What is SIM ?

According to the International Card Manufacturers Association (ICMA), there were 5.4 billion SIM cards manufactured globally in 2016 creating over $6.5 billion in revenue for traditional SIM card vendors

A SIM card is internationally identified by its Integrated circuit card identifier (ICC-ID), which is engraved on the body of the card. It is also identified by the carrier with its International mobile subscriber identity (IMSI)

SIM cards are one of the constant components in a phone. No matter how new or advanced a phone model may be, there’s no way of securing a line during the registration process without the chip.

The rise of cellular IoT and 5G networks is predicted to drive the growth of the addressable market for SIM card manufacturers to over 20 billion cellular devices by 2020.

Essentially, these two numbers tell the carrier that your phone is allowed to operate on its network and, once connected, should be billed for certain features. Beyond identification, SIM cards have several other functions.

There are a couple of facts that are relatively unknown about the SIM card, the little thing that would send us into a frenzy when it’s not working.

SIM cards have evolved a lot over the years. While they have maintained a relative thickness of just under 1mm, their surface area has steadily decreased, from the credit card-sized plates used in the earliest cellphones to the nano SIMs of today's devices.

No lah, it doesn’t stand for Singapore Institute of Management. That one is a school in Clementi.

The introduction of Embedded SIM (eSIM) and Remote SIM Provisioning (RSP) from the GSMA may disrupt the traditional SIM card ecosystem with the entrance of new players specializing in "digital" SIM card provisioning and other value-added services for mobile network operators.

The nano SIM is the SIM card's fourth size standard since its inception. Designated as 4FF, or fourth form factor, it measures 12.3mm x 8.8mm x 0.67mm, a reduction of over 42 times from the SIM's inception.

SIM is the short term for subscriber identity module. Wah, sounds so technical suddenly! But what does it all embody, and what is its function about?

Most people, however, are more familiar with the 2FF SIM card, known more readily as the Regular SIM card. At 25mm x 15mm x 0.76, it is 3.4 times larger than today's current SIM cards, which offer the same features in a much more compact package. Some manufacturers still choose to use the micro SIM format which, at 15mm x 12mm, is only slightly larger than the nano SIM.

There are three operating voltages for SIM cards: 5 V, 3 V and 1.8 V (ISO/IEC 7816-3 classes A, B and C, respectively). The operating voltage of the majority of SIM cards launched before 1998 was 5 V. SIM cards produced subsequently are compatible with 3 V and 5 V. Modern cards support 5 V, 3 V and 1.8 V.

Now here’s the kicker. The reason why Singtel or StarHub or M1 (or any other communications company for that matter) have this chip installed onto your phone when you subscribe with them is so that they can identify you and also authenticate you as a user on their very vast network.

Many carriers offer branded SIM cards with cutouts for all three modern sizes, so users can choose which version they want to insert depending on their device.

It’s also easy to use; if you switch to another phone, all you have to do is change your SIM from your old phone to your new one.

Modern SIM cards allow applications to load when the SIM is in use by the subscriber.

There are also adapters so nano SIM cards can fit into slots meant for micro SIM or Regular SIM cards.

Also, when your subscriber needs to bill you by your number, it just makes everything much simpler la. This one for sure you know!

These applications communicate with the handset or a server using SIM Application Toolkit, which was initially specified by 3GPP in TS 11.14. (There is an identical ETSI specification with different numbering.)

Once upon a time, a SIM card used to have plates the size of your current credit card. No, I’m serious, you lucky young fellows. Here, take a look:

Often, a SIM card is provided with the purchase of a phone by your carrier and it is used to store data about your account. Because it has a small amount of memory and a very low-powered processor, the SIM card not only enables communication between the phone and its carrier, but stores information such as phone numbers, security data and more.

ETSI and 3GPP maintain the SIM specifications. The main specifications are: ETSI TS 102 223, ETSI TS 102 241, ETSI TS 102 588, and ETSI TS 131 111.

Thankfully it has evolved and become more compact AND powerful. There are a couple of manufacturers who still use the micro-SIM size, but in actuality it’s just a teensy bit bigger than a nano-SIM.

In recent years, carriers have begun using specialized SIM cards with so-called Secure Elements to store credit card credentials in order to facilitate mobile payments.