Read recommendations and guidelines for cleaning your Apple computer, iPad, iPhone, iPod, display, or peripheral device. 

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.

You may be unable to set the time zone on your iPhone or iPod touch.

This document describes the security content of iOS 5.0.1, which can be downloaded and installed using iTunes.
For the protection of our customers, Apple does not disclose, discuss, or confirm security issues until a full investigation has occurred and any necessary patches or releases are available. To learn more about Apple Product Security, see the Apple Product Security website.
For information about the Apple Product Security PGP Key, see "How to use the Apple Product Security PGP Key."
Where possible, CVE IDs are used to reference the vulnerabilities for further information.
To learn about other Security Updates, see "Apple Security Updates".

These trusted root certificates are preinstalled with iOS 5. When IT administrators create Configuration Profiles for iPhone, iPad,  or iPod touch using the iPhone Configuration Utility, these certificates do not need to be included.