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What is eSIM – Embedded SIM Supporting Devices, SIM Vs eSIM, its Parts

eSIM refers to “Embedded Subscriber Identity Module” also called as Embedded SIM. This post will discuss what is eSIM, evolution of Embedded SIM, characteristics, how it is different from SIM, supporting devices, architecture, advantages & disadvantages.

What is eSIM

Before we talk about what an eSIM is, it is important to understand what a SIM is. SIM stands for “Subscriber Identity Module”. It basically contains the information that validates your identity to a carrier (Service Provider).

In other words, SIM card is all about telling a carrier that you are you and without it, a carrier wouldn’t know that you’re subscribed to their network, and thus would not let you use their cell towers. The SIM card has survived for a quite long but it now finally looks like it’s on its way out. eSIM is a much smarter technology.


Fig. 1 – Introduction to eSIM

The term “eSIM” stands for “embedded SIM”. eSIM is digital SIM that is used to authorize user to activate a cellular plan from a carrier without using any physical SIM card. eSIM needs to be supported by the carrier or network and enabled by them and not all networks support eSIM as yet.

eSIM refers to a small chip embedded inside your device that works like a NFC chip (Near-Field Communication Chip) which is used for payment technology like Apple Pay and Google Pay. eSIM is rewritable that means information on eSIM’s is rewritable and you can change your operator with a simple phone call.

sim vs esim

Fig. 2 – SIM vs eSIM

Schematic representation of SIM and eSIM is shown in Fig. 2 above. Profile consists of the operator data related to subscription details. eUICC is the secure element in eSIM and it can accommodate multiple Profiles. Profiles are remotely downloaded using over-the-air management into a eUICC. The structure and the content of the profiles stored on eUICC is similar to traditional SIMs.

Evolution of SIM

  • From full size SIM cards to Nano SIM cards, size of SIM cards was reduced drastically over the past 25 years.
  • Next revolutionary step is the introduction of the Embedded SIM (eSIM).
  • It saves 90% space compared to Nano SIM card (including the SIM slot and contacts).


Fig. 3 – Evolution of SIM

Characteristics of eSIM

The characteristics include:

  • It is a non- removable SIM.
  • Hardware is integrated in the device.
  • The user data is stored in the profile.
  • SIM profile is transferred wirelessly (over the air) to the device.
  • It provides easier switch between operators.
  • Improvement in customer experience.

Devices that Support eSIM

It is mostly introduced in Apple gadgets and is available in latest Apple phones and tablets.

  • eSIM is available in iPad Pro, Apple Watch Series 3, 4 and 5 and dual SIM support is available in iPhone XS, XS Max, XR as well as in iPhone 11 and 12 series.
  • Google’s Pixel 2, Pixel 3 XL and Pixel 4, Pixel 4 XL, Pixel 4a also supports embedded SIM.
  • It is also available in Galaxy S20, S20+ and S20 Ultra.

Note: There are many more makes and models that support e-SIM. The list above here represents only popular and widely used models.

eSIM vs SIM Card

Sim Vs EsimArchitecture of SIM

SIM card which is a smart card with a microprocessor consists of the following components:

  • Central Processing Unit (CPU)
  • Random Access Memory (RAM) (Working memory)
  • Read-Only Memory (ROM) (Program memory)
  • Electrically Erasable Programmable Read-Only Memory (EEPROM)
  • Serial communication module

The operating system is stored on the ROM and data and applications are stored on the EEPROM.

Embedded SIM Architecture provides a more flexible and reliable environment for handling applications on the SIM. Downloading of applications is handled by Over-the-Air (OTA) management which helps in interoperability across card manufactures for loading of Java-based applets onto the SIM card from any source.

Embedded SIM Architecture

Fig. 4 – Embedded SIM Architecture

Advantages of Embedded SIM

The advantages are:

  • Device setup is much simple as inserting or replacing a SIM card is not needed.
  • Carriers can be changed without having to get a new SIM. This means less time taking with carriers and ordering and waiting for new SIMs. Software does everything.
  • No need to deal with cutting SIM cards.
  • No more looking for an ejector tool or a paperclip to change the eSIM.
  • SIM card and eSIM can be used in parallel on the same device at the same time, one number from physical SIM card and the other number from an embedded SIM can work.
  • Automatically new device can be configured to the previous number by registering it in your mobile account. For example, user can use same number on the phone and smart watch.

Single Profile and Multiprofile Swapping

Fig. 5 – Single Profile and Multi Profile Swapping

Disadvantages of Embedded SIM

The disadvantage include:

  • Biggest disadvantage of using embedded SIM in phones is that, whenever you change handsets you have to deal with letting your carrier know. In case of regular SIM card, you just insert it into the new phone. No discussion or interaction with the carrier is needed in case of regular SIM card.


We have seen the evolution of SIM cards from traditional hardware to IoT devices. Smart SIM cards now provide a new form of digitalization and easy access to connectivity and are considered a better option. Switching telecom providers is much easy for everyone due to embedded SIM (eSIM). Smart or Digital SIM  is going to be a game changer.

Also Read:
What is Smart card - How it Works, Specifications, Types and Applications
Cell Phone Sniffer Tracking System – How to Find Lost Phone & Block IMEI
Batteries of Future – Long Life, Full Charge in Seconds For Mobile Phone
Neetika Jain
Neetika Jain
Neetika is a B.Tech. (Computer Science) graduate and has 4 years of work experience in Infopro India Pvt. Ltd. as Software Tester. She is an author, editor and partner at Electricalfundablog.


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