How roaming charges happen
When you travel abroad, your phone cannot connect to your home network, so it connects to a partner network in the country you are visiting. That network carries your calls, texts and data, then bills your home provider, which passes the cost on to you. This is roaming, and the price depends entirely on your home plan.
Some plans include certain countries at no extra cost, some charge a daily fee for using your normal allowance abroad, and some charge for every megabyte, minute and text. Prices outside any included zone can be very high. Our guide to roaming charges goes into the different models in more detail; the point here is that you need to know which applies to you before you leave.
The surprises tend to come from a handful of places:
- Background data: apps sync, update and back up photos without you noticing, and a single cloud photo backup can use a lot of data.
- Incoming calls: in many places outside an included zone, you can be charged for answering calls, not just making them.
- Voicemail: if a call goes unanswered and diverts to voicemail, the diversion can be charged as an international call, and checking voicemail may cost more again.
- Ships and planes: ferries, cruise ships and aircraft sometimes carry their own mobile networks connected by satellite. These are usually outside any roaming deal and can be extremely expensive.
- Border areas: near a border, your phone may connect to a network in the neighbouring country, which may be billed differently from the one you are actually in.
Before you go: check your plan
Spend five minutes with your provider's website or app before you travel. Find out whether your destination is included in your plan, whether there is a daily roaming charge, what the fair-use limits are, and whether there is a spending cap or bill limit you can set. Many providers send a text with roaming rates when you arrive, but it is better to know in advance.
Check too whether your phone is unlocked, meaning it can accept a SIM or eSIM from another provider. Our guide to telling whether an iPhone is unlocked shows how to check in a few seconds.
Then decide on your approach. If your plan includes your destination at a reasonable cost, you may simply use it as normal. If not, you can either rely on Wi-Fi, or add a travel eSIM for data while keeping your home number available.
Airplane mode plus Wi-Fi
The simplest way to avoid roaming charges entirely is to switch on airplane mode as soon as you land, then turn Wi-Fi back on. Airplane mode cuts off all mobile network connections, so nothing can be charged by your home provider, but modern phones let you re-enable Wi-Fi and Bluetooth while it is on. Our guide to what airplane mode does explains exactly what it turns off.
With Wi-Fi alone you can still use messaging apps, make internet voice and video calls, browse, stream and use maps wherever there is a connection. Download offline maps beforehand, and the map will keep working with GPS when you are out of Wi-Fi range.
The trade-off is that you will be cut off whenever you leave Wi-Fi coverage, you will not receive ordinary texts and calls to your home number, and public Wi-Fi is not always reliable or secure. For a short city break this is often fine. For longer trips, road trips or anywhere you need maps and ride-hailing on the move, most people find it too limiting.
Wi-Fi calling
Wi-Fi calling is a feature offered by many providers that lets your phone make and receive normal calls and texts using your home number over a Wi-Fi connection instead of the mobile network. To the person calling you, nothing looks different.
Abroad, it can be very useful. If your provider supports Wi-Fi calling while roaming, you may be able to receive calls and texts on your home number in your hotel without connecting to a foreign mobile network. How those calls are billed, however, varies by provider: some treat them as if you were at home, others charge differently. Check your provider's terms before relying on it.
You can usually find the setting under the phone or mobile section of your settings. Turn it on at home, where you can confirm that it works, rather than for the first time abroad.
Using an eSIM for data while keeping your home number
Most recent phones support dual SIM, meaning two lines can be active at once, often a physical SIM and an eSIM, or two eSIMs. That lets you use a travel eSIM for mobile data abroad while keeping your home line switched on for calls and texts. A travel eSIM gives you mobile data abroad, typically for a set amount of data or number of days, without changing your home number.
The setup is straightforward. Install the travel eSIM before you leave, while you have reliable Wi-Fi. When you arrive, set the travel eSIM as the line for mobile data, and turn off data roaming on your home line so it cannot use data abroad. Leave your home line switched on if you want to receive texts, such as banking verification codes, but bear in mind that answering calls on it may still be charged under your home plan's roaming rules. Messaging apps and internet calls will use the travel eSIM's data.
Our guide to switching SIMs and using an eSIM on iPhone walks through the settings step by step, our eSIM vs roaming guide compares the two approaches, and our guide to how much data you need can help you choose a plan size.
Settings to check before you travel
Whichever approach you choose, a few settings make a big difference to how much data your phone uses and whether anything is charged by surprise. The names vary slightly between iPhone and Android, but the same options exist on both.
- Data roaming: turn it off for your home line unless you intend to use your home plan abroad. This is the most important single setting.
- Mobile data line: on a dual-SIM phone, make sure data is set to the line you intend to use abroad, and turn off any option that automatically switches data between lines.
- Default voice line and messaging: choose which line is used for calls, and check which number messaging services such as iMessage and FaceTime are linked to.
- Low data mode or data saver: reduces background activity and lowers streaming quality.
- Background app refresh and automatic updates: limit them to Wi-Fi, or turn them off for the trip.
- Cloud photo and video backup: set it to Wi-Fi only.
- Wi-Fi assist or adaptive connectivity: these features switch to mobile data when Wi-Fi is weak, which can use data without you realising.
- Voicemail and call forwarding: consider turning off voicemail or call diversion while you are abroad, or check with your provider how they are charged.
- Usage counters: reset your phone's mobile data counter when you arrive, so you can see how much you are using.