You leave Wi-Fi.
Open Safari.
Nothing.
Messages stop sending. Apps refuse to refresh. Maps can't load directions.
Your iPhone may show 5G, LTE, 4G, or another cellular indicator, but somehow you still don't have working internet access.
Or maybe there's no cellular connection showing at all.
Before assuming your carrier is down—or that something is wrong with your iPhone—there are several things worth checking.
Cellular data problems can come from:
- Cellular Data being disabled
- Poor carrier coverage
- Airplane Mode
- Carrier outages
- SIM or eSIM problems
- Individual app permissions
- VPN configuration
- Data roaming settings
- Carrier settings
- iOS problems
- Network configuration
- Problems with your wireless account
Let's isolate the problem before resetting anything.
First: Make Sure Wi-Fi Is Actually Off
This sounds obvious, but it's an important diagnostic step.
If you're trying to test cellular data, temporarily disconnect from Wi-Fi.
Go to:
Settings → Wi-Fi
Turn Wi-Fi off temporarily.
Now open Safari and try loading a website.
You want to know whether your iPhone can reach the internet using the cellular network alone.
Cellular Works
Great.
Your cellular connection isn't the problem.
If internet access fails only while using Wi-Fi, start with our iPhone Connectivity Help guides:
iPhone Won't Connect to Wi-Fi? Here's How to Fix It
or:
iPhone Connected to Wi-Fi but No Internet? Here's What to Do
Cellular Doesn't Work
Continue below.
1. Make Sure Cellular Data Is Turned On
Start here.
Open:
Settings → Cellular
Depending on your region, your iPhone may use slightly different terminology such as Mobile Service or Mobile Data.
Make sure cellular data is enabled.
If it's off, your iPhone won't use the carrier's mobile-data connection for normal internet access.
Turn it on and test again.
2. Check Airplane Mode
If Airplane Mode is enabled, cellular connectivity is disabled.
Open Control Center and look for the airplane icon.
Or go to:
Settings → Airplane Mode
Make sure it's off.
You can also use Airplane Mode as a quick troubleshooting tool:
- Turn Airplane Mode on.
- Wait several seconds.
- Turn Airplane Mode off.
- Allow your iPhone to reconnect to the cellular network.
- Test cellular data again.
This forces the phone to establish a fresh wireless connection.
3. Look at the Cellular Indicator
Look near the top of the screen.
Depending on your carrier, location, and iPhone, you may see something such as:
- 5G
- 5G+
- 5G UW
- 5G UC
- LTE
- 4G
- 3G
- SOS
- SOS Only
- No Service
This gives us useful information.
If you see 5G or LTE but nothing loads, the phone appears to have cellular service but data isn't working properly.
If you see SOS, SOS Only, or No Service, you're dealing with a more fundamental cellular-network problem.
Our next article addresses that specifically:
What Does SOS Only Mean on iPhone and How Do You Fix It?
4. Check Your Signal Strength
Cellular data depends on your carrier's network.
If you're somewhere with poor coverage, internet access may become:
- Slow
- Intermittent
- Unusable
- Completely unavailable
This commonly happens in:
- Basements
- Elevators
- Parking garages
- Rural areas
- Large buildings
- Tunnels
- Trains
- Remote locations
Move somewhere with better reception and test again.
Cellular Data Works Somewhere Else
That's a strong indication that the original location has a coverage problem.
Your iPhone may be functioning normally.
5. Check Whether Your Carrier Is Experiencing an Outage
Your iPhone cannot connect to a carrier network that isn't functioning.
If possible, ask someone nearby using the same carrier whether their cellular data works.
This is important.
Someone using another carrier isn't a perfect comparison because different providers operate different networks.
If several people on your carrier suddenly lose service in the same area, an outage becomes much more likely.
If you have Wi-Fi access, check your carrier's service-status information.
6. Restart Your iPhone
A temporary cellular or software problem may clear after restarting.
Restart your iPhone normally.
Allow it to reconnect to the carrier network.
Then turn Wi-Fi off temporarily and test cellular data again.
If everything works, stop.
There's no prize for completing all 15 troubleshooting steps after you've already fixed the problem.
7. Check Whether Cellular Data Is Disabled for One App
This is an easy one to miss.
iOS lets you control which apps can use cellular data.
That means:
Safari can work over cellular while another app doesn't.
Open:
Settings → Cellular
Scroll through your applications.
Make sure cellular access is enabled for the app you're having trouble with.
One App Doesn't Work
Investigate that application's cellular permission.
Nothing Works
You're dealing with a broader cellular-data problem.
This distinction matters.
8. Try More Than One App
Don't assume your cellular connection is broken because Instagram won't load.
Try:
- Safari
- Maps
- App Store
- Another internet-dependent app
If everything else works normally, cellular data isn't the likely problem.
The individual application or online service may be experiencing an issue.
Always determine the scope of the failure.
9. Check Your Cellular Plan
Cellular data requires an active carrier account and an appropriate service plan.
Problems can occur if:
- Your account is suspended
- A payment failed
- The line isn't provisioned correctly
- You reached a carrier-imposed data limit
- The plan changed
- The line was recently transferred
- A new SIM or eSIM hasn't activated correctly
If your iPhone settings look normal but cellular service still doesn't work, your carrier account becomes part of the troubleshooting process.
Contact your carrier if necessary.
10. Check Your SIM or eSIM
Your iPhone uses a SIM or eSIM to identify and authenticate your cellular service.
If the line isn't properly recognized, cellular connectivity can fail.
Open:
Settings → Cellular
Make sure your cellular line appears.
If you're using Dual SIM, verify that the correct line is selected for cellular data.
A recent:
- Phone upgrade
- Carrier transfer
- eSIM conversion
- Number port
- SIM replacement
can make provisioning particularly relevant.
If the cellular plan is missing or shows an activation problem, contact your carrier.
11. Dual SIM Users: Check Which Line Is Using Cellular Data
If your iPhone has more than one cellular line, make sure the correct line is selected for data.
Open:
Settings → Cellular → Cellular Data
Review the selected line.
It's entirely possible to have:
Line A working for calls
while:
Line B is configured for data
If Line B has no service or no usable data plan, internet access may fail.
Dual SIM adds flexibility—but also another variable to troubleshoot.
12. Check Data Roaming When Traveling
If you're outside your carrier's normal network or traveling internationally, roaming settings may matter.
Go to your cellular line's settings and review:
Data Roaming
Whether you should enable roaming depends on your carrier and plan.
Important
Don't casually enable international data roaming without understanding your plan.
Depending on your carrier, roaming data can involve additional charges.
If you're traveling and unsure, check with your carrier first.
13. Check Your 5G or LTE Settings
Depending on your carrier and iPhone model, you may have options controlling how the phone uses 5G and LTE.
Open:
Settings → Cellular → Cellular Data Options
The exact options can vary by carrier and device.
If you're experiencing a problem specifically with 5G, testing another available cellular mode can provide useful diagnostic information.
For example:
5G doesn't work, but LTE does.
That's very different from:
No cellular data works at all.
The first points more strongly toward a 5G coverage, carrier, or network issue.
We'll eventually cover this separately in:
iPhone Won't Connect to 5G? Here's What to Check
14. Check for a Carrier Settings Update
Your carrier can provide settings that help your iPhone connect properly to its network.
Connect to Wi-Fi if necessary.
Then open:
Settings → General → About
Wait briefly.
If a carrier settings update is available, your iPhone may prompt you to install it.
Carrier settings can affect cellular network connectivity and related services.
This is particularly worth checking after:
- Changing carriers
- Activating a new iPhone
- Changing SIM/eSIM
- Experiencing unexplained cellular problems
15. Check for an iOS Update
Go to:
Settings → General → Software Update
Review whether an update is available.
Keeping iOS current ensures you have Apple's latest available fixes and compatibility updates for your device.
If cellular problems started immediately after an iOS update, however, don't immediately erase your phone.
Restart it.
Check carrier settings.
Check your carrier.
Check SIM/eSIM provisioning.
Continue diagnosing.
16. Temporarily Disconnect Your VPN
Just like Wi-Fi, cellular data can appear broken when the actual problem is a VPN.
Temporarily disconnect your VPN.
Then test cellular data again.
Everything Immediately Works?
Your carrier connection may have been functioning perfectly.
Investigate:
- VPN application
- VPN server
- VPN configuration
- VPN subscription
- DNS behavior
This is another reason to troubleshoot the entire connection path rather than simply blaming "cellular."
17. Reset Network Settings
If cellular data still doesn't work after basic troubleshooting, consider resetting network settings.
Go to:
Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings
This resets network-related configuration.
It is not the same as erasing the entire iPhone.
However, you'll need to reconnect to Wi-Fi networks afterward, so make sure you know any passwords you'll need.
We don't recommend starting here.
Reset Network Settings makes more sense after you've already checked:
- Cellular Data
- Airplane Mode
- Coverage
- Carrier outage
- SIM/eSIM
- Carrier settings
- VPN
- iOS
Cellular Data Works but It's Extremely Slow
Slow cellular data is different from no cellular data.
Possible causes include:
- Weak signal
- Network congestion
- Carrier throttling
- Poor 5G/LTE coverage
- VPN performance
- Data-plan limitations
- Heavy local network usage
Run the same comparison tests.
Does cellular data become fast in another location?
Does it improve when the VPN is disconnected?
Does another person on the same carrier experience the same slowdown?
Those answers help identify the cause.
Why Does My iPhone Show 5G but the Internet Doesn't Work?
Seeing 5G means your iPhone has established a certain type of connection to the cellular network.
It doesn't guarantee that every part of your internet connection is functioning perfectly.
You could still have:
- Carrier problems
- Network congestion
- VPN problems
- Account problems
- Service outages
The same principle applied to our Wi-Fi article:
A connection indicator isn't proof that the entire path to the internet works.
Why Does LTE Work but 5G Doesn't?
That's excellent diagnostic information.
It means cellular data itself is capable of working.
The problem appears more specific to the 5G connection.
Possible explanations include:
- 5G coverage
- Carrier network conditions
- Provisioning
- Local congestion
- Network configuration
If switching to an available LTE mode temporarily restores reliable data, you have significantly narrowed the problem.
Why Does Cellular Data Work Outside but Not Inside?
Buildings can weaken cellular signals.
Materials such as:
- Concrete
- Metal
- Low-emissivity glass
- Dense walls
can affect wireless reception.
If cellular data works perfectly outside the building but becomes unusable inside, the environment is a major clue.
Use Wi-Fi where available.
Wi-Fi Calling may also help with calls in locations where carrier coverage is weak.
We'll cover that later in:
Wi-Fi Calling Not Working on iPhone? Here's How to Fix It
Why Does Cellular Data Stop Working When I Leave Wi-Fi?
This is one of the most common versions of the problem.
Everything works at home.
You walk outside.
Suddenly nothing loads.
Check:
Settings → Cellular
Make sure Cellular Data is enabled.
Then look at the cellular indicator.
If you have service but no data, continue through the troubleshooting steps above.
If you see SOS Only, move to our next guide.
Why Does Cellular Data Work in Safari but Not an App?
Check the app's cellular permission.
Go to:
Settings → Cellular
Find the application.
Make sure cellular access is enabled.
If it is enabled and Safari works normally, the app itself may be the problem.
Try:
- Closing and reopening it
- Updating it
- Restarting the iPhone
- Checking whether the service is down
Don't reset your cellular network because one app is malfunctioning.
Why Does Cellular Data Work but iMessage Doesn't?
That's another important distinction.
If Safari and other apps have internet access but iMessage doesn't work, your cellular data connection may be completely fine.
Troubleshoot iMessage separately.
Our Connectivity Help section will eventually include:
iMessage Not Activating? Here's How to Fix It
and:
iPhone Not Receiving Text Messages? Here's What to Check
Those are communication-service problems rather than general cellular-data problems.
Why Does My iPhone Say SOS Only?
If you see SOS or SOS Only, your iPhone isn't connected normally to your carrier's cellular network.
Emergency calling capabilities may still be available through supported networks or features, but your regular carrier service isn't functioning normally.
That's a different troubleshooting path.
And conveniently, it's the final article in this batch:
What Does SOS Only Mean on iPhone and How Do You Fix It?
Can Poor Cellular Signal Drain Your iPhone Battery?
Yes, poor cellular conditions can contribute to increased power consumption.
Your iPhone may use additional energy trying to maintain network connectivity in weak coverage areas.
If your battery suddenly seems much worse when:
- Commuting
- Traveling
- Working in a basement
- Entering a large building
- Visiting a poor-coverage area
cellular signal may be contributing.
Our iPhone Battery Help section covers this in:
iPhone Battery Draining Fast? Here's How to Fix It
and:
How to Diagnose iPhone Battery Problems Before Replacing the Battery
This gives us another natural connection between the Battery and Connectivity sections.
Should You Factory Reset Your iPhone?
Not yet.
Cellular data not working isn't enough reason to immediately erase your device.
Before considering a factory reset, determine:
- Does the carrier have an outage?
- Does your account have active data service?
- Is your SIM/eSIM properly provisioned?
- Does another location work?
- Is a VPN involved?
- Are carrier settings current?
- Does Reset Network Settings help?
A carrier provisioning problem won't magically disappear because you deleted all your photos and apps.
Diagnose first.
When Should You Contact Your Carrier?
Contact your carrier when the evidence points toward the cellular account or network.
For example:
- Your line doesn't appear correctly.
- eSIM activation failed.
- You recently changed carriers.
- Your number was recently ported.
- Your account may be suspended.
- Multiple customers are experiencing an outage.
- Cellular service doesn't work despite normal iPhone settings.
- You suspect a provisioning problem.
Your carrier controls the cellular network and service associated with your line.
Some problems simply can't be fixed from the iPhone itself.
When Should You Contact Apple?
Hardware or device-specific troubleshooting becomes more relevant when:
- The carrier confirms your account is properly provisioned.
- Other phones on the same carrier work normally.
- Your SIM/eSIM works elsewhere where applicable.
- Network resets don't help.
- iOS is current.
- The problem follows the iPhone across multiple locations.
- The device has suffered physical or liquid damage.
At that point, professional device diagnosis may be appropriate.
Quick Cellular Data Troubleshooting Checklist
If cellular data isn't working:
- Disconnect from Wi-Fi and test cellular directly.
- Make sure Cellular Data is enabled.
- Check Airplane Mode.
- Look at the cellular indicator.
- Check signal strength.
- Test another location.
- Check for a carrier outage.
- Restart your iPhone.
- Test multiple apps.
- Check per-app cellular permissions.
- Check SIM/eSIM and the selected cellular line.
- Review roaming when traveling.
- Check 5G/LTE configuration.
- Check for carrier settings updates.
- Check for an iOS update.
- Temporarily disconnect VPN.
- Reset Network Settings if necessary.
- Contact your carrier if the evidence points toward the network or account.
The goal isn't to change every setting.
It's to determine where the failure occurs.
Frequently Asked Questions
Why is cellular data not working on my iPhone?
Common causes include Cellular Data being disabled, poor signal, carrier outages, account problems, SIM/eSIM issues, VPN configuration, app permissions, roaming settings, or network configuration.
Why does my iPhone show 5G but nothing loads?
The 5G indicator shows that your iPhone has established a cellular connection, but carrier outages, congestion, VPN issues, account problems, or other network failures can still prevent internet access.
Why does Wi-Fi work but cellular data doesn't?
That indicates the iPhone can access the internet, but something is wrong specifically with the cellular path. Check Cellular Data, carrier coverage, account status, SIM/eSIM, and carrier settings.
Why does cellular work for some apps but not others?
iOS allows cellular access to be disabled for individual apps. Check Settings → Cellular and review the affected application's permission.
Will Reset Network Settings delete my photos?
No. Reset Network Settings is different from erasing the iPhone, although it does reset network-related configuration and you'll need to reconnect to Wi-Fi networks.
Should I enable Data Roaming?
Only when appropriate for your carrier and plan. Roaming can involve additional charges, particularly during international travel.
Why does LTE work but 5G doesn't?
That suggests cellular data itself is functioning and the problem is more specific to 5G coverage, carrier conditions, provisioning, or configuration.
Should I contact Apple or my carrier?
Start with your carrier when the problem involves service, coverage, account provisioning, SIM/eSIM, or an outage. Device-specific problems that persist after carrier issues are eliminated may require Apple support.
Continue With iPhone Connectivity Help
This article is part of the iPhone4Idiots iPhone Connectivity Help section.
Continue with:
- iPhone Won't Connect to Wi-Fi? Here's How to Fix It
- iPhone Wi-Fi Keeps Disconnecting? Try These Fixes
- iPhone Connected to Wi-Fi but No Internet? Here's What to Do
- What Does SOS Only Mean on iPhone and How Do You Fix It?
For related battery problems, visit iPhone Battery Help:
- iPhone Battery Draining Fast? Here's How to Fix It
- 25 Ways to Improve iPhone Battery Life
- How to Diagnose iPhone Battery Problems Before Replacing the Battery
Final Thoughts
When cellular data stops working, don't immediately assume your iPhone is broken.
Cellular connectivity involves several different pieces:
iPhone → SIM/eSIM → Carrier Network → Internet
And your carrier account sits right in the middle of that equation.
Start by determining whether the problem affects one app or everything.
Check whether you have carrier service.
Test another location.
Check your cellular line and account.
Temporarily eliminate things such as VPN configuration.
Only then move toward network resets or hardware troubleshooting.
Most importantly:
Wi-Fi working proves your iPhone can reach the internet. It doesn't prove your cellular connection is working.
Treat Wi-Fi and cellular as separate paths, test them separately, and you'll find the problem much faster.
