You most likely use it every day, yet if someone asked you how it works, you’d have a hard
time explaining it. I’m not talking about Physics here, it’s all about your SIM card,
that little chip in your phone. So let’s figure it out!
When was it invented?
First of all, have you ever wondered what SIM stands for? It actually means subscriber
identity module or subscriber identification module. The first SIM card in the world was developed
in 1991 by the German company Giesecke & Devrient. They sold 300 SIM cards to Radiolinja, a Finnish
wireless network operator. In 1992, they sold the first GSM mobile phone with a SIM card;
it was a Nokia 1101. Today, it’s hard to find a person who’s never used a SIM card
– over 7 billion gadgets around the world use them to make calls, send SMS and surf
the web. Experts predict this number is going to grow to 20 billion in the near future.
The European Telecommunications Standards Institute (ETSI) still holds the most SIM
patents, but other private phone companies also have some important patents thanks to
which SIMs work. The largest manufacturer of SIM cards in the world is the Gemalto company,
with headquarters in Amsterdam and 15,000 employees. They’re now working towards the
mass production of SIMs for 5G networks. The first SIM cards cost more than one dollar
each to manufacture. Today, they’re basically worth a few cents apiece. But that price doesn’t
cover design, development, inserting chips into plastic cards and shipping them.
Why do I need a SIM card?
A SIM card has unique identification information on it, like what mobile network it belongs
to. It’s called an IMSI -International Mobile Subscriber Identity. This unique ID connects
your phone number with your gadget. When someone is dialing your number, the call will go to
the exact phone you have at the moment. SIM also has its own memory. Even though it’s
really small – just 64 kilobytes – it can store around 250 contacts and some SMS.
By the way, the same memory was in the Apollo Guidance Computer used for the first Moon
landings.
If your SIM card is mobile, meaning you can remove it and put it back into your phone
yourself, you can also use it on different phones. This comes in handy when your own
gadget’s battery is dead, and you desperately need to make a phone call from your number.
Can my phone work without a SIM card?
Technically it can, as a camera, or a device that connects you to Wi-Fi, but not as a phone
to make calls or text someone. For the absolute majority of phones, a gadget without a SIM
card is like a human without a brain. The good news is, even if you seriously damaged
your phone - smashed your screen or bent the casing - you could still use the same phone
number and keep your contacts. All it takes is a SIM card transplantation.
How does a SIM card work? A SIM card basically looks like a little piece
of plastic. It has an even smaller chip inside that is its Microcontroller. It’s made out
of silicone and plated with gold or other metals to help it keep contact with the phone.
The chip contains a processor, memory and security circuits. Your mobile device reads
the chip when you stick the SIM in it. It contains the operating system for the card,
can do some basic math, and stores important information. This information is put on the
chip on the production line. The most basic types of that information are your International
Mobile Subscriber Identity and a 128-bit key called Ki (Key Identification). Those are
basically your login and password in the mobile phone world. All messages from your phone
to the network are in a secret code. The key to encrypt and decrypt messages is also stored
on the SIM card. This provides communication privacy. The SIM card chip also stores specific
data, such as your card’s unique serial number, the name of your cellular carrier,
your PIN (if you’ve ever wondered what it stands for, by the way, it’s your Personal
Identification Number) to lock and unlock the phone, PUK code from the carrier to unblock
the phone and much more. Even your contacts and last dialed numbers are there.
Can someone track my location with the help of a SIM card?
This is a question of both privacy and security. While it’s creepy to think someone can track
your physical location for their purposes, it’s good to know your phone can be found
when it’s lost or stolen. And, it can also be helpful when it concerns lost kids or elderly
people, for example. So, a SIM card can help to establish your location, but it’s only
one player in the “find me” game. When you insert a SIM in your cell phone, tablet,
or even car, and turn the device on, it starts connecting to cell towers to catch the signal.
As you move around, your SIM works with the towers nearest to you to provide the strongest
signal. All these towers have known physical locations. When phone companies or the police
use their algorithms to find out how strong the signal is from this or that tower, they
can narrow down the search area significantly. Services like “Find my phone” also use
WiFi data to know a more specific location. Of course, it’ll only work when the WiFi
on your gadget is on. Add GPS information to this, and you’ll get fairly accurate
data on any gadget’s whereabouts in real time. GPS will only be handy in this situation
when you have cellular data enabled on your plan or gadget. So if you want complete privacy,
turn it off, along with WiFi, and tracking you down using information from your SIM alone
will be a challenge. Do SIM cards break?
SIM cards, like just about anything on this planet, can get damaged or broken and don’t
last forever. You’ll be the first to know when that happens, as your phone will inform
you the chip is defective. You won’t be able to connect to your cellular provider
in this case. Water is unlikely to be the reason for that damage, though, since basically
all new phones have sealed ports and jacks. The SIMs themselves have always been waterproof.
Why are SIM cards getting smaller? The first SIM cards were around the same shape
and size of a credit card. They worked fine with the first mobile phones, but as mobile
technology evolved and phones got smaller, the SIM cards clearly needed improvement,
too. Imagine fitting a credit card into an iPhone – not the best idea, right? So fortunately,
SIMs became smaller and more powerful at the same time. First came the standard thumbnail-sized
SIMs. They were standard until 2010, when the Micro-SIM became universal. But even that
SIM still had too much useless plastic. Some people who upgraded their phones cut out the
most important part with basic tools like scissors. It was pretty risky since damaging
the chip even a bit could ruin it all. In 2012, Nano-SIMs came into play, which are,
in essence, just little chips with no extra plastic around them. If you ever need to insert
a newer generation SIM in an older phone, there are special adaptors for that.
The future of SIM cards The latest iPhone models give you an idea
of what all SIM cards will be like in the future. They’ll be “eSIM”s, which means
embedded SIM cards. Their size will be just a fraction of a Nano-SIM. Forget the huge
pieces of plastic and scissors you used to cut out the chips! In fact, there’ll be
no physical SIM cards whatsoever – instead, they’ll be tiny chips on your phone’s
logic board. The information on the chip will be rewritable, so you’ll be able to change
your carrier with a few easy steps. eSIMs will be cloud-based, super secure, super fast
and convenient to use. It’ll also be a win-win situation for the manufactures: less distribution
and installation costs, and better design with more free physical space on your gadget!
Losing one slot on your phone is also great because it will ensure extra protection from
water and dust getting inside.
So, the new iPhones already have two SIM-cards: one of the old school physical type and the
other – an e-SIM that you can use with any carrier you like.
At what age did you get your first cell phone? Let me know down in the comments! If you learned
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