Before a trip abroad, many people worry: "What if I forget to turn off roaming and come home to a huge phone bill?" This guide explains what international roaming is and where to switch it on or off on iPhone and Android. It also covers what to check before you leave, when you land, and when you get home, how to avoid the most common slip-ups, and when to use your regular plan versus a travel eSIM for your destination. It's written for first-timers. The short version: before you leave, pick one line for mobile data while you're abroad, and turn off data roaming on every other line. That one habit removes most of the risk of an unexpected bill. (These steps reflect typical settings as of September 2026. Menu names and features vary by device, OS version, and carrier.)
- Why data costs can climb abroad
- Where to find the settings on iPhone and Android
- What to check from departure to your return
- When to use roaming and when to use a travel eSIM
- What to check, in order, if you can't connect
Why can data get expensive abroad?
In short, high bills usually come from data your phone used on its own without you noticing, not from data you chose to use. If you use mobile data abroad on your usual plan, your carrier connects you through a local partner network. This is called international roaming. Roaming is often billed separately from your domestic plan, and the charges can add up quickly if you don't realize it's happening. Some plans include roaming, but the countries covered, data allowances, and day limits differ by carrier, so check your plan's terms before you go.
The traffic people miss most often is background data that runs while you aren't using your phone. For example:
- Automatic app updates (the more apps you have, the more data they use)
- Automatic photo and video backups to the cloud
- Map apps reloading map data
- Autoplay and auto-refresh in social media and news apps
- Email syncing and OS update checks
When people say "I barely used my phone, but the bill was huge," this kind of background data is usually the reason. The good news: if you decide in advance when to turn roaming on and which line to use it on, you can control most of it. For a broader look at managing phone costs, see our articles on saving on your phone bill.
Where do you turn roaming on or off?
You'll find it under Data Roaming in your phone's Mobile Data (or Mobile Network) settings. The exact path depends on your device and OS version, but it usually looks like this. Open the menu once before you leave so you aren't hunting for it after you land.
On iPhone
Go to Settings → Mobile Data (or Cellular) → Mobile Data Options (or Cellular Data Options) → Data Roaming. If you have more than one line, including an eSIM, each line has its own setting. You pick the line at the top of the screen first, so check which line you're editing before you flip the switch.
On Android
Look under Settings → Network & internet → SIMs (or Mobile network) → Roaming. Menu names and layouts vary by manufacturer and model. If you can't find it, type "roaming" into the search bar at the top of Settings.
If you use an eSIM alongside your regular SIM
Adding an eSIM gives your phone two or more lines. What matters most is which line you've set for mobile data. If it's still set to your original line, you could install a travel eSIM and still end up using data on your home plan. To switch, go to Mobile Data → Mobile Data on iPhone, or SIMs → Mobile data on Android. You can also check whether your device supports eSIM before you buy.
Name your lines so you don't mix them up
With more than one line, your settings may show labels like "Primary" and "Secondary," and it's easy to lose track of which is which. iPhone lets you rename each line, and most Android phones let you edit SIM names too. Names like "Home line" and "Travel eSIM" make it much harder to switch the wrong one when you change data or roaming settings abroad. It takes a few seconds and can save you stress later.
Turning off data roaming stops mobile data on that line while you're abroad, but Wi-Fi still works as usual. The right setup depends on whether hotel and café Wi-Fi is enough for you, or whether you also need data on the move, for example to check maps.
Data roaming off vs. mobile data off vs. airplane mode
These three settings sound alike but work differently. Mixing them up can mean you think data is off when it isn't, or you block data you actually need. Here's a simple comparison.
| Setting | What it stops | What still works | Best for |
|---|---|---|---|
| Data roaming off | Mobile data on that line while abroad | Wi-Fi and data on your other lines | Keeping your home line active without roaming charges |
| Mobile data off | All mobile data on that line | Wi-Fi | When you don't want to use mobile data at all, at home or abroad |
| Airplane mode on | All cellular connections (Wi-Fi and Bluetooth also turn off at first) | You can turn Wi-Fi back on while staying in airplane mode | Takeoff and landing, or when you want to be sure everything is off |
If you really want to avoid any extra data use, a simple option is to turn on airplane mode and then turn Wi-Fi back on by hand. A travel eSIM won't work in airplane mode, though, so when you need mobile data, turn airplane mode off and enable only the line you plan to use. Calling, texting, and roaming charges differ by carrier, so check your carrier's latest information for the details.
A checklist from departure to your return
The way to avoid a surprise bill is to split your prep into stages. If you try to do everything the night before, it's easy to miss something, so break it up like this.
| When | What to do | Why |
|---|---|---|
| A few days before you leave | Choose how you'll get online abroad (your carrier's roaming, a travel eSIM, or Wi-Fi), and check that your phone supports eSIM | Know what each line is for so you aren't deciding on the spot |
| By the day before | If you're using a travel eSIM, install it while you're still at home | Finish setup on a stable connection |
| Departure day (at the airport) | Temporarily turn off automatic app updates and photo backups | Prevent large data use you didn't intend |
| Before takeoff | Turn off data roaming on any line you won't use for data | Avoid unexpected charges on your home line |
| After you land | Turn on the line you'll use, then check the carrier name at the top of the screen and confirm data works | Make sure you're connected on the line you meant to use |
| When you get home | Switch mobile data back to your usual line, turn off the travel eSIM line, and turn auto-updates and backups back on | Return your phone to its normal setup |
Step three, pausing auto-updates and backups, usually makes the biggest difference. A single photo or video backup can use anywhere from a few hundred MB to several GB, which can be a large share of your data on a trip. If you're not sure how much data you'll need, browse the comparison page by destination, data amount, and number of days to find something close to how you use your phone. Prices, data amounts, and terms can change, so check the latest details before you buy. After your trip, check your next bill for any roaming charges you don't recognize. It also helps you fine-tune your settings for next time.
Common slip-ups and how to avoid them
Most data problems abroad don't happen because people can't find the setting. They happen because nobody checked which line is actually active. Here are the most common cases and how to prevent them.
You installed a travel eSIM, but data was still going through your home line
The eSIM was added, but mobile data was still set to your original line. When you land, check the carrier name at the top of your screen and which line is selected for mobile data in Settings. If your lines are named, this takes one glance.
Data roaming was on for both lines
People often don't realize each line has its own roaming setting, so roaming stays on for the home line too. Your phone normally uses whichever line you picked for mobile data, but to be safe, turn off data roaming on the line you aren't using.
You turned off roaming on the travel eSIM and lost your connection
This is the opposite mistake. Someone remembers "turn off roaming abroad" and switches it off for the travel eSIM as well, then can't get online. Because of how travel eSIMs connect to local networks, many need data roaming turned on. Remember: turn roaming off only on the line you're not using.
Both lines started using data as soon as you turned off airplane mode
When you turn off airplane mode after landing, every line on your phone starts searching for a signal at once. If roaming is still on for your home line, it may start using data without you meaning it to. Turning off roaming on unused lines before takeoff protects you here too. For prep tips based on how you travel, see our articles by travel type.
Roaming or a travel eSIM: which should you use?
As a rule of thumb, roaming suits short trips with light use, and a travel eSIM suits trips where you'll use a fair amount of data. There are two main ways to get mobile data abroad: roaming on your current plan, or adding an eSIM made for your destination. Each works best in different situations.
| Compare | Roaming on your current plan | Travel eSIM for your destination |
|---|---|---|
| Setup | Often works once you check a few settings | You buy and install it before you leave |
| Cost predictability | Can vary with how much you use | Easier to predict, since you choose data and days in advance |
| Phone number and SMS | You may be able to keep using your usual number | Mostly data-only plans (calls in apps like WhatsApp still work) |
| Best for | Very short stays, layovers, light use | Trips or business travel of several days or more, study abroad, long stays |
| Watch out for | Check which countries and terms are covered first | Check device compatibility and when to set it up |
You don't have to pick just one. In practice, the easiest setup is often to keep your home line active for your number and texts, and use a travel eSIM for data. For a closer look at how the costs compare, see Carrier roaming vs. a travel eSIM: which costs less? To see how other options stack up, browse our comparison articles.
Who's fine with roaming, and who's better off with a travel eSIM
The right choice depends on you. There's no need to switch if you don't have to, so see which description fits you better.
Roaming on your current plan is likely enough if you:
- Are staying only a day or two and mainly checking messages
- Only need data during an airport layover
- Have Wi-Fi where you're staying and rarely use data when you're out
- Have a plan that includes roaming and know its terms
A travel eSIM may give you more peace of mind if you:
- Are traveling for several days or more and use maps or ride-hailing apps every day
- Are studying abroad or on a long stay and can't easily predict your data use
- Want to choose your data up front so you know what you'll spend
- Need to stay in touch with family or travel companions while getting around
If you plan to stream video or make long video calls, a plan where you don't have to watch your data closely is another option. You can read how these plans work, and what to keep in mind, on our unlimited plan page. Even plans labeled "unlimited" may slow speeds after a certain amount of use, and they may come with a fair use policy or limits on tethering/hotspot use. Don't assume speeds will stay high no matter how much you use. Check the terms before you buy.
What to know before using a travel eSIM
With a travel eSIM, it's simple to use the eSIM for data abroad and keep data roaming off on your regular line. Setup is easy: tap the setup link you receive, follow the on-screen steps to add the eSIM, then turn the line on once you arrive. (If that doesn't work, manual setup instructions are available as a backup.)
A common question is whether it's OK to install the eSIM before you leave. In most cases, it's best to install it at home, where your signal and Wi-Fi are stable, then turn the line on after you arrive. When the plan activates depends on the plan, so check the instructions you get at purchase. You can see your eSIM details anytime in My Account.
Like many travel eSIMs, Bloomy is data-only. It doesn't include a phone number, so you can't make or receive regular calls or SMS on it. Calls through data-based apps like WhatsApp, Messenger, and FaceTime work as usual, so you can still call people. Plans are subject to a fair use policy, and speed and reliability depend on the local network, your device, and your location.
If you need SMS codes for banking apps or calls to your home-country number, plan ahead. Our phone number and SMS articles explain how to keep your home line active and what to do when you need your number. Before you go, list anything that depends on getting a text, like bank or account verification, so it doesn't catch you off guard. Whether your home line can receive texts abroad, and what that costs, depends on your carrier, so check before you leave.
Can't connect abroad? Check these in order
If you can't get online, you'll find the cause faster by checking one thing at a time. Work through this list from the top.
- Is airplane mode off? It's surprisingly common to land and leave it on.
- Is the right line selected for mobile data? Make sure it's set to the eSIM, not your home line.
- Is data roaming on for the line you're using? Many travel eSIMs need it on to connect to local networks.
- Is the line turned on? Make sure the eSIM line itself isn't switched off.
- Turn airplane mode on and off, or restart your phone. This can help your phone find a local network again.
- Select a network manually. If your phone doesn't find one automatically, try picking one yourself.
If you still can't connect, see our full troubleshooting guide. For setup or pre-purchase questions, check the FAQ, or contact us if you still need help. Speed and reliability depend on local network conditions, your location, and how busy the network is at that time. Coverage can feel different in cities and rural areas, so if the signal is weak, try moving a short distance.
Summary: check your settings once and travel with much less worry
Most surprise bills from abroad can be avoided by deciding two things before you leave: whether roaming is on or off, and which line you'll use for data. Find the settings before you go, turn off data roaming on lines you won't use, and use a travel eSIM or Wi-Fi for data. Give each line a clear job and you'll have far fewer moments of confusion abroad. Make switching everything back when you get home part of the routine, and your next trip will be even easier.
To find a plan for your destination, search by country, data amount, and number of days on Bloomy's comparison page. If this is your first eSIM, our eSIM guides walk you through setup and how to choose a plan, step by step.
This article describes typical settings and general guidance as of September 2026. Setting names, prices, and requirements vary by device, OS, and carrier, and may change. Before you buy or use a service, check its latest information.
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