Smartphones are an irreplaceable component of our daily lives. They facilitate mobile communication and allow users to stay in touch from anywhere around the globe. But have you wondered what actually enables mobile phones to function? It is undoubtedly a SIM Card that empowers your device to communicate with each other. But what is a SIM? How does it work? Is it really so important? If you are someone who wonders about these questions, then you are at the right place. Let us scroll down and explore the most popular FAQs regarding a SIM card.
What is a SIM Card?
Let us begin with addressing the elephant in the room: what is a SIM Card? A SIM, also known as a Subscriber Identity Module, is a small plastic chip that fits in your mobile phone to facilitate communication. It is this chip that allows users to make calls, send SMSs, and connect to the internet. A SIM Card also holds data such as a unique ID or the International Mobile Subscriber Identity (IMSI), which allows you to connect to a phone user.
The SIM is one of the most popular techs of the 21st century. Without it, mobile communications would have been a fantasy. In fact, many new techs and web services rely on SIM cards, such as m-banking and mobile payments. Hence, it is paramount that one knows how this marvelous piece of tech works.
How does it work?
We can imagine a SIM to be the telecom credential that authenticates you with the network carrier and allows you to use the mobile communication network via a mobile device. And basically, that’s how the SIM works. We have explained the same process in detail, such as:
- First, the user inserts a SIM into a mobile phone.
- The device then registers the SIM and obtains the IMSI that is on the SIM card.
- Then, the device tries to connect to the network carrier. The network carrier information is also on the SIM.
- After connecting to the network, the device initiates the authentication process, where it exchanges the IMSI with the carrier.
- If the same information is found valid in the carrier’s records, the network provider assigns your device and the inlaid SIM with a Ki (A 128-bit value used in authenticating the SIM card).
- After assigning the Ki, the network operator generates a random number, relays it to the device, and in turn to the SIM, using GSM cryptography algorithm for computing the SRES_2.
- After which, another unique number is generated and relayed back and forth to the operator and the SIM card.
- Finally, the SIM uses the same algorithms and the second unique number to generate the third and final number.
- Upon matching, the SIM gets legitimized and granted access to the network.
- Once your SIM has been authenticated, you can use it on any device.
What are the different SIM card formats currently used?
With technological development, SIM cards also have developed and changed. Today we use three types of SIM cards, Standard, Micro, and Nano. Although there is yet another type, the e-SIM, it is not that widespread.
A Standard SIM card is the biggest one out of the group at 85 mm x 53 mm, whereas the Micro SIM is much smaller at 15 mm x 12 mm. However, a Nano SIM card is the smallest one at 12.3 mm x 8.8 mm. Due to different sizes, these SIM cards get used in various devices. As for the e-SIM, it comes embedded into the smartphone and is reprogrammable, hence forgoing the need for removal. Reportedly, an e-SIM sports dimensions of 6 mm x 5 mm. But the best part about SIM cards is no matter the size, the information one chip holds is actually the same all across the board.
Top FAQs regarding SIM Cards
Now, let us begin with the top FAQs regarding a SIM card:
What is the purpose of a SIM card?
The sole purpose of a SIM is to facilitate mobile communication. The network carrier sells SIM cards that have IMSI or IMEI on them, which the provider uses to authenticate SIM users and offer services. The SIM Card is the bridge between the hardware and the network carrier.
Will a mobile device work without a SIM?
Of course, it will, but not as it was intended. Meaning, a mobile phone was invented primarily for mobile communication. However, the rapid advancement of tech has brought us the wonders of smartphones that do much more than simple calling. They are almost a computer. And since these smartphones come with Wi-Fi receivers, users can still connect to the net and chat or call using modern communication services such as VoIP or IM. SIM cards are not that important to a smartphone if you think about it. In fact, there are specific devices that are smartphones without a SIM; We call them Tablets. But if you want to enjoy the benefits of a cellular network, there is still no recourse other than a SIM.
Are SIM cards traceable?
Yes, SIM cards can aid with tracking. SIM card location is visible when it connects to a cellular tower. Thus using tower triangulation, one can approximately figure out your general physical location. And then there is GPS which uses the internet to connect to a satellite, providing more geographical information. When both get combined, a fairly accurate location can be found using a SIM card.
What is a SIM Profile?
A profile is something that encompasses data from your network provider, related to the services you are currently using. It allows the carrier to keep track of the services they ought to provide, the balance amount, dues, and other administrative functionalities.
Can I use a SIM on multiple devices?
Yes, as long your SIM has been authenticated with the network carrier, you can use it on any supported device. The only requirement is the slot size on the device, but users can easily cut their SIM to fit the device or use a SIM expander or adaptor to increase the size.
What data does a SIM Card store?
SIM cards generally contain a lot of unique data that helps with authentication and service. These data are IMSI/IMEI, your phone number, the network carrier’s information, PUK, Ki, contacts, etc.
Are SIM Cards waterproof?
Typically, a SIM card is only a chip and there is literally no space where water can get into and damage the components. Although prolonged exposure to water can cause rust or other damages, a momentary spill is nothing to worry about.
Who manufactures the most SIM Cards?
A French-Dutch digital security company by the name of Gemalto is credited with the most amount of SIMs manufactured. It is also currently the world’s biggest SIM card producer.
What does it cost to manufacture a SIM card?
We actually do not know the exact amount spent on creating one single SIM card. However, it is widely believed that while initially, it cost around a dollar to manufacture a SIM card, today, the prices have fallen as low as a few cents per chip. However, this doesn’t include the substantial cost of R&D, design, plastic used, packaging, printing, or shipping.
Who invented SIM Cards?
The very first SIM card was invented by a Munich-based smart card maker, Giesecke & Devrient GmbH, in 1991. It directly followed the development of SIM plugins that was invented in 1989. The invention came at an opportune time when Europe had just adopted the GSM (Global System for Mobile Networks) protocols. The invention allowed users to not only subscribe to their preferred network but also enabled them to call numbers on different numbers, thus igniting the mobile revolution.