eSIM: What is it, and how does it work?

An eSIM is a digital SIM that’s built into most modern phones. It works like a physical SIM card, but without having to insert anything into your device. eSIMs offer tons of benefits, such as helping you avoid roaming fees and making it easy to switch between providers.

A happy woman activating her eSIM card on her phone.

What is an eSIM?

An eSIM is an embedded subscriber identity module — essentially, a built-in chip in your phone. It does everything a traditional SIM would do, but without having to slot a tiny card into your phone. Additionally, an eSIM allows you to use several carriers and phone numbers at once, which is super convenient.

eSIMs are available on smartphones, tablets, smartwatches, and even some cars! They’re great for quickly switching between phone numbers and grabbing mobile data for travel.

A man reviewing his Saily US eSIM plan on his phone.

How does an eSIM work?

An eSIM uses preinstalled software on your device to work just like a physical SIM. Once you activate it, you can connect to a cell network, make calls, and use mobile data. Most modern phones will have built-in eSIMs, but check our list of eSIM-compatible phones to see if yours does.

To start using an eSIM, just buy an eSIM plan and complete a quick setup. No need to remove your current SIM card — it can stay where it is, whether you decide to keep using it or not.

How to set up an eSIM

Follow these steps to start using an eSIM on your iPhone or Android.

Set up an eSIM on your iPhone with the Saily app

01

Pick an eSIM data plan for your trip

Select the country you’re heading to and choose a plan.

02

Download the Saily eSIM app

Get the app, tap “Install eSIM,” and follow the steps on the screen.

03

Your plan will automatically activate

Get ready for your trip — your plan will activate when you arrive.

 Set up an eSIM manually on your iPhone

  1. 1.

    Go to “Settings”.

  2. 2.

    Tap “Cellular data” or “Mobile data”.

  3. 3.

    Tap “Add cellular plan”.

  4. 4.

    Touch "Enter information manually" at the bottom of your iPhone screen.

  5. 5.

    Paste the eSIM information shared by your provider.

eSIM advantages

eSIMs are the future of connectivity. Here are the main eSIM benefits.

No high roaming fees

Travelers can buy eSIMs that connect them to local carriers and avoid unexpected roaming fees.

Multiple profiles

You can have multiple virtual eSIMs on one device, making it easy to switch between different carriers and phone numbers.

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.

Saves space

The absence of a physical SIM card slot frees up space for other device upgrades (like a bigger battery or more handset features).

Can’t get lost or stolen

Swapping out tiny SIM cards is tricky, especially if you’re on the move. An eSIM is built in, so it won’t get lost or stolen.

Less waste

A single plastic eSIM won’t destroy the planet, but getting a newly packaged SIM card for every trip adds up over time. Use an eSIM instead.

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

The main difference between an eSIM and a traditional SIM card is that an eSIM is digital while a SIM card is a physical chip.

eSIM

SIM

Phone numbers

Up to two*

Up to two

Network Operators

As many as you like

Up to two

Removal

Deactivate the profile

Remove the SIM card

Activation

Manual or automatic (plan activates at your destination)

Manual (need to insert a card into your device)

Compatibility

Newer devices only

Old and most new devices

Using abroad

Affordable — easy to get data plans for different countries

May be expensive due to roaming

*Saily is all about mobile data right now, so we don’t support phone numbers yet. Don’t worry — we’re working on it.

Get an eSIM data plan

Find a mobile data plan for your next trip — search our list of destinations.

Frequently asked questions about eSIMs