New iOS 5.0.1 Build 9A406 Intended to Fix 'No SIM Card' Errors on iPhone 4S

Yesterday, we noted that Apple had quietly released a tweaked version of iOS 5.0.1. The purpose of the tweak was a mystery given that the update was not being pushed to all users and only made available to those newly updating to iOS 5.0.1. The new version arrived as Build 9A406, and increment of one over the original iOS 5.0.1 release.

But based on a new Apple support document, it now appears that the updated build may have been designed to address an issue some users have been experiencing with SIM card-related errors. With the update affecting a relatively small portion of users, Apple may have elected not to push it out to all users in the form of an iOS 5.0.2 software update, and instead rely on those users who are having problems following Apple's advice and obtaining the new build through the restore process outlined as a solution for the issue.

Last month, some attention was turned on Apple as a quickly-growing thread in Apple's discussion forums revealed a number of users experiencing problems with either a "No Service" or "No SIM Card Installed" warning popping up on their iPhone 4S devices. From Apple's new support document:

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.

Apple goes on to describe the recommended solution for the issue, which involves backing up and then restoring the device, an action that involves iTunes pulling down the new Build 9A406 of iOS 5.0.1 and installing it on the user's device. Once the device's system has been restored, the user can then restore content and settings from a backup.

1. Back up your user content and settings using iTunes or iCloud. See this article for more information.
2. Restore your iPhone 4S using iTunes.
3. After the process is complete, restore your user content and settings from your backup.
4. To confirm that you've successfully restored, verify that the version is now iOS 5.0.1 (9A406) in Settings > General > About.

Unfortunately, user reports on the new build appear to be mixed, with some users reporting that it does indeed fix their "no SIM card" issues while others have seen no improvement. It is unclear at this time exactly why results are mixed and whether the fix addresses only some subset of the root causes of the issue or if some other factor is in play. Consequently, we may have to wait for more users to try applying the update before drawing more specific conclusions.