eSIM not working abroad? A troubleshooting checklist for iPhone

Q: How do I fix PDP Authentication Failure on iPhone?

Check the APN in Settings › Cellular › travel line › Cellular Data Network matches what your eSIM provider lists, remove old APN or configuration profiles in Settings › General › VPN & Device Management, turn off any VPN, then restart. If it persists, contact your eSIM provider.

If your travel eSIM isn't working after you land, it's nearly always one of three settings: the travel line isn't set as your cellular data line, Data Roaming is off for that line, or the phone hasn't searched for a network since you switched. Fix those, toggle Airplane Mode, and most eSIMs connect within a minute or two. The same three steps are in the Cabin Mode app's support section, because they sort out the large majority of cases.

If that doesn't do it, work down the rest of this list in order. Each check takes under a minute, and they're arranged so the likely causes come first.

Settings paths below use US English. In some regions Cellular is labelled Mobile Data or Mobile Service; the screens are the same.

First: what are you actually seeing?

The symptom narrows it down fast.

What you see	Most likely cause	Jump to
"No Service" or "SOS" on the travel line	Not registered on a network yet	Checks 3, 4, 6
Signal bars, but nothing loads	Wrong data line, Data Roaming off, or APN	Checks 1, 2, 5
"PDP Authentication Failure" alert	APN or profile settings	Check 5
The travel line isn't listed at all	Profile not installed, or deleted	Check 8
"SIM not supported" or "SIM Locked"	Carrier-locked phone	Check 7
Worked yesterday, stopped today	Data used up or plan expired	Check 9

1. Set the travel line as your cellular data line

Go to Settings › Cellular › Cellular Data and tap the travel line. An iPhone uses one line at a time for data. If it's still set to your home line, your travel eSIM can have full bars and do nothing.

While you're in Settings › Cellular, also check that the Cellular Data switch at the very top is on. It turns off mobile data for every line, and it's easy to flip without noticing.

2. Turn Data Roaming on, for the travel line only

Go to Settings › Cellular, tap the travel line, and turn Data Roaming on.

A travel eSIM connects to local partner networks, so iOS treats it as roaming even in the country it was bought for. With Data Roaming off, the line registers but won't pass data. This is the single most common reason a travel eSIM "doesn't work".

Then tap your home line and make sure Data Roaming is off there. That's what keeps your home carrier from billing you. See how to avoid roaming charges on iPhone.

3. Toggle Airplane Mode

Turn Airplane Mode on, wait ten seconds, turn it off. This forces the phone to drop whatever it was trying and search again from scratch. If you installed at home and flew several time zones, the phone may still be trying to find your home network's partners. A fresh search sorts that out.

If Airplane Mode doesn't do it, restart the iPhone. Same idea, more thorough.

4. Give it a few minutes, then check network selection

Some networks take a few minutes to admit a new profile the first time it appears on them. Sitting on a plane at the gate, or in a basement arrivals hall, doesn't help. Walk somewhere with a clear view of the sky and give it five minutes.

If it still says No Service:

Go to Settings › Cellular, tap the travel line, then Network Selection.
Turn Automatic off. The phone scans and lists the networks it can see. This can take a minute.
Pick a network listed as supported on your plan. In Cabin Mode, the plan screen shows the network.
If it connects, you can leave it or turn Automatic back on.

Manually picking a network helps when the phone keeps trying one that doesn't have an agreement with your eSIM's operator. If the list is empty, you're somewhere with weak coverage; move and try again.

5. Check the APN (and fix "PDP Authentication Failure")

The APN (Access Point Name) tells the phone which gateway to use for data. Most travel eSIMs set it automatically. When it's wrong or missing, you see bars and no internet, and sometimes an alert saying PDP Authentication Failure.

Go to Settings › Cellular, tap the travel line, then Cellular Data Network.
Compare the APN field with the one your eSIM provider lists. If your plan doesn't list an APN, it doesn't need one entered manually.
If the field is empty and your provider gives an APN, type it in exactly, lowercase included, in the Cellular Data section.

Two related causes of PDP errors:

A leftover configuration profile. VPN apps, work profiles and old carrier APN profiles can override settings. Check Settings › General › VPN & Device Management. Remove any APN profiles you installed for a past trip. Don't remove a work profile without checking with whoever manages it.
A VPN. Some VPNs block the connection before it's established. Turn it off, get connected, then turn it back on.

If you can't see Cellular Data Network at all, the eSIM's operator has locked the APN. That's normal, and it means the APN isn't your problem.

6. Update carrier settings, then reset network settings

Go to Settings › General › About and wait on that screen for about ten seconds. If a carrier settings update is available, a prompt appears. Accept it.

If nothing else has worked, reset network settings: Settings › General › Transfer or Reset iPhone › Reset › Reset Network Settings. This leaves your eSIMs installed, but it forgets saved Wi-Fi networks and passwords and removes Bluetooth pairings, so do it last. After the restart, redo checks 1 and 2, because it can reset some cellular choices too.

Never delete the eSIM as a troubleshooting step. A profile can be downloaded once. Deleting it spends it, and it can't be reinstalled from the same QR code.

7. Check the phone isn't carrier-locked

If iOS says "SIM not supported", or the eSIM wouldn't install in the first place, the phone is probably locked to your home carrier. Go to Settings › General › About › Carrier Lock.

No SIM restrictions: unlocked. Not your problem.
Anything else: the phone only accepts your carrier's SIMs. Only your carrier can unlock it, and it's much easier to arrange before a trip than during one. More in which iPhones support eSIM.

8. Confirm the line is actually installed and turned on

In Settings › Cellular, you should see the travel line listed under SIMs (or Cellular Plans on older iOS). Tap it and check Turn On This Line is on. It's possible to turn a line off by accident, especially when switching lines around.

If the travel line isn't there at all, the install didn't complete. Open the Cabin Mode app, find the eSIM and use Install again, or fall back to the QR code or manual details on the same screen. As long as the profile was never successfully downloaded, it's still available to install.

9. Check your data and validity

If it worked and then stopped, look at the eSIM in the app:

Data used up. Top up from the eSIM screen. It adds data to the same line, with nothing to reinstall.
Plan expired. Validity counts down continuously from activation. Once it's expired the line stops, and a top-up won't revive it; you'd need a new plan.
Usage lag. Usage figures come from the network operator and lag one to three hours. If you've just streamed on a train, the app may show more left than you really have.

Daily plans have a separate wrinkle: once the day's allowance is gone, the line may slow down sharply until the daily reset rather than stop. See unlimited vs fixed data eSIMs.

10. Specific things that break data

A few less obvious causes:

Low Data Mode or Low Power Mode can pause background refresh, so apps look broken when the connection is fine. Check Settings › Cellular › travel line › Data Mode.
Cellular data turned off per app. Scroll down in Settings › Cellular to the app list. If an app's switch is off, it only works on Wi-Fi.
iCloud Private Relay occasionally struggles on some networks abroad. Turning off Limit IP Address Tracking in Settings › Cellular › travel line pauses Private Relay on that line only. See if pages load.
5G flakiness. In areas with patchy 5G, forcing LTE sometimes gives a steadier connection: Settings › Cellular › travel line › Voice & Data › LTE.
You're in a place with no coverage. It happens. Mountain valleys, ferries, long tunnels and rural stretches all have gaps. Offline maps are worth downloading before you set out.

When to contact support

If you've been through checks 1 to 9 in a place where local phones clearly work, get in touch from the app. Useful things to include: where you are, what the status bar shows for the travel line, whether you see any alert, and a screenshot of Settings › Cellular. If the fault is ours or the network's, you get a refund or a replacement.

Before your next trip

Most "not working" problems are avoidable at home:

Check the phone is unlocked.
Install the eSIM on Wi-Fi a day or two before you fly (step by step).
Label the lines clearly ("Home" and "Travel") so you pick the right one when you land. Dual SIM on iPhone covers the rest.
Screenshot the APN and network from the plan screen, in case you need them offline.

Frequently asked questions

Why does my eSIM say No Service?

The phone hasn't registered on a network for that line yet. Turn Data Roaming on for the travel line, toggle Airplane Mode, and wait a few minutes somewhere with good signal. If it still says No Service, turn off Automatic in Network Selection and pick a supported network manually.

Why do I have signal bars but no internet on my travel eSIM?

Usually the travel line isn't set as the cellular data line, or Data Roaming is off for it. Check Settings › Cellular › Cellular Data, then the Data Roaming switch on the travel line. If both are right, check the APN.

How do I fix PDP Authentication Failure on iPhone?

Check the APN in Settings › Cellular › travel line › Cellular Data Network matches what your eSIM provider lists, remove old APN or configuration profiles in Settings › General › VPN & Device Management, turn off any VPN, then restart. If it persists, contact your eSIM provider.

Should I delete and reinstall my eSIM if it's not working?

No. An eSIM profile can only be downloaded once, so deleting it usually means it's gone for good. Try every other check first, and contact support before deleting anything.

Does turning on Data Roaming for my travel eSIM cost extra?

No. A travel eSIM is prepaid, and connecting to partner networks is how it's designed to work. The line that can cost you money is your home line, so keep Data Roaming off on that one.

Will resetting network settings delete my eSIM?

No. Reset Network Settings keeps installed eSIMs. It does forget Wi-Fi passwords and Bluetooth pairings. Erase All Content and Settings is different: it asks whether to keep or delete eSIMs, so read that prompt carefully.