SIM cards were once essential in an era when multiple users often shared a single mobile device, and the cards themselves were much larger. Today, SIMs have shrunk dramatically and, in many ways, are no longer necessary due to the emergence of eSIM technology.

eSIMs—embedded, virtual SIM cards—were designed to simplify mobile connectivity, making it as effortless as connecting to Wi-Fi while eliminating the inconveniences tied to physical SIM cards. However, while the technology set out to resolve longstanding issues, it has introduced a new set of challenges in the process.

One of the biggest advantages promised by eSIMs was seamless network switching without the need for physical cards. Traditionally, travelers had to purchase local SIM cards abroad to avoid high roaming charges, often swapping out their primary SIM and storing it safely. eSIMs improve this experience significantly, allowing users to activate international plans digitally through services like Saily.

Despite this convenience, the level of ease still largely depends on individual carriers. In many cases, users must navigate complex activation steps, and switching between networks isn’t always as smooth as expected. Additionally, carrier-locked devices can prevent eSIMs from functioning across different networks, limiting flexibility.

Transferring a mobile number between devices has also become more complicated with eSIMs. With a physical SIM, users can simply move the card from one phone to another. In contrast, eSIM transfers often involve multiple steps and may even require contacting customer support—especially if the original device is lost or damaged.

While these additional steps are partly necessary to prevent fraud, such as unauthorized SIM swaps, they can still be inconvenient. For users who frequently change devices, this added friction can be a significant drawback.

Although the concept behind eSIM technology is strong, the current ecosystem is not fully prepared to deliver a seamless digital experience. A standardized process for activation and transfer across devices and carriers is still lacking. Ideally, users should be able to move eSIM profiles easily between devices, regardless of brand—whether switching from iPhone to Android or vice versa.

Moreover, many restrictions carried over from physical SIM systems still exist in the eSIM space, and these need to be reconsidered. Switching between multiple eSIMs on the same device also requires further refinement.

Ultimately, the goal should be to move beyond simply digitizing the traditional SIM model. A more advanced system could allow users to connect to available carriers instantly using login credentials, similar to accessing public Wi-Fi. With emerging technologies like passkeys, the reliance on SIM cards and phone numbers for authentication may soon become outdated, paving the way for a more streamlined and user-friendly mobile connectivity experience.