What Is an eSIM and How Does it Work

Oct 12, 2023

Embedded SIM cards (eSIM) are increasingly replacing physical SIM cards in smartphones and other devices. But what is a Europe eSIM, for example, and how does one work? This article looks at the basics of the eSIM and at why they offer a range of benefits over traditional plastic SIM cards.

First introduced in 1991, a traditional subscriber identity module (SIM) consists of a small plastic card with a silicon integrated circuit chip that is placed in an ejectable slot within a mobile phone. The SIM stores the user's "profile", with such data as contact lists, personal security keys, phone number and identity. A SIM card allows the user to use their device to send text messages, make phone calls, and connect to mobile internet services. The card is removable, so the user can take the SIM from one device and insert it into another and also switch mobile plans while keeping their existing device.

While it began life the size of a credit card, between 1996 and 2012 smaller SIMs were developed – the mini (or standard), the micro and the nano. The most common size is now the nano. The size was reduced by cutting down the plastic border around the chip. The latest development in SIM technology has been to get rid of the physical card altogether, in favor of the eSIM, which is a microchip embedded in the mobile phone. Not all phones are compatible with an eSIM at the present time. However, selected Samsung and Google devices and the Apple iPhone (the XS model onwards) offer eSIM functionality.

Unlike a physical SIM, an embedded SIM cannot be removed from the device but it is rewritable. This essentially means the user can change their network without having to remove the SIM and insert a different one. Multiple profiles can be stored on the eSIM without the need to switch SIM cards, so the user can activate different data plans and phone numbers. The number of profiles varies depending on the device, with iPhone users able to activate up to 20 and Samsung Galaxy devices allowing up to five profiles. When a user wants to add a profile, they can set up a virtual SIM by simply scanning the barcode or quick response (QR) code provided using the camera function on their device. There are various steps to configure the card, which depend on the type of device.

There are several benefits of an embedded SIM over a physical SIM. For example, the eSIM microchip is smaller than the nano SIM and no slot is required for a physical card. Phone makers are still currently including a physical slot alongside eSIM capabilities. However, eventually, the elimination of the plastic SIM will save space within the phone for additional components and features or a larger battery. Conversely, it can also contribute to makers producing smaller devices, which has particular benefits for smartwatches and other wearables. In addition, fewer physical SIM cards means less resources are needed and less waste is generated.

One of the main benefits for users is that an eSIM makes it easier to switch between networks or to have multiple phone numbers on the same device, such as a business number and a personal number. The practical benefits for users include not having to worry about losing or damaging a physical SIM. One drawback is that it is not as easy to switch devices while keeping the same SIM. However, currently, the eSIM works alongside a physical SIM, as with a dual SIM device.

An eSIM also makes staying connected while traveling simpler and more flexible. Users with a compatible device can purchase an overseas data plan as a virtual SIM and scan the code provided to unlock the data. This way, they can avoid high roaming charges imposed by mobile networks for using their device outside the home area. This is also a good solution for travelers who plan to visit more than one country. Rather than having to insert a different card for each country, users can, for example, purchase a Europe eSIM to enjoy their data plan throughout the region, as well as make calls using WhatsApp or Skype.

Overall, while it might be some time before the eSIM completely replaces the plastic SIM, the technology is gaining traction, as the leading phone manufacturers look for ways to improve and streamline the user experience.