UK eSIM Not Working? Complete Troubleshooting Guide

Your UK eSIM Isn’t Working – Let’s Fix It (UK eSIM Not Working After Arrival)

Most common UK eSIM problems can be resolved quickly without contacting customer support. Over 50% of issues are caused by data roaming being switched off, and most other problems resolve within minutes through manual network selection, APN configuration, a phone restart, or toggling aeroplane mode.

If you’re experiencing UK eSIM not working after arrival, the first thing to check is data roaming — it’s the single most common cause.

The Golden Rule: UK eSIM Data Roaming Not Working? Turn It ON

Before anything else, check this. It’s the single most common reason a UK eSIM won’t connect. When you arrive in the UK, your phone treats the UK mobile networks as a roaming destination, even if your profile is a local UK plan. Why? Because your phone doesn’t know your profile is local – it sees a SIM trying to use a network that isn’t its home network.

If your UK eSIM data roaming not working after toggling it on, try switching it off, restarting your phone, and then turning it back on to force a fresh connection.

On iPhone, go to Settings > Mobile Data > [Your UK eSIM] and toggle Data Roaming ON.

On Android, go to Settings > Connections > SIM Manager > [Your UK eSIM] and toggle Data Roaming ON.

If data roaming is off, your profile will show “No Service” or “Emergency Calls Only” regardless of signal strength. It’s not a network issue. It’s a setting. Fix that first, then move on.

Why Is My UK eSIM Not Working After Arrival? — 5-Step Diagnosis

Arrival is the moment of truth. You’ve landed, you’ve switched off aeroplane mode, and… nothing. Let’s diagnose this step by step.

Step 1: The Data Roaming Check

I know we said it above, but it’s worth repeating. Check data roaming is ON for your UK eSIM. Not for your home SIM. Specifically for the eSIM. This is the number one cause.

Step 2: The Network Selection Check

Your phone might be clinging to a network it knows (your home carrier’s roaming partner) rather than connecting to a UK network directly.

On iPhone: Settings > Mobile Data > Network Selection. Turn off Automatic, wait a few seconds, then select a UK network manually. Try EE, Vodafone, O2, or Three. One of them will work. Once you’ve got a connection, you can turn Automatic back on.

On Android: Settings > Connections > Mobile Networks > Network Operators. Search networks, then pick one manually.

Some eSIMs, including Roami’s, use auto carrier switching to handle this for you. But if yours doesn’t, manual selection is the quickest fix.

Step 3: The Aeroplane Mode Reset

Sometimes your phone’s modem just needs a kick. Turn on aeroplane mode, wait 10 seconds, turn it off. This forces your phone to re-register on the network. You’d be surprised how often this works.

Step 4: Restart Your Phone

Yes, the classic IT fix. But it genuinely helps with eSIM activation. A restart forces the profile to reload, and it clears any temporary network registration issues.

Step 5: Check your Profile Activation Date

Did you buy your profile in advance? Some eSIMs have a specific activation window. If you pre-purchased a plan that activates from a certain date, or one that activates upon first connection (common with Roami and similar providers), you might need to trigger the activation by connecting to data.

Check your profile purchase confirmation email for activation instructions. Some eSIMs require you to “activate” them in your account before they start working.

UK eSIM Activation Failed Error — What to Do Next

An activation failure usually happens during the setup process, when your phone is trying to download and install the profile. Here’s what to check.

A UK eSIM activation failed error typically means the profile download was interrupted, the QR code expired, or the device lost internet connectivity during setup.

The QR Code Expired

Most eSIM QR codes have an expiry window. If you bought your profile months ago and are only now trying to activate it, the QR code may have expired. Check your purchase email for the expiry date.

If it has expired, contact your provider. Most will reissue a new QR code if you explain the situation.

The QR Code Was Already Used

eSIM QR codes are single-use. If you scanned it on one device, you can’t use it on another. If you accidentally scanned it on an old phone, or if you’re trying to set it up on both a phone and an iPad, you’ll need a separate eSIM for each device.

Some providers (including Roami) offer QR codes that can be reused within a certain timeframe, but this is the exception rather than the rule.

Weak or No Internet Connection During Setup

To download an eSIM profile, your phone needs an internet connection. If you’re trying to activate while on a weak airport Wi-Fi or spotty cellular connection, the download may fail.

Fix: Connect to a stable Wi-Fi network before scanning the QR code. Alternatively, use your home SIM’s data to download the profile, then switch to the eSIM once it’s installed.

Device Incompatibility

Not all phones support eSIM. Even phones that do support eSIM may not support eSIM from all providers. Check that:

Your phone is carrier-unlocked (more on this below)
Your phone model supports eSIM (iPhone XS and later, Google Pixel 3 and later, Samsung Galaxy S20 and later, most 2020+ flagships)
Your specific phone variant supports eSIM (some Chinese and US models have different support)

Apple’s support page at support.apple.com/en-us/118670 has a full list of eSIM-compatible iPhones and iPads. For a comprehensive database of compatible devices, check GSMA’s eSIM device list.

The Fix: Manual Installation

If QR scanning keeps failing, try manual installation. Your provider should have given you an SM-DP+ address and an activation code alongside the QR code.

On iPhone: Settings > Mobile Data > Add eSIM > Enter Details Manually. Input the SM-DP+ address and activation code.

On Android: Settings > Connections > SIM Manager > Add eSIM > Enter activation code manually.

Manual entry bypasses the QR scanner entirely and often works when QR scanning doesn’t.

Why Does My eSIM Show No Service in UK? — UK eSIM No Signal Troubleshooting

“No Service” when you’re standing in a city centre is frustrating, but it’s almost always a configuration issue, not a network problem. Here’s what to check.

The most common fix for UK eSIM no service iPhone Android devices is ensuring data roaming is enabled and trying manual network selection to find a working UK network.

Is Your Phone in Aeroplane Mode?

It sounds obvious, but you’d be amazed how many people land, turn off aeroplane mode briefly, then accidentally toggle it back on while fumbling with bags and passports. Check the status bar.

Is Your Phone Locked to a Specific Carrier?

If your phone is carrier-locked (SIM-locked) to a non-UK carrier, a UK eSIM won’t work. Your phone will show “No Service” regardless of what you do, because it’s programmed to reject non-home SIMs.

How to check: Go to Settings > General > About > Carrier Lock. If it says “SIM Locked” or similar, your phone is locked. You’ll need to contact your original carrier to unlock it before the eSIM will work.

This is usually only an issue with phones bought on contract in certain countries (US, Canada, Japan). Most UK and European phones are sold unlocked.

For more on this, read our UK eSIM setup guide which covers device compatibility in detail.

The iOS Carrier Settings Update

Sometimes iPhones need a carrier settings update to work properly with a new network. If you’ve just installed an eSIM, go to Settings > General > About and wait a few seconds. If a carrier update is available, a popup will appear asking you to update. Tap Update.

Check Your APN Settings

Some eSIMs require manual APN configuration. This is especially common with data-only plans from smaller providers. Go to Settings > Mobile Data > Mobile Data Network and check if the APN field is populated.

If it’s blank, you’ll need to enter the correct APN details from your provider. We’ve got a full APN table below in the APN section.

UK eSIM Stuck on Activating — How to Fix It

An eSIM that’s stuck in an “Activating…” state for hours is a specific kind of pain. Here’s why it happens and how to fix it.

Why It Gets Stuck

The “Activating” state means your phone has downloaded the profile but is waiting for network registration to complete. This usually resolves within a few minutes, but sometimes it hangs because:

The network is congested – at busy times (arrivals at Heathrow, for instance), the network can be slow to register new devices
The profile is slightly corrupted – the download completed but with errors
There’s a network registration conflict – another SIM in your phone is interfering

Fixes to Try

Wait 15 minutes in a location with good signal – sometimes the network just needs time
Toggle aeroplane mode – forces a re-registration attempt
Restart your phone – clears the stuck state and starts again
Delete and reinstall – if nothing else works, remove the profile and add it again (instructions below)

Is It Really Stuck?

Some eSIMs take surprisingly long to activate fully. I’ve seen Roami eSIMs take up to 10 minutes on the first connection, especially during peak arrival times at major airports. giffgaff eSIMs can take hours to fully activate because they run manual ID checks.

If you’ve been waiting more than 30 minutes and nothing has changed, that’s stuck. Try the fixes above.

UK eSIM QR Code Not Scanning Fix — Common Reasons and Solutions

QR code issues are incredibly common, and they’re almost never your phone’s fault. Here’s the troubleshooting sequence.

The Simple Fixes First

Clean your screen. If you’re scanning from another phone or a printed piece of paper, smudges can interfere with the scan.

Adjust brightness. Turn your screen brightness to maximum if you’re scanning from another device. Low brightness makes QR codes hard to read.

Move closer or further away. QR scanners have an optimal distance range. Usually 10-20cm is about right, but try varying the distance.

Hold the camera steady. Obvious but worth saying.

The Not-So-Obvious Issues

The QR code is too small. If the QR code on your screen is tiny, zoom in on it before scanning. Your phone’s camera needs to see enough of the QR code to decode it.

The QR code is in a dark area of the image. Some eSIM emails place the QR code in a dark-coloured box or against a busy background. If your phone can’t read the code, try taking a screenshot of just the QR code and zooming in.

The Workaround: Manual Entry

As mentioned above, every eSIM with a QR code should also have an SM-DP+ address and activation code. Use manual entry instead of scanning. This bypasses the camera entirely and usually works when scanning fails.

The Nuclear Option: Different Device

If you absolutely cannot get the QR code to scan, borrow another phone. Install the eSIM on that device, then use the eSIM transfer feature (available on iPhone with iOS 18 and Samsung with One UI 6) to move it to your phone.

UK eSIM Not Connecting to Network — Steps to Try

This situation is different from “No Service.” You’ve got signal bars, but data isn’t flowing. This is almost always an APN or data roaming issue.

Data Roaming Confirmation

I’m saying it again because it’s that important. Check data roaming is ON for your UK eSIM specifically. Not your primary line. The eSIM.

APN Configuration

The Access Point Name (APN) tells your phone how to connect to the data network. If it’s wrong or missing, you’ll have signal but no data.

How to check on iPhone: Settings > Mobile Data > Mobile Data Network. If APN is blank, you need to enter it.

How to check on Android: Settings > Connections > Mobile Networks > Access Point Names.

UK APN Settings Reference Table

Here are the manual APN settings for the major UK networks. These work for 90% of eSIMs that use UK networks.

Network	APN	Username	Password
EE	everywhere	(leave blank)	(leave blank)
Vodafone	wap.vodafone.co.uk	wap	wap
O2	mobile.o2.co.uk	o2web	o2web
Three	three.co.uk	(leave blank)	(leave blank)
giffgaff (O2)	giffgaff.com	giffgaff	password
Lebara (Vodafone)	lebara.uk	(leave blank)	(leave blank)
Lyca (EE)	lycamobile.uk	lycamobile	plus
Tesco Mobile (O2)	tescomobile.uk	tescoweb	tescoweb
Sky Mobile (O2)	sky.uk	sky	sky

For eSIMs with auto carrier switching like Roami, the APN is usually provided automatically, but some eSIMs require you to enter a specific APN. Check your provider’s setup instructions carefully.

Still Not Working? Try These

Toggle data roaming OFF and ON again – this forces a fresh data session
Switch between 4G and 5G – Settings > Mobile Data > Voice & Data. Try limiting to 4G only; some eSIMs work more reliably on 4G
Reset network settings – Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings (this will forget Wi-Fi passwords)
Remove and re-add the eSIM – detailed instructions below

UK eSIM Slow Data Speed Fix — What to Check

So you’re connected, but everything feels sluggish. Web pages take forever to load, videos buffer, and you’re wondering if you bought a dud plan. Let’s fix that.

Why Is Your UK eSIM Data Slow?

Network congestion. London’s Canary Wharf at lunchtime, Edinburgh during the festival, Manchester on a match day – UK networks can get genuinely congested, especially in areas with lots of people.

You’re on the wrong network. Different networks perform differently in different locations. EE is fastest in cities, but O2 might be better in rural Wales. If your profile is locked to one network, you’re stuck with whatever that network’s performance is in your location.

Your plan is throttled. Many “unlimited” plans have fair usage policies that kick in after a certain data threshold. Check your plan details.

You’re on 4G when 5G is available. 5G provides significantly faster speeds in most UK cities. Make sure 5G is enabled in your settings.

VPN interference. If you’re running a VPN, your speeds will be limited by the VPN server’s capacity. Try disabling it temporarily to see if speeds improve.

How Roami Handles Speed

Roami’s auto carrier switching is specifically designed to address the network congestion problem. Instead of being locked to one network, Roami automatically switches between EE, Vodafone, O2, and Three to find the fastest available connection at your location. If EE is congested in your area, you’d automatically switch to Three or Vodafone without any manual intervention.

This is particularly valuable if you’re moving around the UK – network performance varies dramatically between cities and even between neighbourhoods. A single-network plan can’t adapt; Roami’s can.

Speed Fix Steps

Run a speed test – speedtest.net or the Ookla app. Note your speeds.
Check your network – which network are you connected to? Go to Settings > Mobile Data and look at the carrier name.
Try manual network selection – if your supports it, pick a different network and test again.
Toggle 5G on and off – Settings > Mobile Data > Voice & Data. Try 5G Auto, then 5G On, then 4G.
Check for data caps – log into your provider’s account portal and check your remaining data.
Try at different times of day – if it’s fast at 6am but slow at 6pm, it’s congestion.

When Slow Speeds Are a Coverage Issue

If you’re in a rural area, the Scottish Highlands, the Lake District, or similar, slow speeds might simply reflect limited infrastructure. Our UK eSIM coverage guide has detailed information on what to expect in different parts of the country.

UK eSIM APN Settings Not Working — Manual Configuration

You’ve entered the APN exactly as specified, but data still isn’t flowing. Let’s troubleshoot.

Common APN Mistakes

Typo in the APN field. Double-check every character. APN values are case-sensitive and punctuation-sensitive. “mobile.o2.co.uk” is not the same as “mobile.o2.uk” or “mobile.o2.co.uk " (with a trailing space).

Wrong field filled in. The APN goes in the APN field, not the Username or Password field. Sounds obvious, but easy to misread on a small screen.

Profile conflict. If you’ve installed multiple APN profiles (common with work MDM profiles or VPN profiles), they can conflict. Settings > General > VPN & Device Management. Remove profiles that aren’t needed.

iPhone APN field is locked. On some iPhones, the APN field is greyed out if certain carrier profiles are installed. If this happens, you may need to remove the eSIM and add it again, or contact your provider for a carrier profile that includes the APN automatically.

The Complete APN Reset

If APN issues persist:

Go to your profile settings and note down any existing APN values
Delete the APN entry entirely (leave blank)
Restart your phone
Re-enter the APN exactly as specified by your provider
Toggle data roaming OFF and ON
Test data

Using APN from Your Provider’s App

Some providers offer a configuration app that sets up APN automatically. For Roami users, the setup process includes step-by-step instructions with the correct APN for your specific plan. If you’re having APN trouble, check your provider’s app or setup portal first – they may have an automatic configuration option.

UK eSIM Dual SIM Conflict — Fixing Conflicts Between Home and UK Lines

Running two SIMs simultaneously is one of the best features of modern phones, but it can cause specific problems. Here’s how to diagnose and fix dual SIM conflicts.

What a UK eSIM Dual SIM Conflict Looks Like

One SIM has data but the other doesn’t
Calls go to the wrong line
SMS messages aren’t received on the expected line
One SIM shows “No Service” while the other works fine
Battery drains unusually fast

Common Conflicts and Fixes

SIM for Default Voice Line. If you have two active SIMs, calls and SMS may default to the wrong one. Check Settings > Mobile Data > Default Voice Line and set it to the SIM you want for calls and SMS.

Data Line Setting. Only one SIM can provide data at a time. Make sure your UK eSIM is selected as the data line. On iPhone: Settings > Mobile Data > Cellular Data. On Android: Settings > Connections > SIM Manager > Mobile Data.

iMessage and FaceTime. On iPhone, iMessage and FaceTime need to know which line to use. Settings > Messages > Send & Receive. Check that your UK number or Apple ID email is selected. Settings > FaceTime > Your FaceTime Contact Info.

WhatsApp Re-registration. If you switch the data SIM in your phone, WhatsApp may try to re-register. It shouldn’t affect functionality, but you may get a verification prompt.

The Proper Dual SIM Setup

We’ve written a complete guide to this, but here’s the quick version for avoiding conflicts:

Label your SIMs clearly (Settings > Mobile Data > [SIM name])
Set UK eSIM as the data line
Keep data roaming OFF on your home SIM
Enable “Allow Cellular Data Switching” on iPhone (this lets your phone use both lines for data if the primary one drops)
Set Default Voice Line to the SIM you want for calls and SMS

For step-by-step instructions with screenshots, read our UK eSIM dual SIM setup guide.

The “One SIM Not Registering” Problem

Sometimes when you insert a second SIM, one of them refuses to register on the network. This is usually caused by the phone being confused about which SIM to use for network registration.

Fix: Remove both SIMs (eSIM and physical), restart the phone, then add the UK eSIM first. Once it’s registered and showing signal, add your home SIM. This establishes the correct registration order.

UK eSIM No Signal Troubleshooting — Step by Step

You’ve got an eSIM installed, but the signal bars are empty or show a crossed-out circle. Let’s fix this.

Immediate Checks

Is aeroplane mode off? Check the control centre.
Is your phone in a building with thick walls? Some UK buildings (especially older stone buildings) block mobile signals. Try moving near a window.
Is your phone compatible with UK frequencies? Most modern phones support the frequencies used by UK networks, but some older phones or non-UK models may not. UK 4G uses bands 3, 7, and 20 primarily; 5G uses bands n28, n78, and n1.

Manual Network Selection

When you’re getting no signal, manual network selection is the most effective fix.

On iPhone: Settings > Mobile Data > Network Selection. Turn off Automatic. Wait for the network list to populate. Tap a network (start with EE, then try others). If it says “Unable to join network” or similar, try the next one.

On Android: Settings > Connections > Mobile Networks > Network Operators. Search. Tap a network.

Sometimes your phone will stubbornly refuse to connect to any network manually. This usually indicates one of three things: your phone is carrier locked, your profile hasn’t fully activated yet, or there’s genuinely no coverage at your location.

Coverage Gaps

It’s rare to have zero signal in UK cities, but it does happen in specific locations:

Underground (Tube stations between stops)
Some basement flats and ground-floor hotel rooms
Remote rural areas (Scottish Highlands, parts of Wales, Lake District valleys)
Large concrete or stone buildings (museums, some older hotels)

If you can’t get signal at your hotel, try stepping outside. If it works there, the issue is your building, not your eSIM. You can check predicted coverage using Ofcom’s coverage checker at ofcom.org.uk.

For more on UK mobile coverage, read our UK eSIM coverage guide.

Reset Network Settings

This is the last step before deleting and reinstalling the eSIM. It clears all network-related settings on your phone, including Wi-Fi passwords and Bluetooth pairings.

On iPhone: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings.

On Android: Settings > General Management > Reset > Reset Network Settings.

After the reset, you’ll need to reconnect to Wi-Fi and re-enter any APN settings, but it often resolves stubborn network registration issues.

UK eSIM Emergency Calls Only Problem — Why and How to Fix

Seeing “Emergency Calls Only” on your screen is worrying, but it usually doesn’t mean there’s something wrong with your phone. It means your phone has detected a network but hasn’t been allowed to register on it.

What “Emergency Calls Only” Actually Means

Your phone found a network and connected at a basic level, but the network rejected your SIM’s registration request. This could be because:

Your profile isn’t activated yet – the network doesn’t recognise your profile
Data roaming is off – your phone can see the network but won’t register for service
Your plan has expired – if your data plan has run out, the network may block registration
You’re in a restricted area – near military bases or other sensitive locations, networks sometimes block service
Your phone is carrier-locked – locked to a non-UK carrier

How to Fix It

Toggle data roaming ON (if you haven’t already)
Restart your phone
Try manual network selection
Check your eSIM’s activation status in your provider’s account portal
If nothing works, contact your provider’s support

UK eSIM Signal Drops Frequently — Likely Causes and Fixes

Signal that keeps cutting in and out is usually either a network coverage issue or a phone-side configuration problem.

Network handover problems. When you’re moving (on a train, in a car), your phone hands off between different cell towers. Sometimes this handover fails, and your phone takes a moment to reconnect. This is normal to some degree, but if it happens constantly, something’s wrong.

Network congestion. In very crowded areas, networks sometimes “drop” less active connections to free capacity for active ones. If you’re not actively using data, your connection may be dropped.

Roaming partner issues. If your profile uses a roaming agreement with a UK network rather than a direct connection, the roaming handshake can sometimes fail, causing a drop.

Battery saver mode. Some battery saver modes reduce background network activity. On Samsung phones, this can cause signal drops. Try disabling battery saver temporarily.

Dual SIM interference. We discussed this above, but it’s worth mentioning again – some phones struggle to maintain two active connections simultaneously, especially on older hardware.

iOS and Android updates. Occasionally, a system update introduces network bugs. Check if there’s a newer update available, or if others are reporting similar issues.

Fixes for Frequent Drops

Try 4G only – 5G handover can be less reliable than 4G, especially outside city centres
Toggle data roaming – forces a fresh registration
Reset network settings – clear all network configuration and start fresh
Update carrier settings – Settings > General > About (wait for update prompt)
Contact support – if your profile is corrupt, your provider can reissue it

UK eSIM Manual Network Selection — When and How

We’ve mentioned manual network selection several times, so let’s cover it properly. This is one of the most useful troubleshooting tools in your arsenal.

When to Use Manual Network Selection

You arrive in the UK and the eSIM isn’t connecting automatically
Your signal is weak and you want to try a different network
Your data speeds are slow and you suspect congestion on your current network
You’re getting “Emergency Calls Only”
You’re moving between regions and connection is dropping

How It Works

Your phone normally selects the network it thinks is best based on signal strength. But “best” for signal isn’t always “best” for data speeds, and sometimes your phone picks a network that doesn’t have a good roaming agreement with your provider.

By switching to manual, you can try each UK network individually and see which one works best.

Step-by-Step

iPhone: Settings > Mobile Data > Network Selection Toggle OFF “Automatic” Wait for the network list to appear (can take 30 seconds) Tap each network. Your phone will try to register. If it succeeds, you’ll see signal bars. If it fails, try the next one. Once you’ve found a working network, you can leave manual selection on.

Android: Settings > Connections > Mobile Networks > Network Operators Tap “Search Networks” Wait for the list to populate Tap a network to try it If it works, your phone will register. If not, try another.

Which Network Should You Pick?

Start with EE. It has the best overall coverage and speeds. If that doesn’t work, try Vodafone (good city coverage), then O2 (good rural coverage), then Three (good if you’re in a major city).

For eSIMs with auto carrier switching like Roami, you typically don’t need to do this, but manual selection is still available as a fallback.

UK eSIM Carrier Locked Phone Fix — What You Can Do

A carrier-locked phone presents one of the few eSIM problems that has no fix on the phone itself. If your phone is carrier-locked, a UK eSIM will not work – period.

How to Check

On iPhone: Settings > General > About > Carrier Lock. If it says “SIM Locked,” your phone is locked.

On Android: Settings > Connections > SIM Card Manager > SIM Lock Settings. If there’s an option to “Lock SIM card,” you may or may not be carrier locked – check with your carrier.

What to Do If Your Phone Is Locked

Contact your original carrier and request an unlock. In many countries, carriers are required to unlock phones for free after the contract ends.
Use a temporary unlock code – some carriers offer temporary unlocks lasting 30 days. Ask.
Buy a UK physical SIM – not ideal, but a physical SIM will work in a locked phone if it’s the same carrier’s network. A Three UK physical SIM might work on a Three-locked phone, but this is unreliable.
Get a different phone – if you have a spare unlocked phone, use that for the trip.

How Roami Handles This

Roami works on unlocked phones only. If your phone is locked, Roami’s eSIM won’t work either. We recommend checking your lock status before buying any eSIM.

UK eSIM Delete and Reinstall Profile — When and How

Sometimes nothing else works and you need to start from scratch. Here’s how to safely remove and reinstall your UK eSIM.

Performing a UK eSIM delete and reinstall profile is the last resort when activation is stuck, APN settings won’t save, or the profile appears corrupted.

How to Delete an eSIM Profile

On iPhone: Settings > Mobile Data > Tap the UK eSIM line > Delete SIM. Confirm.

On Android: Settings > Connections > SIM Manager > Tap the UK eSIM > Delete or Remove.

What Happens When You Delete

The profile is removed from your phone
You can reinstall using the original QR code – BUT only if your provider allows it
Any remaining data on your plan is usually preserved (check with your provider)
You will NOT lose your phone number if it’s a full-service plan (the number is tied to your account, not the profile)

Can I Reinstall UK eSIM If I Delete It?

Yes, in most cases – but it depends on your provider. Some providers let you reuse the original QR code. Others require a new one. For Roami, you can typically reinstall using the same QR code within the plan’s validity period.

If the QR code doesn’t work: Contact your provider’s support. They can generate a new QR code for you. Most providers, including Roami, offer live support for this.

When to Delete and Reinstall

Activation is stuck for more than 30 minutes
APN settings won’t save
The profile appears corrupted
You’ve tried every other fix and nothing has worked

App-Specific Connectivity Issues and Fixes

Sometimes data works generally, but specific apps don’t. This is usually not an eSIM issue, but here’s what to check.

iMessage Not Activating

If iMessage won’t activate with your UK number:

Settings > Messages > iMessage toggle OFF, wait 30 seconds, toggle ON
Settings > Messages > Send & Receive. Make sure your UK number and Apple ID email are checked
Settings > FaceTime > Make sure your UK number is selected
If it still won’t activate, try restarting your phone
iMessage activation can take up to 24 hours with a new number on some carriers

Banking Apps Not Sending SMS

If you can’t receive SMS verification codes from banking apps:

Make sure your UK eSIM is set as the default for SMS (Settings > Mobile Data > Default Voice Line)
Check that SMS works generally by sending yourself a test message
Some banks don’t support eSIM numbers for SMS verification – you may need to use a physical SIM
Try requesting the verification by voice call instead of SMS (many banks offer this option)

WhatsApp Registration

If WhatsApp won’t verify with your UK number:

Make sure WhatsApp can access SMS on your UK line
Request a voice call verification instead of SMS
If you’re keeping your original WhatsApp number, it should work fine over data

If you’re having ongoing issues, our UK eSIM setup guide has additional troubleshooting for specific apps.

Device-Specific Troubleshooting

Different phones have different quirks for eSIMs. Here’s what to check for specific brands.

iPhone-Specific Issues

iPhone 14 and later (US models): These iPhones have no physical SIM slot and rely entirely on eSIM. If your UK eSIM isn’t working on one of these, the troubleshooting steps are the same, but you have no physical SIM fallback. Make absolutely sure your UK eSIM is properly installed before you travel – you can’t just pop in a physical SIM as a backup.

iPhone 15 Pro/Max: These support faster 5G speeds on some UK networks. If you’re not seeing the speeds you expect, check that you’re connected to 5G (not LTE) and that your provider supports 5G access.

eSIM Quick Transfer: If you’re upgrading from an older iPhone to a newer one while in the UK, you can transfer your eSIM using iOS’s built-in Quick Transfer feature. Both phones need to be on iOS 16 or later, and both need to be nearby. Settings > Mobile Data > Add eSIM > Transfer from Nearby iPhone.

Dual eSIM on iPhone: iPhone 13 and later support two active eSIMs simultaneously. If you’re running two eSIMs (home + UK), the same dual SIM troubleshooting applies. Check that both lines are properly labelled and that the correct line is set for data.

Samsung-Specific Issues

Samsung Galaxy S20 to S23 series: These phones have a dedicated eSIM slot alongside the physical SIM. If your profile isn’t working, try a full device restart. Some Samsung phones need a restart after eSIM installation for the profile to fully register.

Samsung Galaxy S24 and later: These support dual eSIM (two active eSIMs, no physical SIM needed). The setup is in Settings > Connections > SIM Card Manager. If you’re having issues, check that eSIM is actually enabled for both slots – Samsung’s software sometimes defaults to physical SIM + eSIM mode even when you have two eSIMs installed.

Samsung Auto Data Switching: This feature is in Settings > Connections > SIM Card Manager > Auto data switching. It automatically switches between SIMs for the best data connection. If your UK eSIM data seems to be cutting out, this feature may be switching to your home SIM when the UK eSIM has weak signal. If your home SIM doesn’t have data roaming, this causes a data outage. Turn it off if you’re having intermittent connectivity.

Google Pixel-Specific Issues

Pixel 6 and earlier: These phones have known compatibility issues with some MVNOs. If your profile won’t activate on a Pixel 6 or older, try adding it through the Google Fi app or Pixel’s built-in eSIM manager rather than scanning the QR code directly.

Pixel 7 and later: Better support, but some users report APN configuration issues. Check that APN settings persist after a restart – Pixel phones sometimes reset APN entries on reboot.

Pixel’s eSIM as primary: If you’re using a UK eSIM as your primary (and only) line on a Pixel, make sure your emergency address is configured. Pixel phones require an emergency location address for eSIM-only operation.

OnePlus and Other Brands

OnePlus: eSIM support on OnePlus phones varies significantly by model and region. OnePlus 12 and later support eSIM well. Older models may not support eSIM at all, or only support it with specific carriers. Check your model’s specifications before buying an eSIM.

Xiaomi, Oppo, Huawei: These brands have inconsistent support. Some models support eSIM, many don’t. If your profile isn’t working on one of these phones, it’s more likely to be a compatibility issue than a configuration issue. Check the manufacturer’s specifications and your provider’s compatibility list.

Fairphone and other niche brands: Fairphone 4 and 5 support eSIM, but the implementation can be buggy. Make sure you’re running the latest software update.

Understanding UK Network Options for Better Troubleshooting

Knowing which network your eSIM uses helps with troubleshooting. Here’s a quick guide.

The Big Four UK Networks

EE – Fastest average speeds, best 5G coverage, good rural reach. Owned by BT.
Vodafone – Strong city coverage, good international roaming agreements. Owned by Vodafone Group.
O2 – Decent coverage, best in rural Wales and parts of Scotland. Owned by Virgin Media O2 (a Liberty Global/Telefonica joint venture).
Three – Good city speeds, aggressive pricing, weaker rural coverage. Owned by CK Hutchison Holdings.

How MVNOs and Providers Map to Networks

eSIM/Provider	UK Network
Roami	Auto-switches between EE, Vodafone, O2, Three
giffgaff	O2
Lebara	Vodafone
Lyca Mobile	EE
Tesco Mobile	O2
Sky Mobile	O2
Voxi	Vodafone
Smarty	Three
iD Mobile	Three
1pMobile	EE

This mapping is important because it determines which APN settings you need and which troubleshooting steps apply. For more detail on how these networks compare, read our UK eSIM network and MVNO guide.

UK eSIM Customer Service Contact — When to Call Support

You’ve tried everything in this guide. You’ve checked data roaming, tried manual network selection, reset network settings, and even deleted and reinstalled the eSIM. Still nothing.

It’s time to contact support. This is your UK eSIM customer service contact moment.

What to Have Ready

Your order number or account email
The eSIM ICCID (usually found in Settings > Mobile Data > [eSIM] about section)
Your phone model and iOS/Android version
A description of exactly what you’ve tried
Screenshots of error messages if possible

What Support Can Do

Check if your profile is properly activated on their end
Reissue a QR code or activation code
Check if there’s a known network issue in your area
Provide device-specific APN settings
Escalate to their network partner if necessary

Roami offers live support for all customers. If you’re stuck, contact us through the app or website and we’ll help diagnose the issue. Real person, real help.

Before You Give Up

One last thing to check: try your UK eSIM in a different phone. If it works in another device, the problem is your phone. If it doesn’t work in any device, the problem is your profile or its activation status. This simple test saves hours of troubleshooting.

And if you haven’t tried it yet, consider testing with Roami’s free trial to see if your device is compatible before committing to a paid plan. Use code web20 for 20% off any Roami UK plan once you’re confident everything works.

Specific Error Messages and What They Mean

Different phones show different error messages. Here’s how to decode the most common ones.

“No SIM Card Installed”

This error means your phone doesn’t detect any eSIM profile. This usually happens if:

The profile was deleted accidentally
The eSIM installation was interrupted
A software update reset the eSIM configuration

Fix: Reinstall the eSIM using your original QR code or activation code. If you don’t have the QR code, contact your provider’s support.

“SOS Only” or “Emergency Calls Only”

Your phone has detected a network but hasn’t been authorised to use it. As discussed above, this is usually a data roaming or activation issue. But there’s another possibility: your plan may have expired. Check your account portal to confirm the plan is still active.

“Unable to Activate eSIM”

This error appears during installation and means your phone couldn’t download the profile from the server. Try:

Connecting to a different Wi-Fi network (the one you’re on may be blocking the connection)
Using manual entry instead of QR scanning
Waiting 15 minutes and trying again (server issues are sometimes temporary)
Contacting your provider to check their activation servers

“Cellular Data Network Not Available for This Line”

You’ll see this on iPhone when the APN settings aren’t configured correctly. Go to Settings > Mobile Data > Mobile Data Network and enter the correct APN details for your provider.

“This eSIM Cannot Be Added to This iPhone”

This error is a compatibility issue. It could mean:

Your iPhone model doesn’t support eSIM (unlikely if it’s an XS or later)
Your iPhone is carrier-locked and the eSIM is from a different carrier
The profile is for a different region or device type
Your iOS version is too old for this particular eSIM

Fix: Update iOS to the latest version, check your carrier lock status, and confirm with your provider that your specific iPhone model is supported.

“iMessage Activation Failed”

Not strictly an eSIM error, but common when adding a new SIM. This usually resolves within 24 hours. If it persists:

Settings > Messages > Toggle iMessage OFF, restart, toggle ON
Make sure your phone number is checked in Settings > Messages > Send & Receive
Contact Apple Support if it doesn’t resolve within 48 hours

Roami-Specific Troubleshooting

Those using a Roami UK eSIM will find these provider-specific notes helpful.

Roami Auto Carrier Switching

Roami’s key feature is automatic switching between EE, Vodafone, O2, and Three. If you’re having connectivity issues:

Give it a minute to switch: After connecting, Roami’s system takes 30-60 seconds to assess the available networks and select the best one. If you don’t have a connection immediately, wait 60 seconds before troubleshooting.
Manual override: If auto-switching isn’t picking the best network for your location, you can override it by using manual network selection. Pick any UK network and see if performance improves.
Network congestion: In extremely crowded areas (concerts, stadiums, major events), all networks may be congested. Roami’s auto-switching helps by moving you to the least congested network, but in extreme cases, speeds may still be slow for everyone.

Roami APN Settings

Most Roami eSIMs configure APN automatically, but if you need to enter it manually:

APN: roamidata
Username: (leave blank)
Password: (leave blank)

If these don’t work, check your Roami account dashboard for the specific APN details for your plan.

Roami Live Support

Anyone who has tried everything and still cannot connect will find that Roami offers live customer support. Contact us through the website or app. Have your order number and a description of what you’ve tried ready. Our team can check your eSIM’s activation status, reissue a QR code if needed, and walk you through device-specific configuration.

Quick Fix Summary: The 5-Step Recovery Plan

Turn on Data Roaming for your UK eSIM. This fixes over 50% of all eSIM problems.
Manual network selection. Pick EE, Vodafone, O2, or Three. One will work.
Restart your phone. Clears registration issues.
Check APN settings. If they’re blank, enter the correct APN from our table above.
Toggle aeroplane mode. Quick reset of the cellular modem.

Everything else in this guide covers edge cases. Start with these five and you’ll be connected within minutes in the vast majority of cases.

For more detailed setup instructions, read our complete UK eSIM setup guide. And if you’re running a dual SIM setup, our dual SIM guide has specific troubleshooting for that configuration. If you haven’t picked a UK eSIM yet, the setup guide also covers how to choose the right plan for your needs.

Safe travels, and don’t let a connectivity hiccup ruin your trip.

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Roami Team