Abstract:
A call processing system for handling a call comprising a signaling interface configured to receive an initial address message wherein the initial address message identifies a calling party number, a processing system configured to process the calling party number to determine if the calling party number is in a first format accepted by a routing system and modify the initial address message if the calling party number is in a second format not accepted by the routing system, and the signaling interface further configured to transmit the modified initial address message to the routing system.

Description:
RELATED APPLICATIONS 
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     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     MICROFICHE APPENDIX 
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     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is related to the communications field, and in particular, to call processing systems and methods. 
     2. Description of the Prior Art 
     Mobile communications carriers typical handle calls connected from a mobile carrier network to destinations located on other networks such as the public switched telephone network (PSTN). To connect such a call destined for the PSTN, a mobile carrier routes the call from a mobile switch of their mobile network to a domestic switch of the PSTN. For example, the mobile carrier could route the call to a class 4 switch of the PSTN such as the DMS-250 offered by Nortel Networks, Inc. 
     During call setup, the mobile switch transmits call signaling to the domestic switch for call processing. The call signaling indicates the calling party number for the mobile phone which is used by the domestic switch to determine whether or not to connect the call and how to connect the call. For instance, the domestic switch might reject the call if the calling party number (CPN) indicates a customer that has delinquent bills. However, a problem arises when the CPN adheres to a format incompatible with a format recognized by the domestic switch therefore precluding the domestic switch from conducting call processing based on the CPN. For example, the DMS-250 class 4 switch recognizes CPNs that adhere to the North American Dialing Plan (NADP). If the CPN does not fit the NADP, the DMS-250 class 4 switch rejects the call. 
     Mobile carriers desire to provide international roaming services to customers, but these customers have calling party numbers that adhere to international formats and not the NADP. Thus, when the mobile carrier switch attempts to connect an international roaming call to the PSTN, the domestic switch of the PSTN does not recognize the international format of the calling party number and cannot conduct call processing based on the CPN. Lacking the ability to process the CPN, the domestic switch rejects the call. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention includes a call processing system for handling a call comprising a signaling interface configured to receive an initial address message wherein the initial address message identifies a calling party number, a processing system configured to process the calling party number to determine if the calling party number is in a first format accepted by a routing system and modify the initial address message if the calling party number is in a second format not accepted by the routing system, and the signaling interface further configured to transmit the modified initial address message to the routing system. 
     In some embodiments of the invention, the routing system comprises a switch of a public switched telephone network (PSTN). 
     In some embodiments of the invention, the signaling interface receives the initial address message from a mobile carrier switch. 
     In some embodiments of the invention, the processing system is configured to determine if a field of the initial address message is populated and populate the field if the field is not populated. 
     In some embodiments of the invention, the field comprises a charge number field and the charge number field is populated with a charge number. 
     In some embodiments of the invention, the field comprises an originating line identification field and the originating line identification field is populated with an originating line identification number. 
     In some embodiments of the invention, the routing system is configured to receive the modified initial address message and allow the call based on the charge number. 
     In some embodiments of the invention, the routing system is configured to receive the modified initial address message and allow the call based on the originating line identification number. 
     In some embodiments of the invention, the first format is compatible with the North American Dialing Plan. 
     In some embodiments of the invention, the call processing system comprises a service control point (SCP). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. 
         FIG. 1  illustrates a communication system in an embodiment of the invention. 
         FIG. 2  illustrates a flowchart for a call processing system in an embodiment of the invention. 
         FIG. 3  illustrates a communication system in an embodiment of the invention. 
         FIG. 4  illustrates the operation of a communication system in an embodiment of the invention. 
         FIG. 5  illustrates the operation of a communication system in an embodiment of the invention. 
         FIG. 6  illustrates a communication system in a embodiment of the invention. 
         FIG. 7  illustrates the operation of a communication system in an embodiment of the invention. 
         FIG. 8  illustrates a flowchart for a communication system in an embodiment of the invention. 
         FIG. 9  illustrates a call processing system in an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1-9  and the following description depict specific embodiments of the invention to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple embodiments of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
     First Embodiment Configuration and Operation 
     FIGS.  1 - 2   
       FIG. 1  illustrates communication system  100  in an embodiment of the invention. Communication system  100  includes call processing system  110  connected to call routing system  120 . Call processing system could comprise a service control point (SCP) or other similar call processing equipment. Call routing system  120  could comprise a switch of the Public Switched Telephone Network (PSTN). 
       FIG. 2  illustrates a flowchart describing the operation of communication system  100  in an embodiment of the invention. Call processing system  110  receives a message (Step  200 ) and determines if the message is an initial address message (IAM) (Step  210 ). If the message is not an IAM, call processing system  110  transmits the message for any remaining call processing (Step  240 ) to routing system  120 . If the message is an IAM, call processing system  110  determines if the calling party number stored in the calling party number field of the IAM is in an acceptable format (Step  220 ). If the format is acceptable, call processing system  110  transmits the message for any remaining call processing (Step  240 ) to routing system  120 . If the format is not acceptable, call processing system  110  modifies the IAM (Step  230 ). Next, call processing system  110  transmits the message for any remaining call processing (Step  240 ) to routing system  120 . 
     Second Embodiment Configuration and Operations 
     FIGS.  3 - 5   
       FIG. 3  illustrates communication system  300  in an embodiment of the invention. Communication system  300  includes call origination system  310 , call routing system  320 , call processing system  330 , and destination system  340 . Call processing system  330  is coupled to call origination system  310  and call routing system  320 . Call routing system  320  is connected to call origination system  310  and destination system  340 . Call origination system  310  could comprise a switch of the public switched telephone network (PSTN) or a mobile telephone switch operated by a wireless telecommunications carrier. Call routing system  320  comprises a collection of switches in the PSTN. Call processing system  330  comprises a service control point (SCP). Destination system  340  could comprise a switch, a mobile switch, a destination device such as a telephone, or a combination of such elements. 
       FIG. 4  illustrates the operation of communication system  300  in an embodiment of the invention. Call origination system  310  transmits an initial address message (IAM) for a call to call routing system  320 . Call routing system  320  receives the IAM and sends the IAM to call processing system  330 . Call processing system  330  receives the IAM and processes the calling number field in the IAM to determine if the calling party number fits an acceptable format. If the calling party does not fit an acceptable format, call processing system  330  modifies the IAM. The IAM is modified based upon requirements of call routing system  320  to allow call connection through routing system  320  to destination system  340 . Call processing system  330  sends the modified IAM to call routing system  320 . The call is then connected from call origination system  310  to destination system  340 . 
       FIG. 5  illustrates the operation of communication system  300  in an embodiment of the invention. Call origination system  310  transmits an initial address message (IAM) for a call to call processing system  330 . Call processing system  330  receives the IAM and processes the calling number field in the IAM to determine if the calling party number fits an acceptable format. If the calling party does not fit an acceptable format, call processing system  330  modifies the IAM. The IAM is modified based upon requirements of call routing system  320  to allow call connection through routing system  320  to destination system  340 . Call processing system  330  sends the modified IAM to call routing system  320 . The call is then connected from call origination system  310  to destination system  340 . 
     Third Embodiment Configuration and Operations 
     FIGS.  6 - 8   
       FIG. 6  illustrates communication system  600  in an embodiment of the invention. Communication system  600  includes cell phone  610 , mobile carrier switch  621 , signal transfer point (STP)  625 , international roaming service provider system (IRSP)  630 , class 4 switch  622 , local switch  624 , and called party  640 . Cell phone  610  connects to mobile carrier switch  621  by a wireless connection. Class 4 switch  622  is connected to mobile carrier switch  621  and local switch  624 . STP  625  is connected to mobile carrier switch  621 , class 4 switch  622 , and IRSP  630 . STP  625  could also be connected to local switch  624  although that is not shown for clarity. IRSP  630  comprises an SCP. Called party  640  is connected to local switch  624 . Local switch  624  could comprise a central office switch, a central branch exchange (CBX), or any other similar type of switching equipment that connects called party  640  to the PSTN. 
       FIG. 7  illustrates the operation of communication system  600  in an embodiment of the invention. In this embodiment, cell phone  610  is a foreign device roaming on a domestic network. Cell phone  610  sends a called number to mobile carrier switch  621 . Mobile carrier switch  621  typically sends an integrated services digital network user part (ISUP) message to STP  625 . STP  625  receives the ISUP message and passes the ISUP message to IRSP  630 . STP  625  passes the ISUP message to IRSP  630  based upon a determination that the OPC included in the ISUP message indicates that the ISUP message originated from mobile carrier switch  621 . Alternatively, STP  625  could pass the ISUP message to IRSP  630  based upon a determination that destination point code (DPC) included in the ISUP message indicates IRSP  630  as the destination for the ISUP message. 
     IRSP receives the ISUP message and passes any ISUP message that is not an IAM to class 4 switch  622  without any further processing. If the ISUP message is an IAM, IRSP  630  inspects the calling number in the IAM to determine if the calling number fits an acceptable format. If the calling number fits the appropriate format, IRSP  630  sends the unmodified IAM to class 4 switch  622 . If the calling number does not fit the appropriate format, IRSP  630  modifies the IAM. The IAM is modified based upon requirements of DSM  250  switch  622 . If the calling number fits an international format, IRSP  630  modifies the IAM so that class 4 switch  622  will connect the call. Class 4 switch  622  receives the modified IAM, proceeds with call setup messaging, and connects the call from cell phone  610  to called party  640 . 
       FIG. 8  illustrates a flowchart that describes the operation of communication system  600  in an embodiment of the invention. Mobile carrier  621  passes an ISUP message to STP  625 . STP  625  passes the ISUP message to ISRP for SS7 ISUP stack processing (Step  800 ). IRSP determines if the message is an IAM (Step  810 ). If the ISUP message is not an IAM, IRSP updates the DPC and OPC (Step  880 ), completes any remaining SS7 ISUP stack processing (Step  890 ), and transmits the ISUP message to class 4 switch  625  (Step  899 ). 
     If the ISUP message is an IAM, IRSP  630  determines if the calling party number (CPN) in the calling party field of the IAM is in an international format (Step  820 ). If the CPN is not in an international format, IRSP updates the destination point code (DPC) and origination point code (OPC) (Step  880 ), completes any remaining SS7 ISUP stack processing (Step  890 ), and transmits the ISUP message to class 4 switch  625  (Step  899 ). If the CPN is in an international format, IRSP next determines if the charge number field of the IAM is populated (Step  830 ). 
     If the charge number field is populated, IRSP updates the DPC and OPC (Step  880 ), completes any remaining SS7 ISUP stack processing (Step  890 ), and transmits the ISUP message to class 4 switch  625  (Step  899 ). If the charge number field is not populated, IRSP  630  creates a copy of the IAM message (Step  840 ) and populates the charge number field with a pseudo charge number (Step  850 ). 
     Next, IRSP  630  determines if the originating line information (OLI) field is populated (Step  860 ). If the OLI field is populated, IRSP updates the DPC and OPC (Step  880 ), completes any remaining SS7 ISUP stack processing (Step  890 ), and transmits the ISUP message to class 4 switch  625  (Step  899 ). If the OLI field is not populated, IRSP  630  populates the OLI field with a pseudo OLI (Step  870 ), updates the DPC and OPC (Step  880 ), completes any remaining SS7 ISUP stack processing (Step  890 ), and transmits the ISUP message to class 4 switch  625  (Step  899 ). 
     Class 4 switch  625  receives the ISUP message and connects the call. Advantageously, adding information to the charge number field and the OLI field to a 15 digit CPN allows class 4 switch  625  to complete the call to an end location with the calling party number intact. Class 4 switch  625  will connect the call even though the calling party number fits an international format because a populated charge number field indicates the call can be charged to a customer. Similarly, a populated OLI field indicates to class 4 switch  625  a line from which calls should be connected. The call could terminate within the PSTN or to an international location. If the call terminates to an international location, the class 4 switch  625  would connect the call to a DMS  300  switch for transport to an international telecommunication network. A DMS  300  switch could also support the operation described by  FIG. 7 . 
     Call Processing System— FIG. 9   
       FIG. 9  illustrates call processing system  900  in an embodiment of the invention. Call processing system  900  includes signaling interface  920 , processing system  930 , storage system  940 , and software  950 . Storage system  940  stores software  950 . Processing system  930  is linked to signaling interface  920 . Call processing system  900  could be comprised of a programmed general-purpose computer, although those skilled in the art will appreciate that programmable or special purpose circuitry and equipment may be used. Call processing system  900  may use a client server architecture where operations are distributed among a server system and client devices that together comprise elements  920 - 950 . 
     Signaling interface  920  could comprise a network interface card, modem, port, or some other communication device. Signaling interface  920  may be distributed among multiple communication devices. Processing system  930  could comprise a computer microprocessor, logic circuit, or some other processing device. Processing system  930  may be distributed among multiple processing devices. Storage system  940  could comprise a disk, tape, integrated circuit, server, or some other memory device. Storage system  940  may be distributed among multiple memory devices. 
     Processing system  930  retrieves and executes software  950  from storage system  940 . Software  950  may comprise an operating system, utilities, drivers, networking software, and other software typically loaded onto a general-purpose computer. Software  950  could also comprise an application program, firmware, or some other form of machine-readable processing instructions. When executed by the processing system  930 , software  950  directs processing system  930  to operate as described for call processing system  110 ,  330 , and IRSP  630 .