Imagine a phone without internet access, without the ability to send messages or make calls. Sounds like drifting without a network on the open sea? It's the SIM card that makes a phone function properly. In the article below, we explain the types of SIM cards in modern devices and what functions they perform in the GSM system.
Key takeaways from the article:
- A SIM card is a digital user passport – it identifies the subscriber in the operator's network, stores data, contacts, and enables the use of GSM services.
- SIM card types have changed with technological development – from large credit card-sized cards, through mini SIM, micro SIM and nano SIM, to the embedded eSIM.
- Miniaturization was crucial – successive generations of cards became smaller and thinner, allowing for the design of slimmer and more advanced devices.
- eSIM is the future – it doesn't require physical installation, allows remote operator changes, supports multiple profiles, and increases security in case of phone theft.
- SIMs differ not only in size but also in functionality – newer cards (USIM, nano SIM, eSIM) offer larger memory capacity, faster service activation, and better security.
What is a SIM card?
The acronym SIM (Subscriber Identity Module) stands for Subscriber Identity Module. In short, a SIM card is a type of smart card that acts like a passport or ID card, uniquely identifying a mobile phone user in the operator's network.
The SIM card itself consists of an integrated circuit and a plastic casing. The built-in microprocessor and memory allow for storing subscriber identification data, such as the unique IMSI (International Mobile Subscriber Identity) and ICCID (Integrated Circuit Card Identifier) numbers. The IMSI number identifies the subscriber in the operator's network, enabling authentication and access to telecommunication services.
You'll find more info on our board in the article: What is a SIM card?
What does a SIM card contain and what information does it store?
A SIM card not only stores subscriber identification data but also allows for saving contacts and some SMS messages. This makes it an integral part of the GSM system and a fundamental element for using mobile operator services. The operator manages the SIM card, and ETSI standards define the format and functions of the cards, ensuring their compatibility with various phone models and mobile devices.
What can you find out from a SIM card?
- Which operator issued the SIM card.
- What the subscriber's phone number is.
- Who owns the card.
Types of SIM cards – from credit card-sized to millimeter solutions
Technologies are developing incredibly fast. The world strives to create the biggest, fastest, and most effective things. SIMs took a different course – they got smaller every year, eventually almost disappearing from view. This allowed for user convenience and compatibility with increasingly compact devices.
It's no coincidence that the first mobile phones were so large. SIM card dimensions in the 90s were as large as 85 mm x 54 mm! They enabled sending text messages and making calls.
A fun fact from the voyage: some premium cars (e.g., BMW) had phones installed with slots for such SIMs.
What network technologies do different types of SIM cards support?
Different types of SIM cards can support various network technologies, such as 2G, 3G, 4G, and even 5G. As mobile networks developed, SIM cards also evolved – from basic SIM versions to enhanced USIMs, which are adapted for newer standards. USIM is an improved version of the SIM card, dedicated to 3G networks and newer, offering larger memory capacity and better security.
Standard SIM card (Mini SIM)
Introduced to the market in 1996. The standard SIM card, often called miniSIM, measures 25 mm x 15 mm. This size made phones significantly lighter and more portable. They were used for about 10 years, during the era when the first phones with color screens and cameras emerged.
MicroSIM
Introduced in 2003, microSIMs took 7 years to become standard. The launch of the iPhone 4, which caused a sort of "boom" for these types of cards, helped them achieve this. MicroSIM measures 15 mm x 12 mm, which means a significant reduction in the amount of plastic around the microprocessor chip. This allowed these cards to fit better into increasingly thinner and smaller devices.
NanoSIM
The nanoSIM format debuted in 2012. These cards almost entirely eliminated plastic – they were reduced practically to the size of the microprocessor itself. Nano SIM is 12.3 mm long and 8.8 mm wide, and its thickness was reduced from 0.76 mm to 0.67 mm. The first device to use this standard was the iPhone 5. NanoSIM not only takes up little space on board the phone but also activates services faster – meaning you set sail towards the internet more quickly.
What are the thickness differences between individual SIM card types?
In addition to reduced length and width, SIM cards also differ in thickness. The standard SIM card and microSIM are about 0.76 mm thick, while the nano SIM was slimmed down to 0.67 mm. This change, though small, allowed device manufacturers to further miniaturize and better utilize space inside phones.
What are the memory capacity differences between different types of SIM cards?
Different types of SIM cards also vary in memory capacity, which affects the amount of stored data, such as contacts or SMS messages. Newer cards, especially USIMs, offer greater capacity and better data management capabilities, which is important in the context of growing user needs and the development of mobile services.
eSIM – a card without dimensions
This is the latest solution available on the market, in Poland called an embedded SIM card. What is an eSIM? It's an embedded electronic module that is written directly onto a microchip in the device. This eliminates the need for physical SIM card replacement, significantly increasing user convenience.
eSIM enables remote management of the subscriber profile, meaning you can activate or change operators without needing to replace a physical card. Furthermore, eSIM supports multiple operator profiles on a single device, which is particularly useful in LTE-enabled tablets, IoT devices, or mobile phones supporting multiple numbers.
And if someone swipes your phone – a classic SIM can be removed in a second, while an eSIM remains anchored to the device's deck. This is an additional shield for a Viking.
What are the differences in installation methods between SIM card types?
Traditional SIM cards (mini, micro, nano) require physical insertion into a dedicated slot in the device. Each of these formats differs in size, which affects compatibility with specific phone models. eSIM, on the other hand, is built into the device and does not require physical installation. Configuration takes place digitally, which greatly simplifies managing operator services.
How do SIM card types affect the speed of network service activation?
More modern SIM cards, such as nano SIM and eSIM, offer faster network service activation thanks to streamlined data writing and reading processes. eSIM also enables instantaneous operator changes without the need for physical card replacement, which translates into greater flexibility and user convenience.
Compatibility and application of different types of SIM cards
SIM card types differ not only in size and installation method but also affect compatibility with mobile devices. The standard SIM card was commonly used in older phones. MicroSIM and nanoSIM dominate in modern smartphones, LTE-enabled tablets, and IoT devices. eSIM, on the other hand, is used in the latest phone models, smartwatches, and other devices requiring flexibility in managing subscriber profiles.
All types of SIM cards adhere to ETSI standards, which define their format and functions, ensuring interoperability and security of use. SIM cards can be single-use or reusable, and they allow for transferring phone numbers between different devices, which is a significant advantage for users.
What future awaits SIM cards?
Observing the trends and continuous miniaturization of SIM cards, we can expect that physical versions will soon simply disappear. eSIM cards are the first step in this direction. Perhaps soon we'll be reminiscing about plastic models during "boomer" moments of nostalgia. However, nothing indicates that the solution itself, which is a card (or in today's world, an e-card), will abandon us. It is and will continue to be one of the basic components of phones, tablets, and IoT devices, enabling authentication in the mobile network and access to operator services.
With technological development and increasing user demands, the evolution of SIM cards will move towards miniaturization, integration, and digitalization, enhancing the convenience and security of using mobile devices.
FAQ – Frequently Asked Questions
1. How does a microSIM card differ from a nanoSIM?
MicroSIM (15 x 12 mm) has more plastic around the chip. NanoSIM (12.3 x 8.8 mm) is thinner (0.67 mm) and virtually limited to the microprocessor itself. NanoSIM is like the "fit" version – less plastic, more power, and a faster start on the network.
2. How to check what type of SIM card I have?
The easiest way is to remove the card from the phone slot and measure or compare its size: miniSIM (25 x 15 mm), microSIM (15 x 12 mm), nanoSIM (12.3 x 8.8 mm). eSIM has no physical form – you can check it in your phone settings.
3. Can a microSIM card be made into a nanoSIM?
Yes, a microSIM can be cut to nanoSIM size – but this requires precision to avoid damaging the chip. Pro tip: instead of playing home boat builder with scissors, it's better to ask your operator for a replacement. Or, even better, jump straight to eSIM – no fuss, complete freedom.
