Apple has released iOS 4.01 which can be downloaded for free via iTunes by simply connecting your iPhone to your computer or simply click the Refresh button located in the Summary section of your iPhone in iTunes. This update contains bugs fixes and improvements, including the formula to determine how many bars of signal strength to display. iOS 4.0.1 is compatible with all iPhones with the exception of the first model EDGE (2007).
How to install iOS 4.0.1 update:
- Upgrade your iTunes version to 9.2.
- Back up your data before running the install, so plug in your iOS device via USB and hit Sync.
- When you’re done syncing, click Check for Update.
- Download iOS 4.0.1, then follow the on-screen instructions to install.
Download iOS 4.0.1 Firmware (Official Links)
To download and install iOS 4.0.1 firmware on your iPhone and iPod Touch use the following link: