Guides
Keep your number. Use a travel eSIM for data.
Six settings, five minutes, and one of them has to be done before you leave the country.
Who wrote this
Priya Raman, Support Lead
Answers the queue these pages fail to answer, and rewrites the article whenever the same question arrives twice.
Responsible for
- The help centre
- Install and activation guides
- What travellers actually get stuck on
Reviewed by Jonah Reyes
What a travel eSIM actually is
A travel eSIM is a second line on your phone that carries data and nothing else. It has no phone number you would give to anybody, and it cannot make or receive normal calls or texts.
Modern phones hold two active lines at once. Your home line, which owns your number, and the travel line, which owns your data.
Nothing is removed and nothing is transferred. Your home SIM stays exactly where it is, physical or eSIM, and it keeps your number, your contacts, your messages and your authentication.
This is the part people get wrong before they buy. Adding a travel eSIM is not switching carriers. It is closer to plugging in a second, cheaper pipe for the traffic that costs the most.
The three settings that matter
Almost every roaming bill people receive after a trip comes from getting one of these three wrong.
First, data roaming must be OFF on your home line. This is the setting that costs money. Leave it on and your phone will happily use your home carrier's roaming data at their price while your travel eSIM sits idle.
Second, data roaming must be ON for the travel eSIM. This one confuses people, because it sounds like the expensive setting. It is not. The travel eSIM is a foreign profile by design, so from the phone's point of view it is always roaming, and turning that off simply stops it working.
Third, mobile data must be set to the travel line and voice must stay on your home line. Every dual SIM phone lets you choose which line does what.
Get those three right and the rest of this page is optional detail.
2 lines
active at once on every eSIM capable phone made since 2018
1 setting
that generates a roaming bill, and it is data roaming on the home line
0
changes to your phone number, your contacts or your messages
Settings, iPhone and Android
| What you are setting | iPhone | Android | Why |
|---|---|---|---|
| Turn off data on the home line | Settings, Mobile Data, tap your home plan, Data Roaming off | Settings, Network and internet, SIMs, tap the home SIM, Roaming off | This is the setting that generates a roaming bill. It is the only one that can cost you real money. |
| Turn on data for the travel eSIM | Settings, Mobile Data, tap the Orbislo plan, Data Roaming on | Settings, Network and internet, SIMs, tap the Orbislo SIM, Roaming on | A travel profile is foreign by design, so the phone treats it as roaming. Off means no data at all. |
| Choose which line carries data | Settings, Mobile Data, Mobile Data, select the Orbislo plan | Settings, Network and internet, SIMs, Mobile data, select Orbislo | Sends every byte down the cheap pipe while your number stays where it is. |
| Keep calls on your own number | Settings, Mobile Data, Default Voice Line, select your home plan | Settings, Network and internet, SIMs, Calls, select the home SIM | The travel eSIM has no usable number. Voice must stay on the home line. |
| Turn on wifi calling, before you leave | Settings, Apps, Phone, Wi-Fi Calling, on, then enter an emergency address | Settings, Network and internet, SIMs, home SIM, Wi-Fi calling, on | Most carriers will not let you enable this once you are abroad. This is the step that cannot wait. |
| Stop apps using the wrong line | Settings, Mobile Data, Mobile Data Options, Data Mode, and check Allow Mobile Data Switching is off | Settings, Network and internet, SIMs, Automatically switch mobile data, off | Automatic switching will quietly move you back to the home line when the travel signal dips. |
Menu names move between operating system versions. On iPhone the section is called Cellular in the United States and Mobile Data elsewhere. On Android, Samsung, Pixel and Xiaomi each word it slightly differently, but the path is always network settings, then SIMs, then the individual SIM.
Set up wifi calling before you leave
This is the one thing you cannot fix from abroad, and it is the reason people search for this page while sitting in a hotel room.
Wifi calling lets your home number make and receive calls and texts over any internet connection, with no roaming charge in most cases. It is what keeps your number genuinely usable on a trip rather than merely alive.
Most carriers require the phone to be registered on their home network to switch it on. Once you are abroad and your home line is not connecting, the toggle either fails or silently does nothing.
So turn it on at home, and then test it at home. Put the phone in airplane mode, turn wifi back on, and call somebody. If the call connects, wifi calling works. If it does not, fix it now rather than at an airport.
One extra step that matters in an emergency. Wifi calling asks for an emergency address, because a call to emergency services over wifi has no cell tower to locate you with. Fill it in with an address you can be found at.
The whole thing, in order
- At home, turn wifi calling on for your home line and enter an emergency address.
- Test it. Airplane mode on, wifi on, then make a call.
- Buy and install the travel eSIM before you fly, on your home wifi.
- Turn data roaming OFF on your home line.
- Turn data roaming ON for the travel eSIM.
- Set mobile data to the travel line and default voice to the home line.
- Turn off automatic data switching so the phone cannot move you back.
- Land, restart the phone once, and check the status bar shows two lines.
What to do per carrier
| Carrier | Wifi calling | Watch out for | Do this before you fly |
|---|---|---|---|
| AT&T | Supported, must be enabled while on the home network | International Day Pass activates automatically on any roaming use, at $12 a day | Turn wifi calling on, then ask support to block international roaming on the line entirely. |
| Verizon | Supported, needs an emergency address on file | TravelPass triggers on a single roaming byte or an answered call, at $12 a day | Enable wifi calling, add the emergency address, and disable TravelPass in the account settings. |
| T-Mobile US | Supported and on by default on most plans | Included roaming data is often capped at 128 kbps, which is slower than it sounds | Leave wifi calling on. Turn data roaming off anyway, because the free slow data will beat your fast travel eSIM to the connection. |
| EE, O2, Vodafone UK, Three | Supported on all four | European roaming may be included, but roaming outside Europe is charged per megabyte | Check whether your plan includes the countries you are visiting, then turn data roaming off for everywhere else. |
| Deutsche Telekom, Vodafone DE, O2 DE | Supported, sometimes needs enabling in the account portal first | Roaming inside the EU is included. Outside it, day passes are expensive | Enable wifi calling in the portal and on the handset, then turn data roaming off. |
| Telstra, Optus | Supported | Day passes activate on first use and are among the most expensive in the world | Turn wifi calling on, then switch international roaming off in the app. |
| Prepaid and small carriers | Often not supported at all | Wifi calling is the first feature a low cost carrier drops | Check before you rely on it. If it is missing, plan to take calls through a messaging app instead. |
Carrier features change. Check your own account before you leave rather than trusting a table on any website, including this one.
What still costs money
Keeping your number does not mean keeping it free. Four things can still charge you, and all four are avoidable.
An incoming call answered over the cellular network while abroad is roaming, and most carriers bill it. Over wifi calling it usually is not. The difference is whether the call comes in over wifi or over a foreign tower.
An outgoing international call from your home number is charged at your carrier's international rate, wifi calling or not. Use a messaging app for anything that is not urgent.
A text message you send is usually charged at an international rate. Incoming texts are almost always free, which matters for bank codes.
And voicemail is the trap. In some countries a call that goes to voicemail is billed as an incoming roaming call plus an outgoing one, because the network forwards it. Turn voicemail off for the trip if your carrier bills that way.
What happens to calls and texts while you travel
Your number keeps ringing. Somebody calling you gets through, on wifi if you have wifi calling and a connection, and over the foreign network if you do not.
Text messages arrive normally, including the ones from your bank. Incoming SMS is free on almost every carrier in the world, and it does not need mobile data.
Two factor codes still work, which is the single most common worry we get asked about. A code sent to your number reaches your number.
Apps that verify you by phone number, including messaging apps, stay signed in. They are tied to the number and not to the data connection carrying them.
What changes is which connection is doing the work. Data goes over the travel eSIM at travel prices. Calls and texts stay on the home line, ideally over wifi.
If you get it wrong
Two symptoms cover almost everything.
If you have no data at all, your mobile data line is probably still set to the home line with roaming off. Switch the data line to the travel eSIM and make sure roaming is on for that line only.
If you have data but a large roaming charge appears, the home line's data roaming was left on and your phone used it. Turn it off, and contact your carrier, because many will waive a first accidental charge if you ask within the billing period.
If nothing works at all after landing, restart the phone. An eSIM profile downloaded before departure sometimes needs one restart to attach to a foreign network for the first time.
Our support target is under 60 seconds, 24 hours a day, and every account carries 100 MB a month of free rescue data in 145 countries, which exists precisely so you can reach us when the thing you bought is not working.
Questions travellers ask
Will I lose my phone number if I use a travel eSIM?
Can I still receive calls and texts on my own number?
Why do I have to turn data roaming ON for the travel eSIM?
Do I need to set up wifi calling before I leave?
Will my two factor authentication codes still arrive?
What if my phone keeps switching back to my home carrier?
Does this work on an iPhone with a physical SIM?
What should I do if a roaming charge appears anyway?
Data on the cheap line, number on your own
Six settings and one purchase. Check the country you are going to first, then buy only the data you need.