There are two ways to get mobile data abroad without hunting for a local SIM shop: let your home carrier roam, or add a travel eSIM. Both work. They charge very differently.
How roaming charges you
Your home carrier connects you to a partner network abroad and bills you for it. Three common models:
- A daily pass. Many US and Canadian carriers charge a fixed fee per day you use your phone abroad, on top of your monthly plan. It adds up fast on a two-week trip.
- Included roaming. Some plans include data in certain countries. Within the EU, roaming between member states is at domestic prices for EU plans. The catch is usually a fair-use limit or a short list of countries.
- Pay as you go. No pass and no included allowance means per-megabyte rates. This is how surprise bills happen.
Check your own plan's roaming page before you fly. It is the only reliable source for what you will pay.
How a travel eSIM charges you
You buy a data plan for the country or region you are visiting, for a set number of days. You pay once, up front. When it runs out, it stops; it never bills you more. Your usual SIM stays in the phone for calls and texts.
Plans come in three shapes:
- Fixed data: for example 10 GB to use over 15 days.
- Daily data: a set amount each day. Once you pass it, speed drops for the rest of the day until it resets.
- Unlimited: no cap on volume, usually with a fair-use speed limit after a set amount each day.
When roaming wins
- Your plan already includes the country at no extra cost.
- The trip is a day or two, and the daily pass costs less than the cheapest eSIM.
- You need your number to receive calls and texts while using data constantly, with no setup at all.
- Your phone is carrier-locked or has no eSIM (check here).
When a travel eSIM wins
- Trips of more than a few days, where a per-day pass multiplies.
- Countries your plan does not include, or includes at pay-as-you-go rates.
- Multi-country trips, where one regional eSIM covers them all. To choose between a regional and a global plan, see best eSIM for international travel.
- Anyone who wants a fixed cost and no chance of a bill after the trip.
For all four options side by side (carrier pass, travel eSIM, local SIM card and pocket WiFi), with real trip costs, see the best international phone plan for travel. If you would rather have a physical card, travel SIM card or eSIM? covers where to buy one.
Can I use both?
Yes, and this is the usual setup. Keep your home SIM on for calls and texts, with its data roaming switched off, and put mobile data on the eSIM. You still receive calls on your number. Your home carrier may charge to answer them abroad, so check its rates if you expect many. For bank codes and WhatsApp on your usual number, see will I get texts with a travel eSIM?
Avoiding a surprise bill
- Switch data roaming off on your home SIM before take-off.
- Turn off automatic data switching, so a weak signal never moves data back onto your home SIM.
- Check your carrier's app after the first day for any roaming charges.
Every switch, step by step: how to avoid international roaming charges.
Setting one up takes a few minutes: see the guides for iPhone and Android.