PATENT ABSTRACT
The present invention provides systems and methods for providing additional or modified subscriber profile information of an outbound roamer of a Home Public Mobile Network (HPMN), wherein the outbound roamer is roaming in a Visited Public Mobile Network (VPMN) in an LTE environment. The system includes a monitoring block to monitor Diameter and MAP transaction messages on S6, SI and Cx interfaces. The system includes subscriber and roamer databases storing subscriber or roamer records, wherein each record comprises at least the International Mobile Subscriber Identity (IMSI) of the subscriber or roamer. The system includes a detection block to detect whether provisioning of an alternate roaming profile is required for the subscriber or roamer, and further includes a provisioning block to provision the generated alternate roaming profile of the subscriber or roamer to LTE nodes holding a subscriber or roamer profile (i.e., MME, the IM-SSF or the SCSCF).

PATENT DESCRIPTION
RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Patent Application No. 61/756,950 entitled “LTE EVOLUTION IN DCG/PMMS” filed on Jan. 25, 2013, the entirety of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    The present invention generally relates to roamers. More specifically, the present invention relates to Profile and mobility management system (PMMS) for LTE environment. 
         [0003]    With the introduction of LTE, multiple changes affect the dynamic profile management of the customers. Firstly the user profile is maintained in various nodes, depending on the required profile modification. Typically, the user profile might require adaptation in the EPC domain (MME), the IMS domain (S-CSCF) and the CAMEL interworking domain (IM-SSF). 
         [0004]    The involvement of the different nodes depends on the purpose of the change. For example, a call barring in VoLTE may require the introduction of a TAS for handling Communication Barring (or any other supplementary services) and hence, the adjustment of the Initial Filter Criteria given in the user-data/service profile shared between the S-CSCF and the HSS upon registration. 
         [0005]    The call barring is supported in IMS under the term Communication Barring—(ref. 3GPP 24.611). It should be noted that Barring of International Calls is a 3GPP Release 9 feature. 
         [0006]    A MSISDN change at MME to cope with specific multi-device services or APN parameters. The use of IM-SSF function may require sending IM-CSI with adjusted parameters for specific use case (e.g. a roaming service de-coupling as planned in Europe). 
         [0007]    In view of the above there is a requirement for a system and method for enhanced profile and mobility management system (PMMS) for LTE environment. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed to a system, method and computer program product for The present invention provides a system and method for providing additional or modified subscriber profile information of an outbound roamer of a Home Public Mobile Network (HPMN), wherein the outbound roamer is roaming in a Visited Public Mobile Network (VPMN) in an LTE environment. The system includes a monitoring block to monitor Diameter and MAP transaction messages on the S6, SI and Cx interface. The system further includes subscriber and roamer databases storing subscriber or roamer records, wherein the record comprises at least the International Mobile Subscriber Identity (IMSI) of the subscriber or the roamer. The system further includes detection block to detect whether provisioning of an alternate roaming profile is required for the subscriber or roamer. The system further includes a provisioning block to provision the generated alternate roaming profile of the subscriber or the roamer to LTE nodes holding a subscriber or roamer profile (i.e. MME, the IM-SSF or the SCSCF). 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]    In the drawings, the same or similar reference numbers identify similar elements or acts. 
           [0010]      FIG. 1  illustrates a block diagram of a system for overview of possible profile modification requirements in LTE environment, in accordance with an embodiment of the present invention. 
           [0011]      FIG. 2  illustrates a block diagram of method for Fallback to provision the HSS/HLR leading to a dynamic Profile modification at the MME, via HSS-originated signaling, dynamic CAMEL gateway, in accordance with an embodiment of the present invention. 
           [0012]      FIG. 3  illustrates architecture for modifying profile of an outbound roamer, in accordance with an embodiment of the present invention. 
           [0013]      FIG. 4  illustrates architecture for modifying profile of an outbound roamer, in accordance with another embodiment of the present invention. 
           [0014]      FIG. 5  illustrates architecture for modifying profile of a roamer in LTE environment, in accordance with another embodiment of the present invention. 
           [0015]      FIG. 6  shows an overview of enhanced PMMS in accordance with an embodiment of the invention. 
           [0016]      FIG. 7  illustrates a flowchart for monitoring-based PMMS implementation, in accordance with an embodiment of the present invention. 
           [0017]      FIG. 8  illustrates a flow diagram of Implementation of PMMS in Proxy mode in accordance with an embodiment of the present invention. 
           [0018]      FIG. 9  illustrates a flow diagram monitoring-based PMMS implementation for an outbound roamer in accordance with an embodiment of the present invention. 
           [0019]      FIG. 10  illustrates a flow diagram of Profile Modification of an outbound roamer using a monitoring approach in accordance with an embodiment of the present invention. 
           [0020]      FIG. 11  illustrates a flow diagram of sending the Profile Management MAP IDR Message, with a fallback strategy in accordance with an embodiment of the present invention. 
           [0021]      FIG. 12  illustrates a flow diagram for Profile Modification of an LTE outbound roamer using a proxy approach in accordance with an embodiment of the present invention. 
           [0022]      FIG. 13  illustrates a flow diagram for monitoring-based PMMS implementation for an inbound roamer in accordance with an embodiment of the present invention. 
           [0023]      FIG. 14  illustrates a flow diagram of Profile Modification of an inbound roamer using a monitoring approach in accordance with an embodiment of the present invention. 
           [0024]      FIG. 15  illustrates a flow diagram of sending the Profile Management Diameter IDR Message in accordance with an embodiment of the present invention. 
           [0025]      FIG. 16  illustrates a flow diagram of sending Profile Modification of a LTE inbound roamer using a proxy approach in accordance with an embodiment of the present invention. 
           [0026]      FIG. 17  illustrates a flow diagram of monitoring-based PMMS implementation for an IMS subscriber requiring a IM-CSI modification in accordance with an embodiment of the present invention. 
           [0027]      FIG. 18  illustrates a flow diagram of Profile Modification of an IMS subscriber requiring a IM-CSI modification using a monitoring approach in accordance with an embodiment of the present invention. 
           [0028]      FIG. 19  illustrates a flow diagram of sending the Profile Management MAP NSDM Message in accordance with an embodiment of the present invention. 
           [0029]      FIG. 20  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
           [0030]      FIG. 21  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a monitoring approach in accordance with an embodiment of the present invention. 
           [0031]      FIG. 22  illustrates a flow diagram for Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
           [0032]      FIG. 23  illustrates a flow diagram for sending the Profile Management Diameter PPR Message in accordance with an embodiment of the present invention. 
           [0033]      FIG. 24  illustrates a flow diagram for Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
           [0034]      FIG. 25  illustrates a flow diagram for Profile Modification of a roamer using a monitoring approach in accordance with an embodiment of the present invention. 
           [0035]      FIG. 26  illustrates a flow diagram for Profile Modification of a LTE roamer using a proxy approach in accordance with an embodiment of the present invention. 
           [0036]      FIG. 27  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a monitoring approach in accordance with an embodiment of the present invention. 
           [0037]      FIG. 28  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    In the foregoing description, the HPMN is a network to which an inbound roamer is originally subscribed while the VPMN is a network where the inbound roamer is situated while he is roaming. 
         [0039]      FIG. 1  illustrates a block diagram of a system for overview of possible profile modification requirements in LTE environment, in accordance with an embodiment of the present invention. The solution is based on functional blocks i.e. an optional monitoring block, a detection block, a provisioning and generation block and an optional HSS provisioning block. The use of the optional depends on the implementation mode chosen by the operator. The enhanced PMMS solution can be implemented using a monitoring approach—where the protocols are observed without any interference from the system—or a proxy approach where the messages are routed through the system. 
         [0040]      FIG. 2  illustrates a block diagram of method for Fallback to provision the HSS/HLR leading to a dynamic Profile modification at the MME, via HSS-originated signaling, dynamic CAMEL gateway, in accordance with an embodiment of the present invention. 
         [0041]      FIG. 3  illustrates architecture for modifying profile of an outbound roamer in accordance with an embodiment of the present invention. The system comprises VPMN  102  communicating with HPMN  104  via a SS7 interface  106 . VPMN  102  comprises a monitoring block  108  coupled to a dynamic CAMEL gateway  110 , a VPMN GMSC/STP  112 , and a VPMN VLR/VMSC  114 . Dynamic CAMEL gateway  110  and VPMN VLR/VMSC  114  are coupled to VPMN GMSC/STP  112 . HPMN  104  comprises a HPMN STP  116  and a HPMN HLR  118 . VPMN GMSC/STP  112  communicates with HPMN STP  116  via SS7 interface  106 . HPMN HLR  118  is coupled to HPMN STP  116 . In accordance with an embodiment of the present invention, gsmSSF may be integrated with VPMN VLR/VMSC  114 . Although the system is described using essential components, however, it will be obvious to a person skilled in the art that the system includes various other components not shown in the figure, for the purpose of clarity. 
         [0042]    In an embodiment of the present invention, the interface between monitoring block  108  and dynamic CAMEL gateway  110  may be a TCP/IP based interface. Monitoring block  108  and dynamic CAMEL gateway  110  may belong to different vendors. However, monitoring block  108  and dynamic CAMEL gateway  110  may belong to a same vendor. 
         [0043]    In accordance with an embodiment of the present invention, monitoring block  108  and dynamic CAMEL gateway  110  may be physically integrated in the same box. In accordance with another embodiment of the present invention, monitoring block  108  and dynamic CAMEL gateway  110  may be installed separately. 
         [0044]    VPMN VLR/VMSC  114  sends a MAP transaction message  120  to HPMN HLR  118  when an inbound roamer registers at VPMN VLR/VMSC  114 . MAP transaction message  120  includes a MAP Location Update transaction. Monitoring block  108  taps international roaming links employed by SS7 interface  106  and used for sending MAP transaction message  120 . Monitoring block  108  monitors MAP transaction message  120  and informs dynamic CAMEL gateway  110  when it detects a successful MAP Location Update. In accordance with an embodiment of the present invention, the monitoring may be in the path of signaling. In accordance with another embodiment of the present invention, monitoring may be non-intrusive. Further, monitoring block  108  provides details of the inbound roamer to dynamic CAMEL gateway  110 . The details provided by monitoring block  108  include at least one of an International Mobile Subscriber Identity (IMSI), the HPMN HLR, the VPMN VLR/VMSC, a Mobile Station International ISDN Number (MSISDN), a supported CAMEL phase by the HPMN, all CSIs (for example, O-CSI, SS-CSI, VT-CSI and the like) and combination thereof. 
         [0045]    If the details do not contain a MO-CSI, dynamic CAMEL gateway  110  generates the MO-CSI of the inbound roamer. In accordance with an embodiment of the present invention, the MO-CSI comprises a service key and an address of a Global System for Mobile communication Service Control Function (gsmSCF). The gsmSCF address may be the address of dynamic CAMEL gateway  110  or an existing gsmSCF of VPMN  102 . Dynamic CAMEL gateway  110  provides the generated MO-CSI to VPMN VLR/VMSC  114  via VPMN GMSC/STP  112 . Dynamic CAMEL gateway  110  maintains records relating to at least one HPMN, CAMEL phases supported by the HPMN, and at least one inbound roamer details. 
         [0046]      FIG. 4  illustrates architecture for modifying profile of an outbound roamer, in accordance with another embodiment of the present invention. 
         [0047]      FIG. 5  illustrates architecture for modifying profile of a roamer in LTE environment, in accordance with another embodiment of the present invention. 
         [0048]      FIG. 6  shows an overview of enhanced PMMS in accordance with an embodiment of the invention. The following call flows show how the system is implemented for modifying the profile of a subscriber roaming in LTE or using the IMS service. 
         [0049]      FIG. 7  illustrates a flowchart for monitoring-based PMMS implementation, in accordance with an embodiment of the present invention. 
         [0050]      FIG. 8  illustrates a flow diagram of Implementation of PMMS in Proxy mode in accordance with an embodiment of the present invention. 
         [0051]      FIG. 9  illustrates a flow diagram monitoring-based PMMS implementation for an outbound roamer in accordance with an embodiment of the present invention. 
         [0052]      FIG. 10  illustrates a flow diagram of Profile Modification of an outbound roamer using a monitoring approach in accordance with an embodiment of the present invention. 
         [0053]      FIG. 11  illustrates a flow diagram of sending the Profile Management MAP IDR Message, with a fallback strategy in accordance with an embodiment of the present invention. 
         [0054]      FIG. 12  illustrates a flow diagram for Profile Modification of an LTE outbound roamer using a proxy approach in accordance with an embodiment of the present invention. 
         [0055]      FIG. 13  illustrates a flow diagram for monitoring-based PMMS implementation for an inbound roamer in accordance with an embodiment of the present invention. 
         [0056]      FIG. 14  illustrates a flow diagram of Profile Modification of an inbound roamer using a monitoring approach in accordance with an embodiment of the present invention. 
         [0057]      FIG. 15  illustrates a flow diagram of sending the Profile Management Diameter IDR Message in accordance with an embodiment of the present invention. 
         [0058]      FIG. 16  illustrates a flow diagram of sending Profile Modification of a LTE inbound roamer using a proxy approach in accordance with an embodiment of the present invention. 
         [0059]      FIG. 17  illustrates a flow diagram of monitoring-based PMMS implementation for an IMS subscriber requiring a IM-CSI modification in accordance with an embodiment of the present invention. 
         [0060]      FIG. 18  illustrates a flow diagram of Profile Modification of an IMS subscriber requiring a IM-CSI modification using a monitoring approach in accordance with an embodiment of the present invention. 
         [0061]      FIG. 19  illustrates a flow diagram of sending the Profile Management MAP NSDM Message in accordance with an embodiment of the present invention. 
         [0062]      FIG. 20  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
         [0063]      FIG. 21  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a monitoring approach in accordance with an embodiment of the present invention. 
         [0064]      FIG. 22  illustrates a flow diagram for Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
         [0065]      FIG. 23  illustrates a flow diagram for sending the Profile Management Diameter PPR Message in accordance with an embodiment of the present invention. 
         [0066]      FIG. 24  illustrates a flow diagram for Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. 
         [0067]      FIG. 25  illustrates a flow diagram for Profile Modification of a roamer using a monitoring approach in accordance with an embodiment of the present invention. The PMMS monitors using in-signaling techniques the diameter message to modify the message. 
         [0068]      FIG. 26  illustrates a flow diagram for Profile Modification of a LTE roamer using a proxy approach in accordance with an embodiment of the present invention. The PMMS monitors using in-path techniques the diameter message to modify the message. 
         [0069]      FIG. 27  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a monitoring approach in accordance with an embodiment of the present invention. In this case, the PMMS module uses in-signaling technique to tap the MAP ATSI message to modify it. 
         [0070]      FIG. 28  illustrates a flow diagram for IM-CSI Profile Modification of a IMS subscriber using a proxy approach in accordance with an embodiment of the present invention. In this case, the PMMS module uses in path technique to receive MAP ATSI message assuming HLR is not provisioned with any IM-CSI. 
         [0071]    It should be noted that the various components disclosed herein may be described using computer aided design tools and/or expressed (or represented), as data and/or instructions embodied in various computer-readable media, in terms of their behavioral, register transfer, logic component, transistor, layout geometries, and/or other characteristics. Computer-readable media in which such formatted data and/or instructions may be embodied include, but are not limited to, non-volatile storage media in various forms (e.g., optical, magnetic or semiconductor storage media) and carrier waves that may be used to transfer such formatted data and/or instructions through wireless, optical, or wired signaling media or any combination thereof. 
         [0072]    Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in a sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number respectively. Additionally, the words “herein,” “hereunder,” “above,” “below,” and words of similar import refer to this application as a whole and not to any particular portions of this application. When the word “or” is used in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list and any combination of the items in the list. 
         [0073]    The above description of illustrated embodiments of the CCSIR is not intended to be exhaustive or to limit the CCSIR to the precise form disclosed. While specific embodiments of, and examples for, the CCSIR are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the CCSIR, as those skilled in the art will recognize. The teachings of the CCSIR provided herein may be applied to other processing systems and methods. They may not be limited to the systems and methods described above. 
         [0074]    The elements and acts of the various embodiments described above may be combined to provide further embodiments. These and other changes may be made to the CCSIR in light of the above detailed description. 
       Other Variations 
       [0075]    Provided above for the edification of those of ordinary skill in the art, and not as a limitation on the scope of the invention, are detailed illustrations of a scheme for generating and provisioning the CSI of an inbound roamer in a wireless communication network, who has moved onto a VPMN and is detected as being registering with the VPMN. Numerous variations and modifications within the spirit of the present invention will of course occur to those of ordinary skill in the art in view of the embodiments that have now been disclosed. For example, while in the described embodiments, the present invention is implemented primarily from the point of view of GSM mobile networks, the present invention may also be effectively implemented on CDMA, 3G, WCDMA, GPRS, etc., or any other network of common carrier telecommunications in which end users are normally configured to operate within a “home” network to which they normally subscribe, but have the capability of also operating on other neighboring networks. 
         [0076]    The examples under the present invention, detailed in the illustrative examples contained here, are described using terms and constructs drawn largely from GSM mobile telephony infrastructure. However, use of these examples should not be interpreted to limiting the invention to those media. The capabilities of the visited or non-accustomed network may be of use and provided through any type of telecommunications medium, including without limitation: (i) any mobile telephony network including, without limitation, GSM, 3GSM, 3G, CDMA, WCDMA or GPRS, satellite phones or other mobile telephone networks or systems; (ii) any so-called WiFi apparatus normally used in a home or subscribed network, but also configured for use on a visited or non-home or non-accustomed network, including apparatus not dedicated to telecommunications such as personal computers, Palm-type or Windows Mobile devices; (iii) an entertainment console platform such as Sony Playstation, PSP or other apparatus that are capable of sending and receiving telecommunications over home or non-home networks, or even (iv) fixed-line devices made for receiving communications, but capable of deployment in numerous locations while preserving a persistent subscriber id such as the eye2eye devices from Dlink, or telecommunications equipment meant for voice over IP communications such as those provided by Vonage or Packet8. 
         [0077]    In describing certain embodiments of dynamic CSI generation under the present invention, this specification follows the path of a telecommunications call from a calling party to a called party. For the avoidance of doubt, that call may be for a normal voice call, in which the subscriber telecommunications equipment is also capable of visual, audiovisual or motion-picture display. Alternatively, those devices or calls may be for text, video, pictures or other communicated data. 
       TECHNICAL REFERENCES, THE ENTIRETY OF EACH OF WHICH IS INCORPORATED BY REFERENCE HEREIN 
       [0000]    
       
         GSM 902 on MAP specification 
         GSM 340 on SMS 
         GSM 378 on CAMEL 
         GSM 978 on CAMEL Application Protocol 
         GSM 379 on CAMEL Support of Optimal Routing (SOR) 
         GSM 318 on CAMEL Basic Call Handling 
         ITU-T Recommendation Q.1214 (1995), Distributed functional plane for intelligent network CS-1. 
         ITU-T Recommendation Q.1218 (1995), Interface Recommendation for intelligent network CS-1. 
         ITU-T Recommendation Q.762 (1999), Signaling system No. 7—ISDN user part general functions of messages and signals. 
         ITU-T Recommendation Q.763 (1999), Signaling system No. 7—ISDN user part formats and codes. 
         ITU-T Recommendation Q.764 (1999), Signaling system No. 7—ISDN user part signaling procedures. 
         ITU-T Recommendation Q.766 (1993), Performance objectives in the integrated services digital network application. 
         ITU-T Recommendation Q.765 (1998), Signaling system No. 7—Application transport mechanism. 
         ITU-T Recommendation Q.769.1 (1999), Signaling system No. 7—ISDN user part enhancements for the support of Number Portability. 
       
     
         [0000]    
       
         
               
               
             
           
               
                 APPENDIX 
               
               
                   
               
               
                 Acronym 
                 Description 
               
               
                   
               
             
             
               
                 BCD 
                 Binary Coded Decimal 
               
               
                 CAP 
                 CAMEL Application Part 
               
               
                 CAMEL 
                 Customized Applications for Mobile network Enhanced Logic 
               
               
                 CB 
                 Call Barring 
               
               
                 CC 
                 Country Code 
               
               
                 CLI 
                 Calling Line Identification 
               
               
                 CON 
                 IN/CAMEL Connect 
               
               
                 CSI 
                 CAMEL Subscription Information 
               
               
                 CUE 
                 IN/CAMEL Continue 
               
               
                 DPC 
                 Destination Point Code 
               
               
                 ERB 
                 Event Report Basic call state machine 
               
               
                 FCI 
                 Furnish Charging Information 
               
               
                 GGSN 
                 Gateway GPRS Support Node 
               
               
                 GMSC-H 
                 HPMN Gateway MSC 
               
               
                 GPRS 
                 General Packet Radio Service 
               
               
                 GPRS-CSI 
                 GPRS CSI 
               
               
                 gsmSCF 
                 GSM service control function 
               
               
                 gsmSSF 
                 GSM service switch function 
               
               
                 HLR 
                 Home Location Register 
               
               
                 HLR-H 
                 HLR from HPMN 
               
               
                 HPMN 
                 Home Public Mobile Network 
               
               
                 IDP 
                 Initial Detection Point IN/CAP message 
               
               
                 IMSI 
                 International Mobile Subscriber Identifier 
               
               
                 IN 
                 Intelligent Network 
               
               
                 ISD 
                 Insert Subscriber Data 
               
               
                 ISUP 
                 ISDN User Part 
               
               
                 LUP 
                 MAP Location Update 
               
               
                 MAP 
                 Mobile Application Part 
               
               
                 ME 
                 Mobile Equipment 
               
               
                 MNC 
                 Mobile Network Code 
               
               
                 MSC 
                 Mobile Switch Center 
               
               
                 MSISDN 
                 Mobile Subscriber ISDN 
               
               
                 MSRN 
                 Mobile Station Roaming Number 
               
               
                 NDC 
                 National Destination Code 
               
               
                 O-CSI 
                 Originating CSI 
               
               
                 ODB 
                 Operator Determined Barring 
               
               
                 PLN 
                 Prepaid Local Number 
               
               
                 RRB 
                 Request Report Basic call state machine 
               
               
                 SCCP 
                 Signal Connection Control Part 
               
               
                 SCP 
                 Service Control Point 
               
               
                 SGSN 
                 Service GPRS Support Node 
               
               
                 SPC 
                 Signal Point Code 
               
               
                 SRI 
                 Send Routing Information 
               
               
                 SRI-SM 
                 Send Routing Information for Short Message 
               
               
                 SS7 
                 Signaling System 7 
               
               
                 SS-CSI 
                 Supplementary Service CSI 
               
               
                 STP 
                 Signal Transfer Point 
               
               
                 STP-H 
                 HPMN STP 
               
               
                 T-CSI 
                 Terminating CSI 
               
               
                 USSD 
                 Unstructured Supplementary Service Data 
               
               
                 VLR 
                 Visited Location Register 
               
               
                 VLR-V 
                 VLR from VPMN 
               
               
                 VMSC 
                 Visited Mobile Switch Center 
               
               
                 VMSC-V 
                 VMSC from VPMN 
               
               
                 VPMN 
                 Visited Public Mobile Network 
               
               
                 VT-CSI 
                 Visiting network Terminating CSI