An eSIM is a digital SIM built into your phone, so you add a plan by downloading it instead of inserting a card, and a physical SIM is the small card in the SIM tray. Apple says an iPhone can hold up to eight or more eSIMs, and Google says Pixel 3a and later phones can run one physical SIM and one eSIM at once. For travel, the eSIM is the easier option: keep your home number and add a local data plan without touching the tray.
If you work while you travel, the SIM question matters more than it used to, because some new phones no longer have a SIM tray at all. I read Apple's eSIM setup guide and Google's Pixel dual SIM help page. Here's what they say.
eSIM and physical SIM compared
| eSIM | Physical SIM | |
|---|---|---|
| Definition | A digital SIM built into the phone | A removable card in the SIM tray |
| Adding a plan | Download it from your carrier or a travel provider | Get a card and insert it |
| How many | Apple: up to eight or more stored on an iPhone | One per tray slot |
| Moving to a new phone | eSIM Quick Transfer on iPhone, if your carrier supports it | Move the card across |
| Dual SIM on Google phones | Pixel 7 or later can run 2 eSIMs if your carrier allows | Pixel 3a or later: one physical SIM plus one eSIM |
| Newest phones | Pixel 10 and later in the US, except the Pixel 10 Pro Fold, are eSIM-only | Not available on eSIM-only models |
| Needs | A phone and a carrier that support eSIM | A phone with a tray |
The detail that matters most: eSIM-only phones
Google's help page carries a line many people miss: in the US, if you have a Pixel 10 or later, except the Pixel 10 Pro Fold, you can only use an eSIM. Apple's page also refers to iPhone models that are eSIM-only in some countries and regions. So the choice is increasingly made for you by the phone. If you buy a phone abroad or bring one from home, check which SIM types it takes before you rely on picking up a local card.
How dual SIM works day to day
Google calls running two SIMs Dual SIM Dual Standby. You choose which SIM handles calls, messages and data. On a Pixel 8 or earlier, if you're on a call on one SIM, calls to the other go to voicemail. On a Pixel 8a and later you can use both SIMs for calls at the same time, as long as mobile data is on for both, automatic data switching is on for the second SIM and your carrier supports Wi-Fi calling on it.
On iPhone, Apple's guide says you'll need an iPhone XS, XS Max, XR or later and a carrier that supports eSIM. If your carrier supports eSIM Quick Transfer, you can move a SIM from your old iPhone to a new one without calling them, with both phones on iOS 18.4 or later, nearby, with Bluetooth on. Some carriers will also convert your physical SIM to an eSIM on the same phone.
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How to set up your phone for travel
- Check your phone supports eSIM and isn't locked to your carrier.
- Keep your home SIM, physical or eSIM, active for calls and texts such as bank codes.
- Add a travel eSIM for local data before you fly, while you're on Wi-Fi.
- Set the travel eSIM as your data line and your home SIM for calls and messages.
- Switch data roaming off on your home line so it isn't used by mistake.
For choosing the plan itself, see my guide to choosing an eSIM for international travel, and my look at whether Holafly is legit covers one of the popular providers.
My advice on eSIM or a physical SIM
If your phone supports it, use an eSIM for travel data and keep your main number on your home SIM. It saves hunting for a shop on arrival and you'll never lose a tiny card in a hotel room. The physical SIM still has a place if you swap phones often or your carrier doesn't support eSIM, but with eSIM-only phones arriving, it's worth getting comfortable with eSIM now.
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Frequently asked questions
What is the difference between an eSIM and a physical SIM?
An eSIM is a digital SIM built into the phone that you add by download, while a physical SIM is a removable card in the SIM tray. Both connect you to a carrier's plan.
Can I use an eSIM and a physical SIM at the same time?
On many phones, yes. Google says Pixel 3a and later phones can use one physical SIM and one eSIM at once, and Pixel 7 or later can run 2 eSIMs if the carrier allows.
How many eSIMs can an iPhone hold?
Apple's guide says you can manage up to eight or more eSIMs on an iPhone and switch between them.
Are some phones eSIM-only?
Yes. Google says that in the US, Pixel 10 and later phones, except the Pixel 10 Pro Fold, can only use an eSIM, and Apple refers to eSIM-only iPhone models in some countries and regions.
Is eSIM better for travel?
For most travellers, yes: you can add a local data plan before you leave and keep your home number active on your main SIM.
