How an eSIM works on iPhone: complete guide

What is an eSIM and how does it work on an iPhone?

An eSIM is a digital SIM card integrated into the iPhone's chip: instead of inserting a physical card, you save a line profile via a QR code or an operator link. The iPhone uses it just like a traditional SIM to connect you to the mobile network, without a tray or card that you can lose.

Technically, an eSIM (embedded SIM) is a chip soldered to the phone's motherboard. It doesn't come out, doesn't change, doesn't bend or scratch. What does change is the "profile" that lives inside that chip: a set of encrypted data that identifies your line to the operator's network. When you change operators or add a travel line, you don't change the chip: you install a new profile on the same hardware.

For the user, this translates into something simple: where before you had to find a SIM card ejector tool, get a physical card at an airport or store, and wait for the signal to "turn on", now you scan a code or tap a link and the line is ready on your phone in a matter of minutes. The iPhone can store several eSIM profiles at the same time (one for your usual line, another for a trip, another for work), although, depending on the model, only one or two can be actively transmitting data at a time. If this is the first time you've heard the term, the general explanation of what an eSIM is covers the technical basis in more detail, and the guide on how an eSIM works explains it without focusing on a particular phone.

Which iPhones are eSIM-compatible?

Apple introduced eSIM in 2018, so compatibility isn't about "recent" models but rather any iPhone from the last few years. The table summarizes what each iPhone family can do: install an eSIM, and have two eSIMs actively transmitting data at the same time (known as Dual eSIM).

Two important caveats before buying a travel eSIM. First, an iPhone might be locked to a single carrier (for example, if you bought it on installments with a local carrier); in that case, even if the model is eSIM compatible, the phone might reject profiles from other carriers until it's unlocked. Second, models sold in the United States from the iPhone 14 onwards no longer have a physical SIM tray: if your iPhone is from that region, eSIM isn't an option, it's the only way to have service. You can review full details on which phones accept eSIMs, beyond just iPhone, in the eSIM compatible phones guide.

How do I install an eSIM on an iPhone?

Installation takes a few minutes and doesn't require going to any store. These are the general steps; the operator you choose will give you the specific QR code or link:

1. Connect to Wi-Fi. This is the step most people skip and the one that causes the most problems: without internet, the iPhone cannot download the profile.
2. Open Settings → Cellular (or Mobile Data) → Add eSIM. On recent iOS versions, you can also directly tap the link or QR code sent by the operator, and the system opens this flow on its own.
3. Scan the QR code with your iPhone's camera, or tap "Use Mobile Data" if you received a link instead of a code.
4. Choose a name for the line (e.g., "Travel" or "Europe") to differentiate it from your usual line in the settings.
5. Define which line uses each function: The iPhone will ask you which line you want for calls, messages, and, most importantly, for default mobile data. This is where you choose the travel line to be the one that consumes internet.
6. Confirm and wait for activation. Normally, the profile is installed and active immediately; some operators activate the line with a small margin (minutes, not hours) from when you land or from the scheduled time.

If this is your first time installing an eSIM and you want step-by-step instructions with screenshots, the eSIM installation guide covers it for iOS and Android separately.

How to use eSIM and physical SIM at the same time?

All eSIM-compatible iPhones (from iPhone XS onwards) allow you to combine an eSIM with a physical SIM: this is the most common scenario for travelers, as they keep their usual number for calls and WhatsApp on the physical SIM, and use the eSIM only for mobile data in the destination country.

The settings are found in Settings → Cellular. There you will see the two lines listed separately, and three independent decisions:

• Default Mobile Data Line: which of the two uses the internet by default. For travel, it's usually best to choose the eSIM.
• Automatic Data Switching: an option that lets the iPhone switch between lines based on which one has better coverage at any given moment. This sounds convenient, but when traveling, it can backfire: if your Mexican SIM (or home SIM) loses eSIM signal for a second and the iPhone detects that it does have coverage on the physical line, it can automatically send data through it and activate roaming without you realizing it, even if you've set the eSIM as the default line. For a trip, it's best to disable automatic switching and keep the eSIM fixed as the sole data line.
• Default Line for Calls and Messages: typically, you'll leave this on your physical SIM, so you don't change your contact number while traveling.

The practical result: your WhatsApp, your bank verification SMS, and your calls still come through your usual number (as long as you have coverage or Wi-Fi), and data consumption—the one that really skyrockets abroad—runs on the eSIM you purchased for the trip.

What happens if my iPhone already has an eSIM and I add another one?

Nothing serious happens: the iPhone doesn't have any practical limit of just one eSIM. It can store several saved eSIM profiles at once (from different operators, from different trips), although only one or two can be actively transmitting data simultaneously, depending on whether the model supports Dual eSIM.

This means that if you're already using an eSIM as your primary line (for example, because your iPhone is a model without a physical tray) and you buy a data eSIM for a trip, the phone simply adds the new profile alongside the one you already had. Nothing is deleted, there's no need to "free up space." All you have to do is, again, decide in Settings → Cellular which of the lines uses mobile data while you're away, so that data consumption goes through the travel eSIM and not your usual line (which probably charges exorbitant roaming fees or simply doesn't have coverage in that country).

A related common question: when your trip ends, the data eSIM doesn't disappear on its own. It remains installed (inactive or expired) until you go into Settings and manually delete it, which is useful if you're returning to that destination and want to reactivate a new plan on the same profile.

Which is better for travel: eSIM or physical SIM?

It depends on how often you travel and how comfortable you are managing lines from your phone instead of holding a physical card. The table compares the two formats on the points that truly matter for a short trip.

The real question isn't which technology is "better" in abstract, but which one allows you to solve the problem before packing your bags instead of solving it in an airport line with your phone's battery nearly dead.

For multi-country itineraries on the same trip, an eSIM has an additional advantage: you can install the profile for the next destination while still in the previous one, and activate it right when you cross the border, without having to look for a new store at each stop. If you also want to compare this against the roaming offered by your home operator, the guide on eSIM vs. international roaming goes into detail about costs and coverage, and the comparison of eSIM vs. physical SIM elaborates on each criterion in the table above.

What are the disadvantages of an eSIM?

eSIMs are not perfect, and it's good to know their limitations before relying on one for a trip:

• Requires a compatible phone. If your iPhone is older than the XS, or is locked to a carrier that doesn't allow third-party eSIMs, this option is out.
• Installation requires internet. As explained in the installation section, without Wi-Fi (or data), the profile cannot be downloaded for the first time. You need to install it before leaving home, not when you get off the plane at the airport without Wi-Fi.
• Not transferable by copying and pasting. If you switch phones, in most cases you'll need a new profile (new QR) instead of simply moving the eSIM like you would a physical card.
• A single QR code typically works for only one device. If you scan it on one phone, you can't reinstall it as-is on another without requesting a new one from the operator.
• If the phone is lost, the line is lost with it. There's no physical card you can rescue from a broken phone and insert into another emergency device.

None of these disadvantages are exclusive to travel: they are limitations of how eSIM technology works in general, and they affect someone using it as their primary line at home just the same. You can review more specific cases (and their solutions) in the guide on common eSIM problems.

Practical example: a trip with an eSIM on iPhone

To make it less abstract, let's consider a specific case. Imagine you live in Mexico City and are taking a twelve-day trip to Italy and Portugal. You have an iPhone 13 and want to keep your Mexican WhatsApp number to stay in touch with your family, but you need mobile data to use maps, translate menus, and order a car via app in each city.

A few days before you travel, from your home and with Wi-Fi, you buy an eSIM for Europe and install the profile following the process in the previous section: Settings → Cellular → Add eSIM → scan the code. At that same moment, you define the new eSIM as the default mobile data line, and that calls and messages continue to come through your physical Mexican SIM. You don't activate the plan yet if your provider allows you to choose the start date; you leave it installed and ready.

Upon landing in Rome, you put your iPhone in airplane mode for a few seconds and then reactivate it (a simple trick to force it to search for a network again), confirm that the eSIM is working with data, and from that moment on you have internet without having visited any operator store or waited in line. When you cross into Portugal halfway through your trip, if your plan covers several countries, you don't have to do anything else; if you bought a plan only for Italy, you repeat the installation of a new profile for Portugal with the same ease.

Throughout the trip, your Mexican physical SIM remains in the phone, turned off for data (thus avoiding expensive roaming) but available for calls and SMS if your home operator allows it, and for returning to Mexico without having to reinstall anything: as soon as you land, the iPhone automatically starts using that line again.

How to choose how much data you need before traveling

The most common mistake isn't technical, it's a miscalculation: buying the smallest data package "to test" and running out of connection halfway through the trip, precisely when it's most needed (arriving at a new airport, looking for a hotel). As a reference, maps and GPS consume relatively little, while video streaming and long video calls are what drain a data package fastest.

Some simple questions help estimate before buying:

• Will you use GPS navigation every day (car, walking, public transport)?
• Do you need to make work video calls or just occasional messages and photos?
• Does your accommodation have reliable Wi-Fi, or will you rely on mobile data all the time?
• Is it a single-country trip or will you cross several borders?

Since installing an eSIM profile usually doesn't have a cost in itself (the cost is in the data plan you activate), it's best to install it before leaving home with a calm Wi-Fi connection and decide on the plan size closer to the travel date, when the itinerary is clearer.

Frequently asked questions

Conclusion

For a short trip or a multi-country journey, an eSIM on an iPhone solves the real problem of running out of data as soon as you land: you install it before leaving home, calmly using Wi-Fi, keep your usual number for calls and WhatsApp on your physical SIM, and set the travel eSIM as your default mobile data line. If your iPhone is an XS or later, you already have the necessary hardware; all that's left is to choose a data plan for your destination.

If you've never installed an eSIM, it's a good idea to start with the getting started guide for installing an eSIM (linked above, in the installation section) before your flight day, so you don't leave it until the last minute. And if you already know you need data for your next destination, you can check the available plans by country in the international eSIM collection, which covers over 200 destinations with activation in approximately 1 minute and 24/7 support by email and WhatsApp in all languages.

Written byMarc González Sáez Founder of PuraSIM. He oversees the blog guides, which are built from our wholesale provider's network data, official carrier and manufacturer documentation, and real questions from travelers. If you spot something wrong, write to him and he'll correct it.