Installing Viber on (common on the iPhone 3G and iPod Touch 2G) is highly challenging because the current version of Rakuten Viber requires iOS 13.4 or later . Technical Limitations & Availability
Conclusion While the desire for a Viber .ipa compatible with iOS 4.2.1 is understandable for users of legacy devices, significant technical, security, and legal obstacles make this impractical for most people. The safest paths are using official App Store mechanisms to obtain older compatible builds tied to your Apple ID or upgrading to a device and OS that receive continued app support. For those willing to accept risks, community archives and jailbreaking may offer routes, but they carry considerable downsides and no guarantee of a working Viber experience due to server-side changes. Viber .ipa for ios 4.2.1