"No SIM" (or "No SIM card detected" on Android) means your phone can't find an active line. Either no SIM or eSIM is installed and switched on, or the phone can't read the one that is. "Invalid SIM" means it can read the SIM but won't accept it. Most often the phone is locked to another carrier or the plan isn't active.
Short answer: restart the phone, check the line is turned on in your cellular or SIM settings, then reseat the physical SIM. If that doesn't work, check the carrier lock and try another SIM. If you see "No Service" or "SOS" instead, the SIM is fine and the phone can't reach a network; that's a different fix (below).
Which message are you seeing?
| Message | What it usually means | Start with |
|---|---|---|
| No SIM / No SIM card detected | No active line, or the phone can't read the SIM | Check the line is on, reseat the SIM |
| Invalid SIM | The SIM is read but refused: carrier lock or inactive plan | Check the carrier lock and your plan |
| No Service, Searching or SOS | The SIM is fine, but there's no usable network | See no signal or slow data |
Fixes on iPhone
These follow Apple's own checklist for the "Invalid SIM" and "No SIM" alerts:
- 1Check your plan is active with the carrier or eSIM provider.
- 2Check the carrier lock. Go to Settings → General → About. If the phone is unlocked, Carrier Lock shows "No SIM restrictions". Anything else means it only accepts SIMs from the carrier it's locked to.
- 3Restart the iPhone.
- 4Check for a carrier settings update. Open Settings → General → About and wait a few seconds. If an update is available, a prompt appears; tap Update.
- 5Using an eSIM? Apple's advice is to contact the carrier that issued it.
- 6Using a physical SIM? Remove it, put it back, and make sure the tray closes fully and doesn't feel loose. Apple warns that a tray from a different iPhone model, or from another brand, may not fit properly.
- 7Try a different SIM, or ask your carrier's store to test one. You may need a replacement SIM.
If the alert stays after all of that, Apple says the phone may need service.
Fixes on Google Pixel
From Google's Pixel connectivity help:
- 1Go to Settings → Network & internet → SIMs and select your carrier. If the SIM is inactive, turn on Use SIM. A greyed-out carrier with "No SIM" means there's no active SIM.
- 2Reseat the SIM. Eject the tray with the SIM tool or a paperclip, then check the card. Wipe off dirt with a microfiber cloth; if it's bent or damaged, ask your carrier for a replacement.
- 3Test the SIM in another phone, or another SIM in yours, to see which one is at fault.
- 4Reset mobile network settings under Settings → System → Reset options. Be aware that Reset Bluetooth & Wi-Fi, a separate option on the same screen, deletes your saved Wi-Fi networks.
- 5If the SIM shows an error message, contact your carrier.
Fixes on Samsung Galaxy
From Samsung's "No SIM card detected" guide:
- 1Restart the phone.
- 2Power off, remove the SIM tray and inspect the card for scratches or dirt. Clean the card and tray with a dry cloth, then line the card up properly in the tray.
- 3Reset mobile network settings: Settings → General management → Reset → Reset mobile network settings. This can't be undone.
- 4Test the SIM in another phone. If that phone can't read it either, the SIM is probably damaged; ask your provider for a new one.
- 5Run the SIM test in the Samsung Members app (Support → Phone diagnostics).
- 6If none of that helps, book a repair at a Samsung service centre.
On a trip with a travel eSIM
Travellers usually see "No SIM" in one of a few situations:
- You removed your home SIM and the eSIM line is turned off. With no physical SIM in the tray, a disabled eSIM leaves the phone with no line at all. On iPhone, open Settings → Cellular, tap the travel line and make sure it's turned on. On Pixel, turn on Use SIM for it under Network & internet → SIMs.
- The eSIM was deleted. Check whether it's still listed under your cellular or SIM settings. Most travel eSIMs can't be reinstalled from the same QR code once deleted; see what happens when you delete an eSIM and keep eSIM or erase data before you reset a phone.
- The phone is locked to your home carrier. An eSIM from another provider needs an unlocked phone. Check Carrier Lock as in step 2 above, and look up your model on the compatibility checker.
- The eSIM installed but shows "No Service". That's a network problem, not a SIM problem. Usually data roaming is off on the travel line, or the plan hasn't started yet. See how to turn on data roaming and eSIM not activating.
If your Wanderly eSIM is installed and turned on but still shows "No SIM", contact support from your account with the eSIM's ICCID (how to find it).
When it comes and goes
A "No SIM" message that appears and disappears, especially when you move the phone or it warms up, often points to a worn physical SIM or a loose tray. See do SIM cards go bad? for how to tell.
FAQ
What does "No SIM" mean on my phone? The phone can't find an active SIM or eSIM line. Either none is installed and switched on, or the phone can't read the one that is.
What's the difference between "No SIM" and "Invalid SIM"? With "No SIM" the phone can't find a usable line. With "Invalid SIM" it reads the SIM but refuses it, usually because the phone is carrier-locked or the plan isn't active.
Why does my iPhone say "No SIM" when I use an eSIM? Usually the eSIM line is turned off, it was deleted, or the carrier needs to reissue it. Check Settings → Cellular first; Apple's advice for eSIM problems is to contact the carrier that issued it.
Will resetting network settings delete my eSIM? Resetting mobile network settings clears network configuration. On iPhone, erasing the whole phone asks whether to keep or delete eSIMs, so read keep eSIM or erase data before a full reset.
Can a damaged SIM card cause "No SIM"? Yes. If another phone can't read the card either, it's the SIM; ask your carrier for a replacement.
Does "No SIM" mean my phone is broken? Rarely. Work through the steps above first. If a known-good SIM still isn't detected, the SIM reader may need repair.