What are the differences between an eSIM and a physical SIM card?

Nowadays, most mobile network operators offer their plans via a physical SIM card or a digital version, also called an eSIM. How do these two technologies work? What makes them different? Which one is more convenient for everyday use or while traveling? Our experts answer all your questions.

SIM card and eSIM: how do they work?

Before diving into the differences between an eSIM and a SIM card, it’s important to understand the role of this essential component in mobile telephony.

What is a SIM used for?

A SIM card is a smart card used in telecommunications to store information related to a mobile network user. It contains a microcontroller and storage space that allows it to store all the connection details of a subscriber, network settings, and even data like a contact list. It is inserted into a dedicated slot in a phone and can be easily removed and transferred to another device.

The acronym SIM stands for Subscriber Identity Module. A SIM card allows a network’s antennas to verify a subscriber’s identity using a unique identifier, called IMSI (International Mobile Subscriber Identity). In short, it’s the component that allows a user to connect to their mobile network and communicate via their phone!

The SIM card has evolved to meet the changing needs of the telecom market. It comes in several formats:

● Standard SIM: The original 1991 version, which measured 2.5 x 1.5 cm! This format was quickly replaced by a more compact version.

● Mini SIM: the format used from the mid-1990s to the mid-2010s.

● Micro SIM: Introduced in 2003, this 1.5 x 1.2 cm SIM was the standard during the 2000s and 2010s, coinciding with the rise of smartphones.

● Nano SIM: The most recent version of the physical SIM, this ultra-small 1.2 x 0.8 cm SIM is the most widely used format today.

How does an eSIM work?

In 2016, a new version of the SIM card appeared: the famous eSIM! This digital SIM card is embedded directly into the hardware of modern smartphones. eSIM is short for embedded SIM! It’s a universal SIM card that can be configured with the connection details of any subscriber and operator, enabling connection to any mobile network.

The way an eSIM works is similar to a traditional SIM card, except that connection details are not stored in a chip, but are downloaded and installed directly onto the smartphone's embedded SIM. These details are referred to as a “eSIM profile”, which needs to be downloaded onto a device to activate a network. When switching devices, instead of transferring a SIM card, you download a new eSIM profile. You can also store multiple eSIM profiles on a single device (up to 5).

Which devices are compatible with eSIM?

Most smartphones released after 2020 are compatible with eSIM. This technology is also found in other connected devices like computers, tablets, and smartwatches. It’s even used in some cars to provide onboard Wi-Fi!

Note that, aside from a few models, eSIM-compatible smartphones also feature a physical SIM slot, allowing users to choose between both options.

Can you use an eSIM and a physical SIM at the same time?

Just like dual SIM phones allow two phone lines, it's possible to use both a SIM card and an eSIM simultaneously on compatible devices. You can also use one number for voice/SMS and another for data, which is especially useful when traveling.

Do all carriers offer SIMs and eSIMs?

The physical SIM card was long the only option for carriers to deliver their services. But the rise of eSIM technology and its adoption in modern smartphones has changed everything. Today, most carriers offer both options, giving customers the ability to choose between SIM and eSIM. So it’s important to understand their pros and cons to make the right decision.

Physical SIM vs. eSIM: Pros and Cons

Both the SIM card and the eSIM have their strengths and weaknesses, which can impact their daily use.

Pros and cons of a traditional SIM card

Still the most widely used format today, the physical SIM card has the advantage of being compatible with all phones on the market, old and new.

It can also be easily moved from one device to another, even when formats differ. Physical SIMs are available in multi-cut versions (mini, micro, nano), making transfers simple in case of device changes or failure.

However, this flexibility comes at a cost, including an environmental cost. Producing SIM cards requires plastic and conductive metals, which are non-renewable. Additionally, SIMs must be physically delivered to the user, resulting in shipping costs, CO₂ emissions, and several days’ delay before the plan is usable.

Pros and cons of an eSIM

As a digital solution, the eSIM requires no manufacturing or shipping. This not only reduces environmental impact but also allows instant delivery of plans! Once you subscribe to a plan, you receive an eSIM profile to install on your phone: your line is activated immediately, sometimes in seconds. This is the eSIM’s biggest advantage!

It’s also ideal for people who need multiple lines on one phone—for business, travel, or accessing services in different countries. This benefits cross-border users and tourists who want to stay connected without hassle. That’s why many operators now offer international travel eSIMs, like UPeSIM.

How to choose between SIM and eSIM?

Still undecided between a physical SIM and a digital eSIM? Here are some tips to help you choose.

Why stick with a physical SIM instead of an eSIM?

Even though eSIMs offer many benefits, some people may still prefer traditional SIMs. Those uncomfortable with technology or who don’t use smartphones might opt for a standard SIM, which still meets most basic needs. Sometimes, going offline is a good thing too!

Why choose an eSIM over a SIM card for daily use?

For everyday use, the eSIM is the best choice for smartphone users who want to switch plans easily. With instant activation, you can subscribe to a new plan and change providers as often as you like.

It’s also the best solution for users who need multiple plans. While you can’t have more than two numbers active at once, you can have various data plans for different needs, like internet or travel use.

Why is eSIM the best option for travel?

Many operators now specialize in travel eSIMs because they are the ideal solution for staying connected abroad! Instead of buying a local SIM at the airport, you can subscribe to an international eSIM plan the day before or the day of departure, for instant connection upon arrival. Enjoy mobile data without roaming fees and keep your regular number to stay reachable. You can use all your regular apps, including WhatsApp for calls and texts.

At UPeSIM, we offer all the benefits of eSIMs with 7, 10, or 30-day plans tailored to any trip. Get ready for your next holiday by choosing your eSIM plan among our 200 destinations!