What the message actually means
SOS / SOS only
Your carrier connection is unavailable. In the U.S., emergency calls through another carrier’s network may still be possible.
No Service / Searching
The phone is not connected to a cellular network. The label alone does not identify an antenna, SIM, or board fault.
Apple explains these status messages. If you need emergency help, use an available way to reach it now; do not call emergency numbers to test service.
If you have signal bars but only one app cannot use mobile data, check that app under Settings → Cellular. That is a different symptom; Apple’s cellular-data settings guide covers it.
Reconnect, then restart once
Turn Airplane Mode on in Settings for at least 15 seconds, then turn it off. This interrupts cellular calls and data. Retest after the phone reconnects. If service returns, stop here and note whether it fails again in the same location.
If it persists, do a normal restart. Know your passcode first: you will need it after restarting.
Restart directions for your iPhone
- Face ID models: hold either volume button and the side button until the power-off slider appears, then release.
- iPhone 6, 7, 8, SE (2nd/3rd generation): hold the side button for the slider.
- SE (1st generation), iPhone 5 or earlier: use the top button.
Drag the slider, wait 30 seconds, then hold the side or top button until the Apple logo appears. Follow Apple’s illustrated restart instructions if unsure. This is a restart, not an erase.
Retest an ordinary call and a webpage with Wi-Fi briefly off, then restore Wi-Fi. A page loading over Wi-Fi does not show that cellular service recovered.
Check coverage and the account
- Other phones on the same carrier also fail here
- A coverage gap or outage is a useful lead. Check the carrier’s official status or support using Wi-Fi or another phone.
- Your phone works in another known-covered location
- That points toward a location-dependent issue. It does not prove every part of the phone is healthy.
- Only your phone fails across locations
- Ask the carrier to confirm account status, line activation, plan compatibility, and whether the device is blocked before seeking a hardware diagnosis.
These comparisons are clues, not definitive tests. After a transfer, ask whether activation or number porting is complete. Abroad, confirm the roaming plan and possible charges before changing roaming settings. For an iPhone 5s, 5c, or earlier, ask the carrier about network compatibility rather than repeating resets.
Find the affected line
Open Settings → Cellular (called Mobile Service or Mobile Data in some regions). With Dual SIM, select the affected number and check Turn On This Line. If the number is missing, contact the carrier about activation.
For a newly activating eSIM that is listed, Apple recommends turning that line off and back on, then restarting. Stay connected to Wi-Fi for activation help.
Do not tap Delete eSIM or Delete All eSIMs. Apple says to erase an eSIM for troubleshooting only when your carrier directs it. Deletion can require a replacement eSIM from the carrier.
Physical SIM: only reseat it if your model has a tray and you can identify it using Apple’s model illustrations. Use the original tray; do not force it, trim a SIM, or probe other holes. A stuck or damaged tray is a stopping point. Models without a tray use eSIM.
No SIM / Invalid SIM: follow Apple’s separate SIM checklist. After a carrier change, inspect General → About → Carrier Lock; “No SIM restrictions” means unlocked. Ask the carrier to test or replace a physical SIM, or resolve eSIM activation.
Check carrier settings, then iOS
- Connect to Wi-Fi. Open Settings → General → About and follow any carrier-update prompt. Record the Carrier version. No prompt is not proof of hardware damage; see Apple’s carrier-settings instructions.
- Back up important data, then check General → Software Update. Install an offered compatible update using Apple’s update directions, with Wi-Fi and power available.
- Retest the same call and mobile-data checks. Record whether the exact warning changes.
Carrier first. Diagnostics next.
If the carrier confirms the account and network are working but service still fails, arrange assessment. Seek help sooner after a drop, liquid exposure, or repair. For a wet or swollen phone, stop this checklist and follow the safety guides below.
On iOS 18 or later, the latest Apple Support app can run cellular diagnostics. For “Cellular Issue detected”, connect to Wi-Fi, open the app, choose Cellular service → Run Diagnostics, and follow its recommendations. See Apple’s current alert guidance; if diagnostics are unavailable, contact Apple Support.
Before anyone suggests a network reset
Reset Network Settings removes saved networks and non-managed VPN settings, disconnects Wi-Fi, and may turn off roaming. It does not erase photos or apps. Have Wi-Fi credentials available and ask IT first on a managed phone.
Use it only as a deliberate next step with support, not repeatedly. Delete All eSIMs and Erase All Content and Settings are different choices: the latter removes your content. Do not select either as an experiment. A factory restore is not required by this guide.
Sources & scope
Official Apple guidance checked October 9, 2026. Linked instructions support the steps above; comparisons are troubleshooting clues, not bench-test results. This guide cannot confirm a failed component or a carrier outage.
A useful next step
Protect the phone. Keep your data.
Carrier checks complete, still stuck? Send the model and what you observed.