A soft SIM, also referred to as a "virtual SIM," is a software-based Subscriber Identity Module (SIM) that eliminates the need for using SIM hardware. It is usually represented not by a physical SIM, but rather stored in the device memory and processor or modem.
Since a soft SIM is a software-based solution without a physical module, it doesn't look like a traditional SIM card or eSIM. The soft SIM exists purely as a collection of software applications and data stored within the memory and processor of a communication device. Its form relies on the user interface or software interface through which it is accessed and managed. This can vary depending on the specific implementation and the software platform used to handle the soft SIM functionality.
The reduction in SIM size offers advantages such as the ability to install smaller IoT sensors in versatile locations, empowering manufacturers and customers to select optimal positions for maximum protection and efficiency. Eliminating the need for a physical slot or space within the device makes it possible to provide more lightweight design and experiment with smaller device sizes.
The widespread adoption of soft SIMs has the potential to lower manufacturing costs and decrease production time as they eliminate the need to purchase and install physical components. Rather than acquiring fragile hardware that embeds software, the concept is akin to acquiring licenses for the software itself.
Similar to eSIMs, soft SIMs eliminate the requirement for a SIM card slot, eliminating the need for physical insertion or removal. By employing soft SIMs and eliminating SIM card slots, the risk of damage caused by dust, water, electric shock, vibration, or extreme temperatures is significantly reduced.
There is no governing body that establishes a standardized architecture for soft SIMs. This grants vendors significant flexibility in determining the implementation of a software-only SIM. However, manufacturers must evaluate the specifics, such as the storage location of the software, and assess how it impacts performance and reliability.
Although the notion of eliminating hardware may appear attractive, it is crucial to recognize that the absence of a physical component is not the sole consideration with soft SIMs. Placing the SIM on a modem or within the device's operating system can potentially introduce new vulnerabilities. Operators express significant concerns regarding the security of their credentials and the potential decrease in security associated with the usage of soft SIMs. Operating systems are commonly targeted by hacking attempts, posing a risk of compromising the operator profile to hacking activities.
The term ‘eSIM’ is often confusing as it refers to two distinct technologies: an MFF2 form factor and sometimes mistakenly as a synonym for embedded Universal Integrated Circuit Card (eUICC). Indeed, eUICC is a technology that implies management, adding and removing operators' profiles remotely without a dependency on the SIM format, while eSIM refers to the above-mentioned particular form factor. Anyway, neither of these technologies is synonymous with a soft SIM. Every eSIM has a dedicated hardware component. Even if the hardware is embedded, it still occupies physical space within the device. The same applies to the newer iSIM technology. On the other hand, a soft SIM consists solely of software and data, devoid of any physical module. Moreover, for SIM card manufacturers and vendors to label their product as an eSIM, they must adhere to the GSMA's standards for eSIM architecture. Notably, there are separate architectures for consumer eSIMs and M2M (Machine-to-Machine) eSIMs. Conversely, there is no regulatory institution or standard defining what constitutes a soft SIM.
