eSIM 101: What is eSIM? A Brief History of eSIM. How Does It Differ from Traditional SIM Cards? Discover How eSIM is Gradually Outpacing Traditional SIMs.

eSIM is an embedded electronic SIM card that functions as a virtual digital card. It allows users to remotely activate cellular data from telecom operators anytime, anywhere, without the need for a physical SIM card. This tiny chip can be directly embedded into any electronic device, such as smartphones, tablets, smartwatches, or even smart cars.
eSIM is an emerging technology that was first proposed by Apple in 2011 and is now widely used in advanced countries like Japan, South Korea, and the United States.

Unlike traditional SIM cards, eSIM is essentially a data file that can be downloaded to a mobile device via the internet. Functionally, it is identical to a regular SIM card, enabling various electronic devices to connect to the internet, make and receive calls, and send text messages. Additionally, eSIM can store multiple configuration profiles, meaning that a single device can support multiple phone numbers (1–20) and seamlessly switch between different network providers. For more detailed information, you can refer to the Baidu Baike entry on eSIM cards.

SIM cards, commonly referred to simply as SIMs, are officially known as Subscriber Identity Modules. These cards have always been in the form of a card, which is why they’re called SIM cards. In reality, a SIM card is a chip card with an integrated CPU. The technical construction of the chip inside a SIM card is quite complex, but I won’t delve into it here. After all, this content is meant to be accessible and easy to understand, and getting too technical might make it hard to follow. However, don’t worry—I’ll provide a detailed explanation in a dedicated technical column, where I’ll cover the chip’s structure, principles, and related technologies comprehensively. If you’re interested, be sure to keep an eye out for it.

Before eSIMs came along, our phones all used traditional SIM cards. These cards have been around for decades, evolving from the original standard-sized card (Standard SIM) to the smaller Mini SIM, then to the Micro SIM, and finally to today’s Nano SIM. Although the size has decreased over time, they are still essentially plastic cards.

Traditional SIM cards have been incredibly useful, allowing us to make calls, send texts, and access the internet. However, they do have some drawbacks. For example, every time you switch phones, you have to carefully remove the SIM card and insert it into the new device, risking the chance of losing it. Additionally, the SIM card slot takes up space inside the phone, complicating the device’s design.

While traditional SIM cards were still comfortably holding their ground, eSIM emerged quietly as a "new star" on the scene.

• 2011: Apple filed the first patent for a virtual SIM card. This can be seen as the "embryonic stage" of eSIM. At that time, few people realized how powerful this little innovation would become in the future.
• 2014: Apple embedded Apple SIM into the iPad Air 2 and iPad Mini 3, allowing devices to dynamically choose carrier networks. It was like giving devices "wings" to switch between different networks freely.
• 2016: The GSMA (Global System for Mobile Communications Association) released the eSIM specifications for smartphones, which was supported by numerous global carriers and device manufacturers. This effectively rolled out the "red carpet" for eSIM, bringing it to center stage.
• 2017: Samsung's Gear S2 smartwatch and Apple's Apple Watch 3 began adopting eSIM solutions. This marked that eSIM was not only suitable for smartphones but also capable of shining in various smart devices.
• 2018: Google's Pixel 3 series of phones joined the eSIM camp. This further demonstrated the "charm" of eSIM, prompting more and more device manufacturers to pay attention to it.

Since then, eSIM has taken the tech world by storm like a rising star. An increasing number of smartphones, smartwatches, tablets, and other devices have started to support eSIM functionality. Today, eSIM has been widely adopted globally and has become an important way of connecting to the network.

Before diving into this topic, I'd like to clear up a common misconception about SIM cards. Traditionally, people have referred to mobile phone cards collectively as SIM cards, but this isn't entirely accurate. The SIM card, based on GSM (Global System for Mobile Communications) technology, is a Subscriber Identity Module that stores users' identity information and encryption keys for user authentication and communication encryption on GSM networks.

However, things are different for CDMA (Code Division Multiple Access) technology, which was the main competitor to GSM. Early CDMA phones didn't use SIM cards at all. Instead, they identified users and assigned phone numbers through other means. Specifically, CDMA phones could obtain phone numbers in two ways:

1. Pre-programmed into the phone: Carriers would write the phone number directly into the phone at the time of manufacturing and then sell the phone to users.
2. Over-the-Air (OTA) activation: Using OTA technology, users could send a specific message in a designated format upon first turning on the phone to write the phone number information into the device.

This card-less design was common among international CDMA carriers, and many of their phones still use this method today. However, the situation in China is unique. When China joined the WTO, it established a CDMA network as part of its negotiations with the U.S. But China made a "small modification" to the CDMA network, requiring phones to have a card slot. As a result, CDMA phones in China use a UIM card (User Identity Module), which is the user identification card for CDMA networks.

This difference mainly stems from the distinct design philosophies and implementation methods of GSM and CDMA technologies. GSM uses time-division multiple access and relies on SIM cards for user identification and management. In contrast, CDMA, which uses code-division multiple access, initially identified users through pre-programming or OTA activation.

Traditional SIM cards are physical plastic cards with a defined shape and size. Even though Nano SIM cards are quite small, they still come with several issues:

• Space Occupation:
• Limited Device Space: The SIM card itself, along with the card slot structure and wiring, takes up valuable space inside the device. For wearable smart devices such as smartwatches, fitness bands, and smart glasses, where space is extremely limited, even a Nano SIM card is too large.
• Cost of Communication Functionality: The space sacrificed for communication functionality is unreasonable for devices that aim to be compact and lightweight.
• Water Resistance:
• Slot Gaps: The gaps in the SIM card slot can significantly compromise the water resistance of the device, which is a major drawback for devices intended to be used in various environments.
• Connection Reliability:
• Non-soldered Contacts: Traditional SIM cards rely on metal contacts inserted into the slot, which can easily lead to poor connections.
• Challenges for Wearables: Wearable devices are often subject to bumps and impacts, which can cause the SIM card to loosen or fall out over time, affecting the device's normal operation.
• Difficulty in Changing Numbers:
• Traditional SIM Limitations: The process of changing numbers with traditional SIM cards is cumbersome and inconvenient, especially when users need to switch numbers or devices frequently.

In contrast, eSIM technology completely revolutionizes the concept of traditional SIM cards and addresses many of these pain points:

• Embedded Design: eSIM is directly integrated into the device's chip, eliminating the physical card altogether. It transforms from a "tangible" card to an "intangible" chip embedded within the device.
• Space-saving: Without the need for a card slot or wiring, eSIM significantly reduces the internal space requirements of the device, making it ideal for compact wearable devices.
• Enhanced Water Resistance: The absence of a card slot means fewer gaps, significantly improving the device's water resistance.
• Stable Connectivity: The embedded design eliminates the risk of poor connections, enhancing the device's reliability and durability.
• Convenient Number Switching: Users can easily switch numbers through software operations without needing to replace physical cards, greatly enhancing the user experience.

Traditional SIM cards require a card slot to function. Every time you switch phones, you have to go through the hassle of removing and inserting the card, which can easily lead to losing it. Moreover, the SIM card slot takes up valuable space inside the device and complicates its design. In contrast, eSIM eliminates the need for a card slot altogether. It is embedded directly into the device, making it incredibly convenient to use. You can easily activate and manage eSIM through your phone settings or a related app, and switch networks anytime, anywhere.

Traditional SIM cards have relatively limited functionality, primarily serving the following basic communication services:

• Making phone calls
• Sending text messages
• Accessing the internet

While these functions meet basic communication needs, they fall short in terms of flexibility and convenience. On the other hand, eSIM not only retains all the functions of traditional SIM cards but also offers several advanced features and advantages:

• Multi-carrier Switching:
  
• Traveling Abroad: When traveling overseas, users can quickly switch to a local carrier network via eSIM, enjoying more favorable rates without the need to go through cumbersome procedures at a carrier store.
• Multi-SIM Support: Users can flexibly switch between different carriers on the same device, catering to diverse communication needs.
• Remote Configuration and Programmability:
  
• OTA (Over-The-Air): eSIM supports remote configuration through OTA technology, allowing users to download, install, activate, deactivate, and delete carrier profiles.
• Flexibility and Convenience: Users can update and manage their SIM card information through simple software operations, anytime and anywhere, without the need to physically replace the card.
• Device Compatibility and Expandability:
  
• Multi-device Support: eSIM is not only suitable for smartphones but is also widely used in wearable devices, IoT devices, and more, providing stronger communication support for smart devices.
• Future Expansion: As technology advances, eSIM can support more innovative functions, such as remote management of IoT devices and seamless connectivity for intelligent transportation systems.

Traditional SIM cards have been shrinking over time, but they still have a physical form that occupies space. In contrast, eSIMs are embedded directly into the device's chip, taking up virtually no space. This allows device manufacturers to design more freely, making products like smartphones and smartwatches thinner and lighter. For example, some ultra-thin smartwatches simply couldn't accommodate a traditional SIM card without eSIM technology, and thus wouldn't be able to offer independent network connectivity.

Traditional SIM cards require a physical slot for insertion and removal. Every time you switch devices, you have to go through the hassle of removing and inserting the card, which can easily lead to losing it. Moreover, SIM card slots are prone to dust and water ingress, compromising the device's water resistance. In contrast, eSIMs eliminate these issues. With no physical card, you can activate and manage eSIMs through your device settings or a dedicated app, and switch networks anytime, anywhere. For example, when traveling abroad, you can simply switch to a local carrier network on your phone, enjoying more favorable rates without the need to visit a carrier store for complicated procedures.

Traditional SIM cards are relatively limited in function, primarily used for making calls, sending texts, and accessing the internet. In contrast, eSIMs not only retain all these functions but also offer advanced features such as multi-carrier switching and remote configuration. For example, you can install multiple eSIMs on your phone and switch between networks based on different scenarios and needs. This is incredibly convenient for frequent travelers who need to use multiple carrier networks.

Traditional SIM cards, being physical objects, are susceptible to copying, tampering, or theft. In contrast, eSIMs are embedded in the device's chip, with data stored in a secure element, significantly enhancing security. It's like adding a "lock" to your network identity, making it much harder for others to steal your information.

The production, packaging, and transportation of traditional SIM cards add to costs and environmental impact. In contrast, eSIM technology offers significant advantages in terms of cost and environmental sustainability:

• Lower Costs: eSIMs eliminate the need for separate production, packaging, and transportation, reducing logistics costs and material consumption.
• Greener Design: Since eSIMs are embedded in the device's chip, they avoid the industrial waste generated during the production of traditional SIM cards, reducing environmental impact.
• Benefits for All: For carriers and device manufacturers, eSIMs lower operational costs and improve production efficiency. For consumers, a more sustainable production process means more affordable prices and more sustainable product choices.

With this overview, we have a clear understanding of the evolution of eSIMs. In fact, beyond eSIMs, there are even more advanced forms like softSIM and vSIM, which can be seen as the ultimate direction for SIM technology. However, these topics will not be covered in detail here.

Precisely because eSIMs offer so many significant advantages, major telecom operators worldwide are eagerly embracing eSIM technology. With the rapid development of the Internet of Things (IoT), the future will be a world of interconnected devices. Driven by IoT technology, the adoption of eSIMs will undoubtedly accelerate. It is believed that in the near future, traditional "SIM cards" will gradually fade from our lives.