Preparing your phone before an international trip
A short checklist for the week before you fly: compatibility, data, maps, banking and the settings that stop roaming surprises.
onesim team
Most connectivity problems abroad are set up at home. Ten minutes the week before you travel covers almost all of them. This is the list we’d give a friend; the detailed installation and troubleshooting steps live in Resources.
The week before
- Check your phone supports eSIM and is unlocked
- Buy and install your onesim package over Wi-Fi
- Download offline maps for each city
- Back up your phone
- Confirm your bank and 2FA apps work without SMS
- Set data roaming: on for onesim, off for your home SIM
Check compatibility first
Two things need to be true: the phone supports eSIM, and it is not locked to your home carrier. Most iPhones since 2018 and most recent Samsung Galaxy and Google Pixel phones qualify, but some regional models do not. The quickest way to be sure is the compatibility check, which also explains how to find your exact model number.
Choose how you’ll get online
| Home-carrier roaming | Local SIM at the airport | Travel eSIM | |
|---|---|---|---|
Set-up | Nothing, it just works | Queue, ID check, swap the card | Install at home over Wi-Fi |
Cost | Often high outside the EU; daily passes add up | Usually cheapest per GB for a single country | Flat rate; regional plans cover several countries |
Your number | Works as normal | Your home SIM is out of the phone | Home SIM stays in for calls and texts |
Multi-country trips | Depends on your plan | New SIM per country | One regional package |
If you are staying within the EU on an EU plan, roaming may already be included. For most other trips a travel eSIM is the least effort, and the multi-country case is where it clearly wins. Choosing a package covers country versus regional plans and how much data you need.
Install at home, activate on arrival
An eSIM installs over the internet, so do it on your home Wi-Fi where nothing can go wrong. Installing does not start your package; it starts the first time the line connects at your destination. Keep data roaming off for the onesim line until you land. The device-specific steps are in Installing onesim.
Maps, backups and the boring bits
Download offline maps for every city you will visit; they save data and work in the metro. Back up the phone before you leave, and make sure you can sign in to your email and bank from another device if the phone is lost. Write down or photograph your hotel addresses in the local script for taxi drivers.
On the plane
Nothing to do until you land. Then turn on data roaming for the onesim line, give it a minute to find a partner network, and you are online. If nothing happens, No signal at my destination lists the checks to run before you message us.
