Bottom line: There are eight settings to change before an international trip. The first four exist to protect your bill; the last four exist to protect you. Most guides stop after the first group. That leaves real gaps: a data-only eSIM cannot dial local emergency numbers, handsets without VoLTE are refused service in some countries, and local emergency alerts will not reach you if the notification is switched off. Do all eight at home, on Wi-Fi, before you leave.
Travel phone settings fall into two groups with opposite goals
Search for phone settings for international travel and nearly every result ends at the same instruction: turn off data roaming. That advice is correct, but it serves a single purpose, which is avoiding an unexpected roaming bill.
The moments when your phone matters most, though, are different ones. You are lost, you are unwell, or your bag has been taken. What helps then is not a setting that blocks connectivity but a setting that guarantees it. The two goals point in opposite directions, so when they are mixed into one list, half of it quietly disappears.
This guide separates them.
- Protecting your bill: (1) per-line data roaming (2) choosing which line carries data (3) keeping your home number for calls and SMS only (4) throttling background traffic
- Protecting yourself: (5) securing a route to emergency services (6) enabling VoLTE (7) enabling local emergency alerts (8) preparing for theft and loss
Protecting your bill: how to handle eSIM and data roaming
Setting 1: switch data roaming per line, not per device
"Turn off data roaming" comes from an era when a phone held one line. The moment you install a travel eSIM, the phone holds two, and the setting is independent for each. Apple's own Dual SIM guidance has you select a line first, then open its cellular data options and set roaming there.
The correct state is not "off". It is this combination.
- Home carrier line: data roaming off
- Travel eSIM: data roaming on
Leaving the travel eSIM set to off is one of the most common reasons a new eSIM appears not to work on arrival. Leaving the home line set to on invites your phone to fall back onto an expensive network whenever the eSIM's signal dips.
Setting 2: pin cellular data to the travel eSIM and disable switching
iPhone offers a toggle called Allow Cellular Data Switching, which lets a non-default line carry data, typically while you are on a call. It is useful at home. Abroad it can pull your home line into a roaming session, so switch it off.
Then pin cellular data to the travel eSIM. On Android the equivalent lives under SIMs and network, or SIM card manager, where you set the default mobile data line. The full walkthrough is in our guide to setting up Dual SIM for travel.
Setting 3: keep your home number alive for calls and SMS
Putting the phone into airplane mode kills every line, including your home number. That is how travellers end up unable to receive the verification SMS that would unblock a frozen card.
Instead, turn off data roaming on the home line but leave the line itself enabled. Incoming SMS is normally free to the recipient, so verification codes still arrive. Incoming voice calls may incur international forwarding charges, so check your carrier's terms first. We cover the failure modes in receiving SMS verification codes on an eSIM.
Check the outgoing side too. If your default voice line has quietly become the travel eSIM, messages home may be sent from a foreign number, or fail outright on a data-only plan. Whether your plan carries a number at all is covered in does an eSIM come with a phone number.
Setting 4: throttle background traffic before you leave
Travel data allowances rarely disappear into video. They disappear into background sync. Turn off four things over cellular before departure.
- Automatic app updates
- iCloud Photos or Google Photos uploads
- Cloud backup over mobile data
- Wi-Fi Assist, which silently falls back to cellular when Wi-Fi is weak
On Android, marking the travel eSIM as a metered connection makes the operating system suppress large transfers on its own. Downloading maps in advance helps as well; see how to use offline maps abroad.
Protecting yourself: emergency calls, VoLTE and local alerts
Setting 5: decide in advance how you would call for help
This is the point most guides omit. A data-only eSIM cannot place a call to a local emergency number.
The reason is regulatory rather than technical. In Japan, the Ministry of Internal Affairs and Communications imposes the obligation to connect emergency calls on services that carry voice. Services that provide data alone fall outside that obligation. Most travel eSIMs are data-only, so no voice path exists on that line at all.
So arrange one of the following before you fly.
- Keep your home carrier line active with voice roaming enabled, and treat it as your emergency line
- Or choose a local plan that includes voice calling
Learn the local number as well. It is 112 across the EU, 911 in the United States and Canada, 000 in Australia, and both 999 and 112 in the United Kingdom. Japan's 110 and 119 do not work abroad.
Setting 6: turn VoLTE on, because 3G is gone in many countries
3G shutdowns are well advanced worldwide. In Australia the major carriers closed their 3G networks during 2024, which exposed a specific class of handset: devices that support 4G data but not VoLTE.
The ACMA, Australia's communications regulator, found that such devices could still carry data and ordinary calls yet could not reach Triple Zero. From 28 October 2024 it made rules requiring carriers to identify those handsets, notify the customer, and stop supplying service to them. In other words, a non-VoLTE phone is refused by the network outright.
The fix is simple. Before departure, enable VoLTE. On iPhone, open Cellular, select the line, and choose 4G with VoLTE enabled, or 5G, under voice and data. On Android the switch sits under SIMs and network as VoLTE or 4G Calling. If the option does not exist at all, the handset may be too old for some destinations. Device requirements are set out in how to check eSIM device compatibility.
Setting 7: make sure local emergency alerts can reach you
Most countries operate a public warning system. In the EU, Article 110 of the European Electronic Communications Code, Directive (EU) 2018/1972, requires member states to run one, and EU-ALERT delivers those warnings to handsets over Cell Broadcast. The United States has WEA, and Australia has its own emergency alert service.
These need no app and no registration. They are broadcast to every capable handset within the affected cells, and a roaming visitor's phone can be among them. But if you have switched emergency alert notifications off, nothing arrives. Plenty of people disable them at home and never think about it again.
On iPhone, scroll to the very bottom of the notification list to find Emergency Alerts. On Android, look under Safety and emergency, or Wireless emergency alerts. Alerts arrive in the local language, so an offline translation dictionary is a sensible companion.
Setting 8: prepare for theft, and know that the rules change abroad
Pickpocketing usually happens before any connectivity problem does, and settings help here too.
Apple's Stolen Device Protection applies extra checks when the iPhone is away from familiar places such as home or work. Viewing stored passwords requires Face ID or Touch ID with no passcode fallback, and changing your Apple Account password requires waiting an hour and authenticating again. Apple describes that delay as the window in which you can mark the device as lost. On a trip you are always away from familiar places, so the protection is permanently active. The corollary is that you cannot quickly change your passcode while travelling, which surprises people at the worst moment.
Android 15 and later add Theft Detection Lock, which locks the screen when sensors detect the phone being snatched, Offline Device Lock, which locks it when the device goes offline, and Remote Lock from a verified phone number. They live under Settings, Google, All services, Theft protection.
Finally, turn on Find My or Find My Device, and keep your eSIM QR code or activation details somewhere outside the phone, printed or reachable from another device. You will need them to reinstall a plan after losing a handset. For public networks, see whether free Wi-Fi abroad is safe.
The order to work through, and when to install the eSIM
Following this order means you verify everything once.
- Install the travel eSIM at home on Wi-Fi, since installation may not be possible on arrival
- Turn data roaming off on the home line and on for the travel eSIM
- Pin cellular data to the travel eSIM and disable data switching
- Confirm the default voice line is still your home number
- Enable VoLTE
- Confirm emergency alert notifications are on
- Throttle background traffic
- Enable Find My and theft protection
Activating the eSIM's line can wait until arrival, but installing the profile cannot. Coverage and plans by destination are listed on the Coral eSIM country plans page.
FAQ
Can I just leave airplane mode on the whole trip?
We would not recommend it. Airplane mode disables every line, so your travel eSIM stops working and verification texts to your home number never arrive. Setting data roaming per line is the modern equivalent and does the job properly.
Can I dial 112 or 911 from a data-only eSIM?
As a rule, no. The obligation to connect emergency calls attaches to services that carry voice, and a data-only service has no voice path. Keep your home carrier line available with voice roaming, or add a plan that includes calling.
My phone has no VoLTE option anywhere in settings
Either the handset predates VoLTE, or the manufacturer hides the toggle because it is always on. If it is the former, a country that has closed 3G may refuse the device entirely, as Australia's rules require. Give your model number to your carrier and confirm before you travel.
Will enabling emergency alerts flood me with notifications at home?
You will get more of them. A practical compromise is to enable them a few days before departure and revisit the setting after you return. Forgetting to enable them for the trip is the worse outcome.
Do these settings differ between Android and iPhone?
The names and locations differ; the eight goals do not. Android groups line selection under SIMs and network or SIM card manager, and theft protection under Google services. iPhone splits them between Cellular and the top-level notification list. Both let you set data roaming per line, which is the part that matters.
A travel settings list that stops at "turn it off" is only half a list
Advice about phones abroad grew out of bill shock, and it shows. Most articles are complete the moment data roaming is disabled. Yet the situations in which connectivity genuinely matters are not the ones where you are worried about the bill. They are the ones where you need an emergency number, or where a warning is being broadcast to everyone around you.
That territory is not decided by the handset alone. Regulators draw a line that leaves data-only services outside the emergency call obligation, countries that have closed 3G exclude non-VoLTE handsets by rule, and public warnings depend on a notification switch most people forgot they turned off. None of it can be written without going to primary sources. A settings list that skips the second four protects the traveller's bill and not the traveller.