d-chips

File Identifier

The file identifier (FID) is used to address or identify each specific file. Unlike filename in modern computer, the FID consists of two bytes and shall be coded in hexadecimal notation.

The first byte of FID identifies the type of file:

This article describes the Logical Model of a SIM Card File System according to 3GPP TS 11.11 which you can download for free here. The File Selection and Read/Write Data will be discussed on another post.

So, have you ever wonder how SIM card organizes data inside it? Actually, SIM cards organizes data just like modern computers! Wow?? Well... actually with limitations.

GSM 7 bit Default Alphabet

Back to old school times, we studied the alphabet before learning words and other things. The same rule also applies in GSM world. The GSM has its own set of alphabet: some characters are similar to ASCII some others are not. You can get the specification (3GPP TS 03.38) freely here. So let's start learning!

Coding of Alpha fields in the SIM for UCS2

This article discusses about the alpha field coding used by SIM card to display UCS2 on Mobile Equipment's display (phone's display).

Alpha fields? UCS2? What are they? Okay let's start by learning the definitions...