IMSI Migration Team Status Update

1. IMSI Migration TeamStatus Update Alain Bouvier alain.bouvier@ericsson.com CDG International Roaming Team Meeting Las Vegas, NV, November 30th-December 1st, 2005

2. Problem Statement • The problem is MIN/IRM exhaustion; • The solution is the introduction of True IMSI subscriber identities; • The main challenge associated with the introduction of True IMSI subscriber identities is to (a)maintain inter-carrier roaming services through a transition away from MIN/IRM and, at the same time, (b) allow each carrier to have their own IMSI Migration timeline. Considering the need to migrate to True IMSI and the impact this could have on international roaming, the CDG IRT has started investigating the matter by looking into potential IMSI Migration plans.

3. Team • Core Team Members:Alain Bouvier (Ericsson) - alain.bouvier@ericsson.com;Douglas Rollender (Lucent Technologies) - rollender@lucent.com;Andrew Hunter (Qualcomm) - ahunter@QUALCOMM.COM; • Distribution List:IMSI-MIGRATION@OBERON.3DIINC.COM Want to join the core team or simply add your name to the distribution list? Send a request to Sara Aab at: saab@qualcomm.com

4. Scope • Educate and raise awareness with regard to the MIN/IRM exhaustion issue and to the need to migrate to true IMSI; • Establish and validate the requirements for an IMSI Migration Plan; • Propose IMSI Migration options and recommend anIMSI Migration Plan; • Edit and publish the“IMSI Migration Guidelines” CDG reference document;

5. Deliverables • CDG Reference Document #126“MIN-based IMSI to True IMSI Migration Guidelines” A draft version of this document can be found on the CDG web site at the following location: “Members Only” - “Team Info” - “International Roaming” - “Documents In Development”

6. General Requirements The IMSI Migration Plan: • Shall avert MIN/IRM exhaustion; • Shallsupport thetransitioning to IMSI-based routing of inter-carrier signaling independently of the subscriber identifier used in ANSI/IS-41 messages or within the home network i.e. MINs/IRMs can be used as subscriber identifiers while Full IMSI is used for routing inter-carrier signaling; • Shallnot impact the SS7/C7 signaling networks except for normal STP E.212 GTT tables updates; • Shallnot impact current solution for E.214 mapping to NANP E.164 CC-NC; • Shallnot impact the IS-2000 over-the-air MSID transmission bandwidth saving mechanism; • Shallnot impact enhanced PRL (ePRL); • Shall address all current uses of MINs/IRMs; • Shall allow flexibility for operators to manage implementation timeline and roaming agreements; • Shall maintain backward compatibility with MIN/IRM Only Systems as per the recommended timeline; • Shall allow operators to reuse MINs/IRMs as the 10 least significant True IMSI digits; • Shallnot impact operators mobile subscribers identity administration (MSN, IRM5/6 and MSIN).

7. IMSI Migration Plan Key Requirements • Decoupling Local Subscriber Id from Network Id: • Local Subscriber Id for home subscriber identification; • Network Id for inter-network routing. • Detecting non-qualifying “MIN-based IMSI”; • Detecting qualifying “MIN-based IMSI” with a MIN/IRM Home Subscription Type (HST); • Supporting 2-digit MNC. MBI MSN MIN ICB IRM5/6 IRM ESC Code MIN/IRM Non-qualifying “MIN-based IMSI” HNI MIN/IRM Qualifying “MIN-based IMSI” HNI MSIN “True IMSI” Network Id Local Subscriber Id Global Subscriber Id

8. IMSI Migration Plan & Subscriber Identity .1. MIN/IRM or IMSI? VLR MIN / IMSI HLR MIN / IMSI (A) (B) (C) Roaming MS (D) Visited Network Home Network A)VLR Addressing. B)Inter-network signaling (TCAP ANSI/IS-41) and VLR addressing. C)Inter-network signaling (TCAP ANSI/IS-41) and HLR addressing. D)Inter-network routing (SCCP GT Routing and PC Routing).

9. IMSI Migration Plan & Subscriber Identity .2. All the proposed IMSI Migration Plans need to address some of the following migration issues: • VLR Addressing with MIN/IRM or with Full IMSI? • Inter-network signaling (TCAP) with MSID = MIN/IRM or IMSI? • Inter-network routing (SCCP GTR/PCR) based on MIN/IRM or on Full IMSI? In order to answer these questions, the serving system may have to determine if a received IMSI is a non-qualifying “MIN-based IMSI” and if it is associated with a MIN/IRM Home Subscription Type (HST). • The proposed solutions are: • The Core Network Centric (MSC) solution; • The Service Network Centric (SCP) solution; • The Signaling Network Centric (SG) solution; • The Access Network Centric (MS & BSC) solution. • The choice of solution(s) may impact the IMSI Migration Plan. • The preferred solution is currently the Core Network Centric solution.

10. MC/OTAF HLR/AC National Foreign Network SCP/SN Local Service Network Nat.ForeignService Network MSID Int.SS7 IMSI = IMSI_O MSC/VLR MSID Int. ForeignService Network MSID Int.C7 IMSI MSID Access Network Core Network MSID MSID Int. ForeignService Network ISG Local / Visited Network International Foreign Network IMSI Migration Plan & Subscriber Identity .3. The MSC takes care of: VLR Addressing; TCAP Signaling; SCCP Routing. Nat.SS7 SCP: Service Control Point SN: Service Node MC: Message Center OTAF: Over-The-Air Function ISG: International Signaling Gateway

11. IMSI Migration - Considerations • The implementation of an IMSI Migration Plan is an industry wide matter that requires a fare amount of ground/preparation work (e.g. the assignment of 2-digit MNCs, the programming of Mobile Station identities, the configuration of local/national/gateway/international STPs, the planning for potential MSC upgrades, the revisiting of roaming agreements, etc.). Operators should recognize the importance of early planning and validate the IMSI Migration Plan during its inception. • Furthermore, considering that the IMSI Migration process involves global considerations such as network identification, inter-network signaling and routing as well as potential impacts to national/international guidelines and standards, there may be a need for centralized coordination during the IMSI Migration planning and implementation phases.