← All Posts October 5, 2026

iPhone Says "No Service", "SOS Only" or "SIM Not Supported": How to Fix It

No bars, SOS in the status bar or a SIM that is refused: these are some of the most common iPhone problems. Here is how to tell a network issue from a carrier lock or a hardware fault.

An iPhone without network is only half a phone. The status bar can show several different messages, and each one points to a different cause:

"No Service" or "Searching…": the iPhone cannot find or connect to the network.
"SOS" or "SOS only": no service from your carrier, but emergency calls are possible through another network.
"No SIM" or "Invalid SIM": the SIM is not detected or is damaged.
"SIM Not Supported": the iPhone is carrier-locked to another operator.

Follow the section that matches your message.

Quick fixes for every case

Airplane Mode: turn it on for 15 seconds, then off.
Restart the iPhone.
Check your area: ask someone on the same carrier if they have signal. Outages happen.
Check your account: an expired plan or unpaid bill can block service.
Update iOS and accept any carrier settings update in Settings > General > About.

"No Service" or "Searching"

Check the cellular settings

Settings > Cellular: Cellular Data must be on, and your line must be turned on if you use two SIMs.
Settings > Cellular > Network Selection: turn Automatic off, wait for the list of networks, select your carrier, then turn Automatic back on.
Settings > Cellular > Cellular Data Options > Voice & Data: try 4G/LTE instead of 5G. Some areas have weak 5G coverage.
When traveling, turn on Data Roaming in Cellular Data Options.

Reset Network Settings

Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. This often fixes persistent "No Service" problems after an update.

"SOS" or "SOS only"

SOS means your carrier's network is not reachable, but another network is. Possible causes: weak coverage, a suspended line, or roaming disabled abroad. If you are in a place where your carrier works normally, contact the carrier: the line may be blocked or the SIM needs to be replaced.

"No SIM" or "Invalid SIM"

Turn off the iPhone, eject the SIM tray with a SIM tool or paperclip, clean the SIM gently with a dry cloth and reinsert it correctly.
Test the SIM in another phone, and another SIM in your iPhone. This tells you whether the SIM or the iPhone is at fault.
Check that the tray is the original one; a bent tray can prevent contact.
For an eSIM, check in Settings > Cellular that the eSIM line is on. If it disappeared after a restore, ask your carrier for a new eSIM QR code.

"SIM Not Supported": the iPhone is carrier-locked

This message means the iPhone was sold locked to a carrier (often a US, UK or Canadian operator) and refuses other SIM cards. Check Settings > General > About > Carrier Lock:

"No SIM restrictions": the iPhone is unlocked. The problem is elsewhere.
Anything else: the iPhone is locked.

The only reliable solution is an official unlock by the original carrier, which Apple then applies on its servers. Carriers usually agree once the phone is paid off. Details in free iPhone unlock: the official way.

About "SIM adapters" (R-SIM, Turbo SIM): these stickers placed on top of the SIM can work temporarily, but they often stop working after an iOS update, can cause network drops, and we do not recommend them.

Could the IMEI be blacklisted?

If a second-hand iPhone shows "No Service" with every SIM, its IMEI may have been reported lost or stolen and blocked by carriers. Ask your carrier to check the IMEI (found in Settings > General > About, or by dialing *#06#). If it is blocked, contact the seller. See how to check a used iPhone before buying.

Hardware: when the modem (baseband) is faulty

If Settings > General > About shows no Modem Firmware version, or IMEI is missing, the modem is not working. This happens after drops, water exposure or board repairs. Try a full restore first (restore guide), then contact a qualified repair center if the problem persists.

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Another model? Browse all iPhone firmware or use the Identifier Lookup tool.

Summary table

Message	Most likely cause	First action
No Service / Searching	Network or settings	Airplane Mode, network selection, Reset Network Settings
SOS only	Carrier unavailable or line blocked	Contact carrier, check roaming
No SIM / Invalid SIM	SIM or tray	Clean and test the SIM elsewhere
SIM Not Supported	Carrier lock	Official unlock from the original carrier
No modem firmware	Hardware	Restore, then repair