An eSIM is a SIM card that is built into your phone instead of slotted in. Rather than collecting a plastic card, you download the mobile plan onto the phone. The plan does the same job a physical SIM does: it tells the phone which network to join and how to bill you.
How it works
Every eSIM phone has a small chip soldered inside it, identified by a number called the EID. A mobile operator can send a plan, called a profile, to that chip over the internet. You start the download by scanning a QR code, tapping an install link, or typing two codes: an SM-DP+ address (where the profile lives) and an activation code (which one is yours).
Once installed, the profile sits on the chip until you delete it. Most phones can store several profiles and switch between them in settings.
Why travelers use it
- Nothing to collect. You buy and install the plan before you leave, at home, on Wi-Fi.
- Keep your number. Your usual SIM stays in the phone. Calls and texts keep using your number while the eSIM carries your mobile data.
- Local rates, not roaming rates. A travel eSIM is a prepaid data plan for the country or region you visit, so you pay a fixed price up front instead of daily roaming fees. See Travel eSIM vs international roaming.
- One plan for several countries. Regional eSIMs cover a group of countries, such as most of Europe, in one purchase.
What it cannot do
- Most travel eSIMs are data only. They do not come with a local phone number. Use WhatsApp, iMessage or FaceTime over data, and your usual number for normal calls.
- It needs an eSIM-ready, unlocked phone. Check yours in 30 seconds: Does my phone support eSIM?
- It installs once. A profile cannot be moved to another phone, and most cannot be reinstalled once deleted. Delete it only after the plan has expired.
- It does not fix coverage. An eSIM rides on the same local networks as a physical SIM. Where those networks are weak, so is the eSIM.
eSIM and physical SIM side by side
| eSIM | Physical SIM | |
|---|---|---|
| How you get it | Download | Shop, kiosk or post |
| Swap between plans | In settings | Swap the card |
| Lose it | Nothing to lose | Easy to lose a tiny card |
| Works on | eSIM-ready phones | Phones with a SIM slot |
Still deciding how to get data on your trip? The best international phone plan for travel compares a carrier pass, a travel eSIM, a local SIM card and pocket WiFi, with real trip costs.
Getting started
- Check your phone supports eSIM and is unlocked.
- Pick a plan for your destination and trip length.
- Install it on the day you leave, before you go to the airport: iPhone guide, Android guide. On most plans the days start when the eSIM first connects in a covered country, and each plan states its rule.
- Switch data roaming on for the eSIM line when you land.