Sim failure iPhone 3gs 3.1.3?

just make sure that it's seated properly in the sim card tray. other than that, tell the wireless carrier that you got the sim card from and make sure that they've activated it.

Leigh F said:

I recently got my iPhone unlocked and when I go to put my sim card in it says sim failure, I have tried another sim and it works fine any ideas what's wrong?

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Its absolutely unusual problem . Invalid sim or sim failure indicates that your iPhone 3gs is not unlocked properly . So, re-unlock your iPhone 3gs by using Remote unlocking method . You can get it from any of the online vendors like Unlocking4U.com to unlock it .