iPhone 3GS SIM Card Not Detected (Searching or No Service) After Downgrade to iOS 4.1
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Cres • February 24, 2013 at 4:50pm
I upgraded my iPhone 3GS from iOS 4.1 to 6.1 but the device entered recovery mode. I used Redsn0w to downgrade it back to 4.1 and jailbroke it, but now my Globe SIM card is not being detected. It constantly shows Searching or No Service. How can I fix this SIM card issue on iOS 4.1?
Answers
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iClarified • January 12, 2026 at 7:25pm
This issue is typically caused by an incompatible baseband version, specifically if the iPad baseband (06.15.00) was previously installed on the iPhone 3GS for unlocking purposes. When you downgrade the firmware but the baseband remains on the iPad version, the device will fail to get a signal. To fix this, you need to use Redsn0w to downgrade the baseband. 1. Open Redsn0w and go to Extras, then Select IPSW and point it to your iOS 4.1 firmware file. 2. Go back to the main menu and click Jailbreak. 3. Select the checkbox that says Downgrade from iPad baseband and uncheck Cydia if it is already installed. 4. Follow the on-screen instructions to enter DFU mode. Once the baseband downgrade is complete, you should be able to install ultrasn0w from Cydia to restore cellular service for your SIM card.
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sarhan • February 24, 2013 at 11:44pm
To fix the Searching or No Service issue on an iPhone 3GS after downgrading, you likely need to address the baseband version. This problem typically occurs if the iPad baseband (06.15.00) was installed for an unlock. You should use Redsn0w to downgrade the baseband. In Redsn0w, go to Extras, select your iOS 4.1 IPSW, then click Jailbreak and check the box for Downgrade from iPad baseband. Once finished, ensure you install ultrasn0w from Cydia to enable service for your SIM card.