Apple recently seeded a second revision of its iOS 5.0.1 firmware, and besides decrypting key files that aid in the legality of a Siri port, the update seemed to bring nothing new to the table. Some speculated that the second update had something to do with Apple’s continued international rollout of the iPhone 4S.
It turns out that the new iOS 5.0.1 (Build 9A406) is meant to fix SIM-related errors that a limited number of iPhone 4S customers have been experiencing.
According to an Apple support document, revision 2 of iOS 5.0.1 seems to have been intended to fix ‘No SIM Card Installed’ errors that have been affecting a small number of 4S owners.
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.
To fix these issues, Apple recommends backing up your 4S and re-installing the latest version of iOS 5, which is the recently-updated 5.0.1 build. MacRumors notes that there’s been mixed feedback on whether the update actually fixes SIM-related errors or not, with some still getting ‘Invalid SIM’ errors.
Instead of pushing out a 5.0.2 update for everyone, this type of issue would explain why Apple chose to simple substitute a new build of 5.0.1 for the users that needed it. Existing 5.0.1 users don’t need to update, but any user that does try to download the newest version of iOS 5 from iTunes will receive the new 9A406 build. Apple has iOS 5.1 in developer testing.
Have you experienced a similar SIM error on your iPhone 4S? Did installing the new iOS 5.0.1 build help?.