eSIM – what is it and how it works

Did you know your phone probably doesn’t need a SIM card? An eSIM can save you money and help you avoid dreaded roaming charges. We’ll explain what eSIMs are and why they’re so handy for travel.

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What is an eSIM?

An eSIM stands for embedded SIM (subscriber identity module). It’s a digital version of a traditional SIM card that does everything a physical SIM card would do — but uses a built-in eSIM chip on your device instead. eSIMs are available on smartphones, tablets, smartwatches, and even some cars!

They’re great for using several network operators and up to two phone numbers at the same time — and an excellent short-term solution for travel.

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How does an eSIM work?

An eSIM uses a built-in chip and preinstalled software on your device to do what a traditional SIM would — connect you to a network, enable calls, and provide mobile data.

To start using an eSIM, you’ll need to buy a data plan online and activate it on your device. You can skip the hassle of swapping out a SIM card — eSIMs are programmed remotely.

How to set up an eSIM

Before buying an eSIM plan, . Then, follow these steps to get an eSIM plan with Saily.


Choose a data plan for your trip

Select your destination and pick your data plan.


Download the app and set up your eSIM

Follow the steps in the app to set up the eSIM on your device.


Activate your plan before the trip

Remember to do this before you take off — you’ll need an internet connection.

Why use an eSIM?

eSIMs are great for many reasons.

Lower roaming charges

An eSIM lets you connect to a local carrier and avoid high roaming fees.

Pay for what you need

Off to Japan for a week? Get a 7-day plan instead of monthly, and save your yen for an extra okonomiyaki.

Less space

If a device doesn’t require a physical SIM card slot, it can be made smaller.

Stay safe online

With an eSIM, you can avoid some cybersecurity risks related to unauthorized SIM card use.

Multiple profiles

An eSIM lets you have several profiles — or “virtual” SIM cards — on one device. You can switch between carriers without swapping physical SIM cards.

Less waste

SIM cards are small but, at the end of the day, it’s still plastic waste that could’ve been avoided.

What is the difference between an eSIM and a physical SIM?

The main difference between physical SIM cards and eSIMs is that you can install and activate an eSIM yourself and it will support multiple network profiles.



Phone numbers

Up to two (currently, Saily eSIMs don't support phone numbers)

Up to two (if your device supports it)

Network Operators


Up to two (if your device supports it)


Deactivate the profile

Remove the SIM card


Remote: set it up on your device yourself

Manual: buy a card from a carrier and insert it


Newer devices

All old and most new devices

Using internationally

Affordable — easy to get data plans in different countries

Deal with expensive roaming or buy a new local SIM card



Limited profile switching

Frequently asked questions about eSIMs