Integrated Circuit Card SIM

Description

The term 'IC card SIM' is an obsolete designation for the ID-1 SIM, which is the original full-size SIM card format standardized in early GSM specifications. The ID-1 SIM has the dimensions of a standard credit card (85.6 mm × 53.98 mm × 0.76 mm) and was the first form factor used for SIM cards when they were introduced in the early 1990s. The term 'IC card SIM' was used to distinguish this card type from other IC card applications, but it has since been deprecated in favor of more specific terms like 'ID-1 SIM' or simply 'SIM card'.

In the context of 3GPP, the term appears in TS 21.905, which is the vocabulary specification. The definition states it is an obsolete term for ID-1 SIM. This indicates that the term was once used but is no longer recommended for new specifications. The ID-1 SIM itself is largely obsolete in modern mobile networks due to its large size; it has been replaced by smaller form factors such as plug-in SIM (25 mm × 15 mm), micro-SIM (15 mm × 12 mm), and nano-SIM (12.3 mm × 8.8 mm). However, the ID-1 form factor is still used in some legacy systems and for certain applications where a larger card is acceptable.

The IC card SIM, as a concept, represents the early integration of the SIM application into an IC card. It provided the same security functions as modern SIMs: storage of the IMSI, authentication key Ki, and execution of the AKA algorithm. The physical size was a constraint for early mobile phones, which were bulky, but as devices miniaturized, the SIM shrank accordingly. The term 'IC card SIM' thus reflects a historical stage in the evolution of SIM technology.

From a technical perspective, the ID-1 SIM operates according to ISO/IEC 7816 standards for contact smart cards. It has eight contact pads (though only a few are used) and communicates with the ME via a serial interface. The card contains a microprocessor and memory, and it runs a card operating system that manages the SIM application. Despite its obsolescence, the ID-1 SIM is still referenced in some test equipment and legacy documentation.

The term 'IC card SIM' has not undergone any definitional changes across Releases 4 to 19; it has consistently been marked as obsolete. This stability indicates that the term is frozen and will likely remain as a historical note in the vocabulary. Engineers should use 'ID-1 SIM' or 'SIM card' instead to avoid confusion.

Purpose & Motivation

The term 'IC card SIM' existed to provide a clear reference to the original SIM form factor, which was based on the ID-1 card size. In the early days of GSM, SIM cards were the size of credit cards, and the term 'IC card SIM' helped distinguish them from other types of IC cards, such as bank cards or ID cards. As technology advanced and smaller form factors were introduced, the need for this term diminished, and it became obsolete.

The purpose of the term was also to align with international standards for IC cards, particularly ISO/IEC 7816, which defines the physical and electrical characteristics of smart cards. By using 'IC card SIM', specifications could refer to a SIM that conformed to these standards. However, as the SIM evolved into smaller plug-in formats, the term became less relevant, and more precise terms like 'plug-in SIM' and 'ID-1 SIM' were adopted.

The obsolescence of 'IC card SIM' reflects the broader evolution of mobile devices towards miniaturization. The ID-1 SIM was simply too large for modern handsets, and its replacement by smaller cards was driven by user demand for sleek devices. Today, the term serves only as a historical marker in 3GPP vocabulary, reminding engineers of the origins of SIM technology. Its existence in the glossary helps prevent confusion when reading older specifications.