iPhone 4S displays 'No Service' or 'No SIM Card Installed'
Products Affected
iPhone 4S
Symptoms
In certain situations, iPhone 4S may have difficulty recognizing a micro-SIM card, resulting in the following behaviors:
- "Invalid SIM" or "No SIM Card installed" alert appears intermittently.
- Status bar displays "No Service" or "Searching" in a location with good network coverage.
Resolution
If you encounter any of the above symptoms on your iPhone 4S, follow the steps below.
Note: These steps are necessary only if you are experiencing these symptoms on an iPhone 4S.
- Back up your user content and settings using iTunes or iCloud. See this article for more information.
- Restore your iPhone 4S using iTunes.

- After the process is complete, restore your user content and settings from your backup.
- To confirm that you've successfully restored, verify that the version is now iOS 5.0.1 (9A406) in Settings > General > About. If the version displayed is iOS 5.0.1 (9A405), repeat steps 2 through 4.
Additional Information
If you continue to see "No Service" intermittently in the status bar, update your carrier settings.
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