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MIN Based IMSI and TRUE IMSI

MIN Based IMSI and TRUE IMSI. Andrew Hunter QUALCOMM Engineering Services. Overview. Acronym soup MIN, MDN, IRM, MSID IMSI_M, IMSI_T, IMSI_O, IMSI_S How does a Network tell a Mobile what to use? How does a mobile decide how to identify itself (access)

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MIN Based IMSI and TRUE IMSI

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  1. MIN Based IMSI and TRUE IMSI Andrew Hunter QUALCOMM Engineering Services

  2. Overview • Acronym soup • MIN, MDN, IRM, MSID • IMSI_M, IMSI_T, IMSI_O, IMSI_S • How does a Network tell a Mobile what to use? • How does a mobile decide how to identify itself (access) • How is mobile’s identity stored in the core (VLR) • How to address page a mobile (paging & page matching) • Summary

  3. Mobile Identification Number (MIN) MIN 1 MIN 2 MIN Digits • An MS in analog mode use a mobile identification number (MIN) and in CDMA mode use an IMSI (International MS Identity) • The MIN is a 10-digit (34-bit) number and consists of two parts • MIN1 corresponds to the least significant 7 digits (24-bits) of MIN. • MIN2 corresponds to the most significant 3 digits (10-bits) of MIN • TIA/EIA/IS-2000-6; 2.3.1

  4. Mobile Directory Number • A Mobile Directory Number (MDN) is • a dialable number associated with the mobile station through a service subscription. • A Mobile Directory Number is not necessarily the same as the mobile station identification on the air interface, i.e., MIN, IMSI_M or IMSI_T. • An MDN consists of up to 15 digits. • The mobile station has memory space to store at least one • TIA/EIA/IS-2000-5; 2.3.1.4 • Note: - Convention in the North American Numbering • Plan (NANP) often assigned MIN and MDN equal values. • - Wireless Number Portability forced this to change.

  5. Mobile Satation Identification (MSID)Meaning #1 MIN 1 MIN 2 MIN Digits • When the MIN and MDN bond was broken a new term started to be used to avoid confusion • Mobile Station ID is a MIN that cannot be assumed to be the same as the MDN • The MSID is a 10-digit (34-bit) number with the same structure as a MIN

  6. Equipment Serial Number (ESN) • Each mobile station is assigned a single electronic serial number (ESN) at time of manufacture • The ESN uniquely identifies the mobile station to any wireless system. • The ESN cannot be changed • The ESN is a 32-bit binary number • a manufacturer's identity code (8 or 14 bits) • the equipment serial number (18 bits), • For an 8 bit manufacturer code 6 bits are reserved • TIA/EIA/IS-2000-5; 2.3.2

  7. International Roaming Mobile Identification Number (IRM) MIN 1 MIN 2 MIN Digits • An International Roaming Mobile Identification Number (IRM) is • a special form of MIN • only used by countries outside of the North American Numbering Plan (NANP) • IRMs are administered by IFAST and to ensure that they are globally unique. • The IRM is a 10-digit (34-bit) number with the same structure as a MIN.

  8. International MS Identification (IMSI) Number • The IMSI consists of up to 15 numerical characters (0-9). • Mobile Country Code (MCC is the first 3 digits of the IMSI • National MS Identity (NMSI) is formed by the remaining digits. The NMSI comprises • Mobile Network Code (MNC) and • MS Identification Number (MSIN).

  9. The Class of IMSI • An IMSI can be one of two classes, 0 or 1. • Class 0 IMSI • An IMSI that is 15 digits in length - i.e. the National MS Identity (NMSI) is 12 digits in length. • Class 1 IMSI • An IMSI that is less than 15 digits in length is called a class 1 IMSI i.e. the National MS Identity (NMSI) is less than 12 digits in length) • If the MS has a class 1 IMSI, it also has an IMSI_ADDR_NUM • IMSI_ADDR_NUM is equal to the number of digits in the NMSI minus four. • A Class 1 IMSI is rarely encountered in CDMA

  10. IMSI and its various incarnations: IMSI_M, IMSI_T & IMSI_O • MIN Based IMSI (IMSI_M) • An IMSI that contains a MIN in the right-most 10 digits of the NMSI. • Can be a class 0 or a class 1 IMSI. • MIN is the forms the last 10 digits of IMSI_M (IMSI_M_S) • An unassigned IMSI_M is indicated by a 10 digit value equal to an encoding the 4 least-significant digits of the ESN with leading zeros. • True IMSI (IMSI_T) • An IMSI that is not associated with the MIN. • Can be a class 0 or class 1 IMSI. • An unassigned IMSI_T is indicated by a 10 digit value equal to an encoding the 4 least-significant digits of the ESN with leading zeros. • Operational IMSI (IMSI_O) • IMSI value the MS actually uses • Is either the IMSI_M or the IMSI_T • The choice of IMSI_O is based on • the MS assigned IMSI values • IMSI_T_SUPPORTED field of the Extended System Parameters Message

  11. The Short IMSI (IMSI_S) & its various incarnations • IMSI_S • 10-digit (34-bit) number derived from the IMSI. • An IMSI with ten or more digits has IMSI_S is equal to the last ten digits. • A 10-digit IMSI_S consists of • IMSI_S2 the most significant 3- digit part (10 bits) • IMSI_S1 the remaining 7-digit part (24 bits) • All IMSI forms have a short form • IMSI_M_S • An IMSI_S derived from IMSI_M • IMSI_M_S2 = MIN2 • IMSI_M_S1 = MIN1 • IMSI_T_S • An IMSI_S derived from IMSI_T. • IMSI_O_S • An IMSI_S derived from from IMSI_O.

  12. Mobile Country Code & IMSI_11_12 (Mobile Network Code) • Mobile Country Code (MCC) • Three digit ITU specified code identifying the home country. • Some countries have more than one MCC • Comes from the CCITT Recommendation E.212. • IMSI_11_12 • IMSI_11_12 denotes the 11th and 12th digits of the IMSI. • IMSI_T_11_12p is the programmed value for the IMSI_T • IMSI_M_11_12p is the programmed value for the IMSI_M • Mobile Network Code • A two or three digit code allocated within a MCC to a network • A two digit MNC and the IMSI_11_12 are the same thing

  13. Special or Wildcard MCC & IMSI_11_12 • MCC & IMSI_11_12 is broadcast in the Extended System Parameters Message (ESPM) • The MS stores the serving network’s MCC and MNC identity • An IMSI_M based networks can use wild card values of MCC & IMSI_11_12 • MCC received (MCCr) of all 1s i.e. ‘1111111111’ or 1023 • IMSI_11_12 received (IMSI_11_12r) of all 1s i.e. ‘1111111’ or 127 • Receiving the wildcard values means: • MS uses IMSI_M • assumes network has the same MCC and IMSI_11_12 as those of IMSI_M • TIA/EIA 95B SECTION 2.6.2.2.5 Extended System Parameters Message

  14. How the network declares to the mobile what it wants CDMA Air Interface Serving Network Mobile Station Base Station • True IMSI support is declared in the IMSI_T_SUPPORTED parameter • TMSI requirements declared in the USE_TMSI parameter • The serving network declare how the MS should identify itself by the PREF_MSID_TYPE parameter.

  15. How the MS chooses which identity to useMobile Station ID (Meaning #2!) • MS identifies itself on the Access Channel by the Mobile Station Id (MSID) • MS chooses form of MSID based on the provisioned IMSIs and the Network’s desire • MS conveys the chosen format in the MSID_TYPE parameter in access channel messages MS Addressing.xls

  16. How MS decides how much of the IMSI needs to be sent • A MS can decide to send • 15 digits – MCC + MNC + IMSI_S • 12 digits The MNC + IMSI_S only • 13 digits The MCC + IMSI_S only • 10 digits The IMSI_S only • The combination is determined by • How the network and MS values of MCC compare • How the network and MS values of IMSI_11_12 (IMSI_11_12s) compare. • Coincident values need not be included in the MSID • The combination used is declared by IMSI Class Type (IMSI_Class_0_Type)

  17. Access Today: IMSI_M MS & Network CDMA Air Interface IMSI_M Device IMSI_M Serving Network Base Station 2 1 3 4 5

  18. Access Today: IMSI_M MS & Network CDMA Air Interface IMSI_M Device IMSI_M Serving Network Base Station 2 1 3 4 5

  19. Access Today: IMSI_M MS & Network CDMA Air Interface Roaming Device Serving Network Base Station 2 1 3 4 5

  20. Mobile Identity in the IMSI_M Core MSC/VLR (Assume MCC,IMSI_11_12 = 311,28 ) Serving Network 1 Signaling Network Home Network HLR MAP 3 2 5 4

  21. IMSI_M MS & IMSI_T Network CDMA Air Interface IMSI_M Device IMSI_T Serving Network Base Station 2 1 3 4 5

  22. IMSI_M MS & IMSI_T Network CDMA Air Interface IMSI_M Device IMSI_T Serving Network Base Station 2 1 3 4 5

  23. Mobile Identity in the IMSI_T Core IMSI_M Home Network Serving Network Signaling Network 1 3 MSC/VLR (Assume MCC,IMSI_11_12 = 311,28 ) IMSI_M HLR IMSI_M MAP 2 IMSI_T Home Network IMSI_T HLR 3 4 5

  24. Page Class & Page Sub-Class • To identify the type of the page record, the base station uses • PAGE_CLASS and the • PAGE_SUBCLASS

  25. Page Matching

  26. Page Matching

  27. Paging: IMSI_M MS & Network, Wildcard MCC/MNC CDMA Air Interface Roaming Device Serving Network MSC/VLR (Assume MCC=310 & IMSI_11_12 = 00 ) Base Station 1 2 3 3 4 5

  28. Paging: IMSI_M MS & Network CDMA Air Interface Roaming Device Serving Network MSC/VLR Base Station 1 2 3 3 4 5

  29. Paging: Non-Unique MIN based IMSI & Wildcard MCC/MNC CDMA Air Interface Roaming Device Serving Network MSC/VLR Base Station 1 2 3 3 4 5

  30. Paging: IMSI_M MS & Network, Wildcard MCC/MNC CDMA Air Interface Roaming Device Serving Network MSC/VLR Base Station 1 2 3 3 4 5

  31. Summary • MIN Based IMSI • MIN part can be used to identify an HLR • MCC/MNC part can be non unique • With properly configured MCC/MNC then MIN based IMSI can be used as a TRUE IMSI • TRUE IMSI • MSIN part can never be relied upon to identify HLR • MCC and MNC parts must be used as part of the routing • Both will coexist during any transition • Vendors are considering solutions • Operators may want to communicate their requirements on this issue

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