8.150 Alternative IMSI
29.2743GPP3GPP Evolved Packet System (EPS)Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C)Release 18Stage 3TS
Alternative IMSI is transferred via GTP tunnels. The sending entity copies the value part of the Alternative IMSI into the Value field of the Alternative IMSI IE. Alternative IMSI is in the form of an IMSI as defined in 3GPP TS 23.003 [2].
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Bits |
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Octets |
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
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1 |
Type = 219 (decimal) |
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2 to 3 |
Length = n |
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4 |
Spare |
Instance |
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5 |
Number digit 2 |
Number digit 1 |
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6 |
Number digit 4 |
Number digit 3 |
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… |
… |
… |
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n+4 |
Number digit m |
Number digit m-1 |
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Figure 8.150-1: Alternative IMSI
Octets 5 to (n+4) represent the Alternative IMSI value in international number format as described in ITU‑T Rec E.212 [64], encoded as TBCD digits, i.e. digits from 0 through 9 are encoded "0000" to "1001". When there is an odd number of digits, bits 8 to 5 of the last octet are encoded with the filler "1111". The maximum number of digits is 15.