: These legacy iOS custom firmware communities often maintain archives of "Time Machine" apps specifically for iOS 3.1.3 and 4.2.1. "Last Compatible" Feature
on Windows 7 to jailbreak 4.2.1 firmware and then manually install archived files via Cydia or similar tools. Archived .ipa Files Viber .ipa for ios 4.2.1
using a tool compatible with iOS 4.2.1.