Since these devices are no longer officially supported for over-the-air updates, you must download the firmware files from reputable third-party archives: IPSW.me

: A comprehensive database of official Apple firmware. You can select your specific model (e.g., iPhone 3GS ) and version to download directly.

Downloading and installing firmware (often called "proshivka") for older Apple devices like the Go to product viewer dialog for this item. iPhone 3GS Go to product viewer dialog for this item.

involves obtaining specialized files. These files are used to restore or update the device's operating system via a computer. Supported Firmware Versions

The maximum supported version depends on your specific hardware:

Apple Iphone 3g - 8gb - Black A1241 (gsm) Ios 4.2.1 Cell Phone Smart eBay - wires_comp Go to product viewer dialog for this item. Can be updated up to . Apple iPhone 3GS - 8 GB - Black (AT&T) Go to product viewer dialog for this item. Can be updated up to iOS 6.1.6 . Where to Download IPSW Files

: Offers direct download links specifically for recovery and restoration files. How to Install the Firmware Download the iPhone 3G iOS IPSW Firmware Restore Files