Your three options
There are three ways to have data abroad. Your home carrier's roaming pass is the simplest and usually the dearest, commonly around ten dollars a day to use your own number and plan. That is fine for a long weekend and real money over three weeks. Some US plans include slow international data at no charge, so check yours before buying anything. A local physical SIM is often the cheapest per gigabyte, but it costs you an errand on arrival day. A travel eSIM, which is a data plan you download, sits in between, and a week or two of regional data typically runs five to thirty dollars.
Setting up an eSIM
- Confirm that the phone supports eSIM and is carrier-unlocked, which the settings menu or your carrier can tell you.
- Buy a plan for the country or region and install it at home over wifi, because installation needs a connection.
- Switch the travel line on when you land and set it as the line for mobile data.
- Turn data roaming off on your home line, but leave the line itself on if you want to receive calls and texts.
- Ask your carrier how it bills incoming calls and texts abroad, since that varies by plan.
Most travel eSIMs are data only and come with no phone number. Calls go over internet calling apps or over wifi calling on your home line.
The two-factor trap
Banks text security codes to your US number. If that line is off, you can be locked out of your own money at the worst moment. Before you leave, move every account that allows it from text codes to an authenticator app or a passkey, save the backup codes somewhere you can reach offline, and test each login once.
What to download first
Do this on home wifi the night before: offline maps of every city on the route, the offline language pack for your translation app, boarding passes, reservations, and a copy of your passport data page and insurance policy. Save each lodging address in the local script for taxi drivers. Nearly all modern phone and laptop chargers accept 100 to 240 volts, which is printed on the charger, so you need only a plug adapter and not a voltage converter. Hair dryers are the exception.
Tip Carry a power bank of about ten thousand milliamp-hours in your hand luggage. A phone doing the work of map, ticket, translator and camera will not last a full travel day on its own battery.
