TECHNOLOGY – The SIM turns 30: that’s how it was before it became the cards we know today

This year 2021 marks three decades since the launch of the world’s first commercial SIM card, created by the German security technology group Giesecke + Dvrient (G + D), which gave it to a Finnish telecommunications company to start selling it.

Despite being 1991 the year in which this type of cards began to be used, the technologies that support it were developed several years before their arrival on the market. The G + D company registered the first patent in 1968.

Later, in 1989, these plug-in and interchangeable SIM cards were defined and standardized, and in 1990 a milestone occurred with the introduction of the SIM Toolkit standard. This allowed to extend the functions between the card and a GSM phone (acronym for Global System Mobile).

The SIM is made up of a microprocessor and an operating system that provide secure access to the mobile network. Although it is true that, at first, its size was like that of a credit card, over time it has undergone a process of transformation of its dimensions: from mini to nano SIM.

In order to use these chips, GSM networks are necessary and these, in turn, require a way to identify users through their phone number and device in order to make and receive calls.

Thus, the SIM cards include the identification number of the local area and its password, as well as the operator data necessary to be able to be in contact with other users, either by voice calls or by short messages (SMS).

In addition, they have the ability to save these messages and the device’s contact book, so that when switching to another mobile, it is possible to recover all the phones that have been recorded in it.


Over time, SIM cards have been transformed, adapting to the devices that host them and becoming smaller and smaller. Depending on the age of the phone, we can find them in different sizes.

The original SIMs, similar in size to a credit card, are no longer used. They were large (85.6 x 55.98 millimeters) and had little capacity for storing contacts or messages. Its successor was the miniSIM, which is now known as SIM.

Its standard format was 25×15 millimeters and it fit in all devices. However, in 2003 an even smaller card, microSIM, 15×12 millimeters, was developed. Much of its plastic covering was removed, leaving only the chip.

The last to reach most smartphones was the nanoSIM, which was even smaller (12.3 x 8.8 millimeters). It was in 2012 when it was implemented in almost all phones and with it manufacturers could optimize the space of the ‘hardware’ of the devices. With this evolution, their ability to store information also grew.

Currently, most technology manufacturers choose to create phones with the MultiSIM option, that is, they offer the possibility that users can use a single terminal with several of these cards, which translates into different phone numbers that coexist in a device.


The introduction of eSIM (or embedded SIM) technology in 2012 was another milestone in the technology field as the SIM profile was allowed to be downloaded to the device thereafter. This opened a new range of possibilities for digitization and logistics optimization.

To do this, a generic SIM module as a permanent chip called eUICC (Universal Integrated Circuit Card) is installed in the device. Its customization is done remotely by providing, via mobile communications or a local area network (WLAN), data from network operators.

Because of this, It is increasingly common for manufacturers of ‘smartphones’, tablets or smart watches to present more frequently equipment that has eSIM technology. In parallel, eSIM technology continues to evolve in the field of iUICCs, better known as embedded SIMs.

These are a tamper-proof element (TRE) inside a SoC (system on a chip), so that the SIM is no longer an insertable ‘hardware’ module as it was before, but forms a single connectivity module.

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