The version of Viber you downloaded might require iOS 4.3 or higher. Double-check the payload info of the .ipa file or search for an older version (e.g., Viber 2.0).
Do not download files from sketchy, ad-ridden software blogs. Use trusted internet preservation repositories: Viber .ipa for ios 4.2.1
This is the most dependable method for devices on such an old iOS version. A jailbreak grants you full access to the iPhone's file system, allowing you to bypass restrictions and install unofficial software. The version of Viber you downloaded might require iOS 4
Apple discontinued support for the iPhone 3G and 3GS (on older bootroms) at iOS 4.2.1 and 6.x respectively. Because of this, the modern App Store does not offer "down-level" compatible apps for these devices. Use trusted internet preservation repositories: This is the
Open Cydia and install . This allows the device to recognize and run unsigned or older .ipa files. 2. Obtain the Legacy IPA
features a built-in store called Time Machine , which hosts pre-configured, working versions of apps like Viber and WhatsApp specifically for the iPhone 3G.