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Тема: IMSI & True IMSI

  1. #1
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    IMSI & True IMSI

    Может кто знает, чем отличаются IMSI и True IMSI, какие особенности применения, может у кого мануалы есть?

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    Это есть в стандарте IS-95

    Mobile stations operating in the analog mode are identified by the mobile identification number (MIN) (see 2.3.1).
    Mobile stations operating in the CDMA mode are identified by the International Mobile Station Identity (IMSI).. Mobile Stations shall have two different identifiers, IMSI_T and IMSI_M. The IMSI consists of up to 15 numerical characters (0-9). The first three digits of the IMSI are the Mobile Country Code (MCC), and the remaining digits are the National Mobile Station Identity (NMSI). The NMSI consists of the Mobile Network Code (MNC) and the Mobile Station Identification Number (MSIN). The IMSI structure is shown in Figure 6.3.1-1.


    Figure 6.3.1-1. IMSI Structure

    An IMSI that is 15 digits in length is called a class 0 IMSI (the NMSI is 12 digits in length); an IMSI that is less than 15 digits in length is called a class 1 IMSI (the NMSI is less than 12 digits in length).
    IMSI_M is an IMSI that contains a MIN in the lower ten digits of the NMSI. An IMSI_M can be a class 0 or a class 1 IMSI. If the IMSI_M is not programmed, the mobile station shall set the four least-significant digits of the IMSI_M to the value of the ESNp, converted directly from binary to decimal, modulo 10000. The other digits shall be set to 0.
    IMSI_T is an IMSI that is not associated with the MIN assigned to the mobile station. An IMSI_T can be a class 0 or class 1 IMSI. If the IMSI_T is not programmed, the mobile station shall set the four least-significant digits of the IMSI_T to the value of the ESNp, converted directly from binary to decimal, modulo 10000. The other digits shall be set to 0.
    When operating in the CDMA mode the mobile station shall set its operational IMSI value, IMSI_O, to either the IMSI_M or the IMSI_T depending on the capabilities of the base station (See 6.6.2.2.5).
    An IMSI_S is a 10-digit (34-bit) number derived from the IMSI. When an IMSI has ten or more digits, IMSI_S is equal to the last ten digits. When an IMSI has fewer than ten digits, the least significant digits of IMSI_S are equal to the IMSI and zeros are added to the most significant side to obtain a total of ten digits. A 10-digit IMSI_S consists of 3- and 7-digit parts, called IMSI_S2 and IMSI_S1, respectively, as illustrated in Figure 6.3.1-2. IMSI_S is mapped into a 34-bit number (see 6.3.1.1). The IMSI_S derived from IMSI_M is designated IMSI_M_S. The IMSI_S derived from IMSI_T is designated IMSI_T_S. The IMSI_S derived from IMSI_O is designated IMSI_O_S.
    The mobile station shall have memory to store the 34-bit IMSI_M_Sp and the 34-bit IMSI_T_Sp. IMSI_M_Sp is represented by the 10-bit IMSI_M_S2p and the 24 bit IMSI_M_S1p. IMSI_T_Sp is represented by the 10-bit IMSI_T_S2p and the 24 bit IMSI_T_S1p.


    Figure 6.3.1-2. IMSI_S Binary Mapping

    When an IMSI has 12 or more digits, IMSI_11_12 is equal to the 11th and 12th digits of the IMSI. When an IMSI has fewer than 12 digits, digits with a value equal to zero are added to the most significant side to obtain a total of 12 digits and the IMSI_11_12 is equal to the 11th and 12th digits of the resulting number.
    IMSI_11_12 is encoded as described in 6.3.1.2. The mobile station shall have memory to store the 7-bit IMSI_M_11_12p and the 7-bit IMSI_T_11_12p.
    The 3-digit MCC is encoded as described in 6.3.1.3. The mobile station shall have memory to store the 10-bit MCC_Mp and the 10-bit MCC_Tp.
    If the mobile station has a class 1 IMSI_T, or IMSI_M, it shall have memory to store IMSI_T_ADDR_NUMp and IMSI_M_ADDR_NUMp. IMSI_T_ADDR_NUMp is equal to the number of digits in the NMSI minus four. IMSI_M_ADDR_NUMp is equal to the number of digits in the NMSI of the IMSI_M minus four.
    6.3.1.1 Encoding of IMSI_M_S and IMSI_T_S
    The IMSI_M_S and IMSI_T_S binary mapping is defined as follows:
    1. The first three digits of the IMSI_M_S and the first three digits of the IMSI_T_S are mapped into ten bits (corresponding to IMSI_M_S2p and IMSI_T_S2p, respectively) by the following coding algorithm:
    a. Represent these three digits as D1 D2 D3 with the digit equal to zero being given the value of ten.
    b. Compute 100  D1 + 10  D2 + D3 - 111.
    c. Convert the result in step b to binary by the standard decimal-to-binary conversion as described in Table 6.3.1.1-1.

    Table 6.3.1.1-1. Decimal to Binary Conversion Table
    Decimal Number Binary Number
    0 0000000000
    1 0000000001
    2 0000000010
    3 0000000011
    4 0000000100
    • •
    • •
    • •

    998 1111100110
    999 1111100111

    2. The second three digits of IMSI_M_S and the second three digits of IMSI_T_S are mapped into the ten most significant bits of IMSI_M_S1p and IMSI_T_S1p, respectively, by the coding algorithm described in 1.
    3. The last four digits of IMSI_M_S and the last four digits of IMSI_T_S are mapped into the 14 least significant bits of IMSI_-M_S1p and IMSI_T_S1p, respectively, as follows:
    a. The thousands digit is mapped into four bits by a Binary-Coded-Decimal (BCD) conversion, as specified in Table 6.3.1.1-2.
    b. The last three digits are mapped into ten bits by the coding algorithm described in 1.

    Table 6.3.1.1-2. BCD Mapping
    Decimal Digit Binary Number
    1 0001
    2 0010
    3 0011
    4 0100
    5 0101
    6 0110
    7 0111
    8 1000
    9 1001
    0 1010

    The following example illustrates the IMSI_-T_S2p and IMSI_T_S1p calculation procedure. Let the IMSI_T be the 9-digit number 123456789. Since the IMSI_T has fewer than ten digits, the nine least significant digits of the IMSI_T_S are equal to the IMSI_T digits and the most significant IMSI_T_S digit is set to zero. So the 10-digit IMSI_T_S is 012 345 6 789. IMSI_T_S2p and IMSI_T_S1p are calculated as follows:
    • IMSI_T_S2p. The ten-bit IMSI_T_S2p is derived from the first three digits of the IMSI_T_S (i.e., 012):
    a. D1 = 10; D2 = 1; D3 = 2.
    b. 100  D1 + 10  D2 + D3 - 111 = 100  10 + 10  1 + 2 - 111 = 901.
    c. 901 in binary is ‘11 1000 0101’.
    Therefore, IMSI_T_S2p is ‘11 1000 0101’.
    • IMSI_T_S1p. The ten most significant bits of IMSI_T_S1p are derived from the second three digits of the IMSI_T_S (i.e., 345):
    a. D1= 3; D2 = 4; D 3 = 5.
    b. 100  D1 + 10  D2 + D3 - 111 = 100  3 + 10  4 + 5 - 111 = 234.
    c. 234 in binary is ‘0011 1010 10’.
    The next four most significant bits of IMSI_T_S1p are derived from the thousands digit of the IMSI_T_S (i.e., 6) by BCD conversion: 6 in BCD is ‘0110’.
    The ten least significant bits of IMSI_T_S1p are derived from the last three digits of the IMSI_T_S (i.e., 789):
    a. D1 = 7; D2 = 8; D3 = 9.
    b. 100  D1 + 10  D2 + D3 - 111 = 100  7 + 10  8 + 9 - 111 = 678.
    c. 678 in binary is ‘10 1010 0110’.
    Therefore, IMSI_T_S1p is ‘0011 1010 1001 1010 1010 0110’.
    6.3.1.2 Encoding of IMSI_M_11_12 and IMSI_T_11_12
    The IMSI_M-_11_12 and IMSI_T_11_12 binary mapping is defined as follows:
    1. Represent the 11th digit as D11 and the 12th digit as D12 with the digit equal to zero being given the value of ten.
    2. Compute 10  D12 + D11 - 11.
    3. Convert the result in step 2 to binary by a standard decimal-to-binary conversion as described in Table 6.3.1.1-1 and limit the resulting number to the 7 least significant bits.
    6.3.1.3 Encoding of the MCC_M and MCC_T
    The MCC_M and MCC_T binary mapping is defined as follows:
    1. Represent the 3-digit Mobile Country Code as D1 D2 D3 with the digit equal to zero being given the value of ten.
    2. Compute 100  D1 + 10  D2 + D3 - 111.
    3. Convert the result in step (2) to binary by a standard decimal-to-binary conversion as described in Table 6.3.1.1-1.
    6.3.1.4 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 should have memory to store at least one Mobile Directory Number (see Table F.3-1).

  3. #3
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    Спасибо, буду разбираться

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