Voice over IP (VoIP) was Viber's flagship feature on smartphones. However, on the J2ME platform, reliable live voice calling was largely unachievable due to lack of hardware access, insufficient processing power for real-time audio codecs, and high network latency. On certain high-end Symbian or BlackBerry devices running J2ME, basic voice functionality was tested, but for the vast majority of standard feature phones, Viber for J2ME functioned primarily as a robust instant messenger. Installation and Compatibility Matrix
Legacy Java ME profiles lacked modern cryptographic standards, making it difficult to implement end-to-end encryption. Viber For Java J2me
Have memories of using Viber on a Java phone? Share your story in the comments (or on the new Viber, from your smartphone). Voice over IP (VoIP) was Viber's flagship feature