG. 6  shows an example of the system  10  described above, which is shown generally at  610 , that includes an IMS communications network elements as part of a telecommunications network for performing Call Forwarding and/or Call Redirection in accordance with the invention. The system  610  includes an IMS Session Manager  612  functioning as the Detector  12  described above. An IMS based Application Server  620  functions as the RNE  20  described above. C&#39;s End Office (EO)  618  functions as the Far End Switch  18  described above. Also shown in  FIG. 6  are Media Gateway Control Function (MGCF) elements  650  for providing the circuit trunk, such as those using ISUP signaling as shown at  660 , to IP interfaces which are known in the art. A Home Subscriber Server (HSS) for B contains B&#39;s subscription information data including call forwarding indicators and addresses to the destinations the calls are to be forwarded to, such as C&#39;s address. Message Service function blocks are shown for SMS messaging at  690 , Voice Mail messaging at  692 , and E-mail messaging at  694 .  
         [0051]      FIG. 7  illustrates the call flow messaging sent between the network elements of  FIG. 6  for this Call Forwarding example. In the example illustrated by  FIGS. 6 and 7 , calling party A calls called party B. Called party B subscribes to Call Forwarding, as provided by B&#39;s telecommunications Service Provider, so that calls made to B&#39;s Directory Number are forwarded to C.  
         [0052]     A calls B at  702  and A&#39;s EO  662  sends an ISUP IAM toward B&#39;s home IMS at  704 . The MGCF  650  converts the IAM to a SIP INVITE message and sends it to the IMS Session Manager  612 . The IMS Session Manager  612  relays the INVITE message to B&#39;s AS  620  at  708 . The AS  620  queries the B&#39;s HSS- 640  at  710  to get B&#39;s feature data indicating what subscription features B subscribes to which can affect the call. Since B currently has Call Forwarding active to C as determined at  712 , the HSS  640  sends B&#39;s feature data to the AS  620  indicating such. The AS  620  notes that forwarding to C is active, adjusts the INVITE message accordingly by including C&#39;s address as well as A&#39;s address therein, and sends it back to the IMS Session Manager  612  at  716 . The IMS  612  sends the INVITE toward the appropriate MGCF  650  at  718 . The MGCF  650  converts the INVITE to an ISUP IAM and routes it toward C&#39;s EO  618  at  720 .  
         [0053]     The destination number for C has been recently been disconnected, and no additional info is available. C&#39;s EO  618  sends an ISUP RELease message backward, to the MGCF  650  which includes a Cause Code parameter indicating that C was disconnected, thereby providing the reason for the CR/MCD call leg creation failure. The ISUP REL message itself indicates that the CR/MCD call leg creation failure occurred.  
         [0054]     The MGCF  650  converts the ISUP REL into a SIP  604  message and sends to the IMS Session Manager at  726 . The IMS Session Manager  612  sends the  604  message to the AS  612  at  728 . The AS updates B&#39;s CF data in the HSS  640  at  730  to deactivate call forwarding thereby functioning as the RNE  20  as described above.  
         [0055]     The HSS  640  acknowledges the change at  732 . The AS  620  sends notification to B at  734  that the forward-to number is bad via Short message Service (SMS), and/or e-mail, and/or voice mail, again functioning as the RNE  20  as described above.  
         [0056]     The above description merely provides a disclosure of particular embodiments of the invention and is not intended for the purposes of limiting the same thereto. As such, the invention is not limited to only the above-described embodiments. Rather, it is recognized that one skilled in the art could conceive alternative embodiments that fall within the scope of the invention.