Download iOS 4.2.1 Build 8C148 IPSW Firmware Restore Files
Download the IPSW iOS 4.2.1 (Build 8C148) firmware file released at 18 November 2010 intended to restore iPhone 4 (GSM) via iTunes. IPSW iOS 4.2.1 build 8C148 is unsigned by Apple to update Apple device software.