Here’s a complete overview of what eSIM is, how it works, and why it is replacing the traditional SIM card…


An eSIM is an embedded-SIM that is built directly into a phone. There’s no slot, just an updateable SIM card that lives internally inside your phone. Unlike physical SIM cards, eSIMs reduce plastic waste and can’t be lost or stolen.

They also enable a phone to have a new number assigned without requiring the purchase of another physical SIM card, making international travel much easier.

  • An eSIM is already built into your phone, eliminating the need for a physical SIM card.
  • eSIMs reduce plastic waste and can’t be lost or stolen.
  • A new number can be assigned to an eSIM without requiring another physical SIM card.
  • International travel is made easier with an eSIM; users can simply use a local carrier’s app to get a temporary phone and data plan for the country they are in.
  • The adoption of eSIMs is growing rapidly as they offer many advantages over traditional physical SIM cards.

For almost as long as there have been mobile phones, including iPhones, there have been SIM cards. SIM cards are those tiny pieces of plastic with a golden chip printed on them that we insert into our smartphones.

iPhones run SIM Cards and so too do Android phones. Even old school brick phones like the Nokia 3310 ran SIM Cards. To connect to a network, you need a SIM.

And your SIM will have a unique ICCID and IMSI number that relates to its country of origin and the networks it is authorised to connect to.

But recently the age-old, humble SIM card is being usurped by a new variant–the eSIM. Here’s what you need to know.

What Is A SIM Card?


A SIM card is that tiny plastic card with a golden chip printed on it. SIM stands for subscriber identification module and the cards have been around since the early 1990s.

However, with the mass adoption of smartphones in the mid-2000s their use exploded. Today, SIM cards are a necessary component of any smartphone–at least if you want cellular and data access via the phone.

Depending on how old a phone is, it could require a different0sized SIM. Matter of fact, there are currently four physical types of SIM cards. They are:

  • A full-size SIM: this is the earliest SIM from the 1990s and was a massive 3.3 x 2.1 inches. It’s safe to say no modern phone–or any phone made in the 21st century uses this type of SIM anymore.
  • Mini-SIM: this is the next iteration. Mobile phones between 1996 and 2003 used this type of SIM. No smartphone is known to have supported this type of SIM. It was 0.9 x 0.5 inches.
  • Micro-SIM: Introduced in 2003, this is the first SIM card many of us were probably aquatinted with. It’s the last SIM with a noticeable plastic border around the golden chip printed on it. It was 0.5 x 0.4 inches. Some smartphones today may still use this type of SIM, but it is becoming rare.
  • Nano-SIM: this is the type of SIM card virtually every smartphone supports now. It’s only 0.4 x 0.3 inches, which is barely enough to hold the golden chip printed on it, hence the nano-SIM doesn’t have a plastic border.

What Info Does A SIM Card Contain?

SIMs contain information like your phone number, other unique identification numbers like ICCIDs and IMSIs as well as IANs and EANs. These numbers all help identify your SIM and link your cellular data plan to that SIM card, thus enabling internet access on the smartphone your SIM card is in as well as cellular and text services.

SIM cards also carry a limited amount of storage capacity. The max is 256kb–not much at all. But because of this capacity, SIMs can contain things like your phone contacts, although today those are more likely to be saved in a user’s cloud account.

Finally, a SIM also contains a PIN number, which lets you lock it and helps prevent anyone from gaining access to your phone number and service should they steal your SIM. Finally, a SIM contains a PUK number, or personal unblocking key. This is a security measure that prevents unwanted SIM access.

How Is An eSIM Different?

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An eSIM is different than a SIM because there is no physical SIM card the user obtains that they need to insert into their smartphone. eSIM stands for embedded-SIM, which means it’s already built into the phone you bought.

eSIMs are the new frontier and the future of SIM tech for several reasons:

  • They reduce plastic waste by not being a physical card.
  • They can’t be lost or stolen.
  • They mean a phone can have a new number assigned to it without the need to buy another physical SIM card.

This last point is a big deal because it makes international traveling much easier. Now when you land in a new country, you no longer need to rush to the airport kiosk to swap out your SIM with a local SIM.

Instead, you could just use a local carrier’s app to get a temporary phone and data plan for the country you are in. Pretty cool.

And in 2023, a new generation of SIM card was launched – iSIM. You can read all about how iSIM works here.

Are eSIMs Better Than SIMs?

Yes. The fact that they do away with any kind of physical card makes them both easier to manage and more secure.

What Phones Have eSIMs?

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Many phones have eSIMs nowadays. Matter of fact, many flagship smartphones have both a regular SIM slot and an eSIM built-in, making them dual-SIM phones. This allows one phone to have two different phone numbers.

Apple iPhones that offer eSIM support include:

  • iPhone XS
  • iPhone XS Max
  • iPhone XR
  • iPhone 11
  • iPhone 11 Pro
  • iPhone 11 Pro Max
  • iPhone 12 Mini
  • iPhone 12
  • iPhone 12 Pro
  • iPhone 12 Pro Max
  • iPhone SE (2020)
  • iPhone 13 series
  • iPhone 14 series
  • iPhone 15 series

Android phones that have eSIM support include:

  • Huawei P40, P40 Pro
  • Google Pixel 3A or 3A XL
  • Google Pixel 4 or 4XL
  • Google Pixel 5
  • Motorola Razr 2019
  • Samsung Galaxy S20, S20+, S20 Ultra
  • Samsung Galaxy Z Flip
  • Samsung Galaxy Fold

And check out Which iPhones Have eSIM?