CODEWITHSUNDEEP
filesystemsgsmapdusim-card
M. Sh
M. Sh

Reputation: 123

Updating MSISDN on the SIM card

I'm trying to create/understand APDU content for updating EFmsisdn file on a USIM, as stated in ETSI TS-131102, section 4.2.26 the content of the file is as follows:

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I have the following valid ISO-7816 command for selecting the file and updating the first record: 00A4090C047FFF6F4000DC010422FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF06815545443333FFFFFFFFFFFFFF

What I don't understand is the number of fillers (0xFF). In the table, it says 1 to X bytes for alpha identifier. What is the alpha identifier and how can I know the length?

I appreciate any hint.

Upvotes: 0

Views: 1690

Answers (1)

QuickPrototype
QuickPrototype

Reputation: 883

My understanding is that EFmsisdn follows a similar convention to EFadn.

To answer your question:

  1. What is the alpha identifier? It is a text identifier for the number. So in a phonebook it will be the name of the contact. Some operators may set this to "My Number" for example.

  2. You can get its length by using the total length of the returned result and subtracting the 14 fixed Mandatory bytes.

For a little more info checkout EFadn in TS 131 102.

Upvotes: 1

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