All you ever wanted to know about the SIM card

Hands up if you’ve ever heard of the SIM card. Yes, we see that all of you are reaching for the sky.

Now, hands up if you know what SIM stands for. Chances are, there aren’t many hands left up. Even though SIM cards have been by our side since the time we owned our first mobile phones, there is precious little we know about them (including the tidbit that SIM stands for Subscriber Identity Module).

This is a pity because this fundamental piece of technology has enabled us to store our contacts, make calls, and send text messages over the decades. So if you want to stop taking it for granted and learn about the history of the SIM card, you’ve come to the right place!

Mobile phones pre-SIM

Mobile phones existed before SIM, but not in a way that we’re familiar with today. In 1973, the first handheld mobile phone call was made with a phone that was dubbed a “brick” because of its heft.

A decade later, the first commercial mobile phone was launched by Motorola, costing US$4,000 for the handset alone!

Evolution of SIM card – smaller yet mightier

As its name suggests, a Subscriber Identity Module is used to identify and authenticate you, the subscriber. It was developed in 1991 by German Smart Card Maker Giesecke+Devrient for Finnish Network provider, Radiolinja, and was based on the specifications previously set by the European Telecommunications Standards Institute (ETSI). It stored subscriber information – including the associated phone number – in a circuit embedded in a plastic card. Just as importantly, it is what enables your device to connect to a mobile network, through which you can make calls, send text messages, and go online.

This first iteration of the SIM card was as large as a credit card, which wasn’t too out of the world for its time as mobile phones were way bigger back then. The SIM card was where you stored the names and contact numbers of your family and friends, as well as SMS messages (remember those?).

The earliest versions of SIM cards were able to store a whopping five SMS messages and 20 contacts. Remember, this was the early 90s, where you had to carry a (paper) notebook and write down phone numbers or memorise them, so 20 contacts was life-changing.

In 1996, the SIM card shrank in size dramatically, becoming known as the mini-SIM. About the size of the top portion of your thumb, it usually fitted in a nook behind the battery of mobile phones (this was the era when Nokia was the top mobile dog and removable batteries were a thing).

The mini-SIM continued to be the standard for the next decade and a half until 2010, when the micro-SIM – about the size of your thumb’s nail – took its place. In just two short years, the micro-SIM itself was replaced by the nano-SIM, which was just the size of your pinkie’s nail. By that time, SIM cards could store over 250 contacts.

Rise of the eSIM

In today’s world, SIM cards are no longer just for mobile phones. The Internet of Things means that a myriad of electronics, from everyday appliances like refrigerators to gizmos like drones, need connectivity. This is where eSIMs, or embedded SIMs, come in.

They are basically the circuitry of a SIM card soldered into the device itself, so an extra slot is not needed. This is especially valuable for smaller gadgets like smartwatches where space is of the essence.

The eSIMs can also be remotely reprogrammed to change their mobile service plans or providers, enabling a bunch of devices to be managed in one go. If you have a large space outfitted with CCTV cameras that have eSIMs, you won’t have to go to each one of them one by one in order to swap out SIM cards to change mobile providers.

The same goes for mobile phones with eSIMs. You can use two different lines on the same phone without having to physically pop out one SIM card and pop in another. For instance, certain models of the iPhone support two active eSIMs at the same time or one nano-SIM with one eSIM.

Of course, the downside is that if your mobile device breaks down, you can’t just take out your SIM card and slide it into a replacement device.

What’s next, the pico-SIM?

The eSIM has not caught on in a widespread way in Singapore yet, but tech tastes are always evolving so don’t count it out yet.

Or who knows, maybe the physical SIM card will undergo yet another downsizing and we’ll all be using pico-SIMs soon.

Our reliance on mobile networks will only continue to increase as more devices need connectivity, so stay tuned for the next iteration of the SIM!