The Vivox Plugin built directly into the Unreal Engine will be discontinued after Unreal Engine 4.26. The 4.27 Unreal Engine, and newer versions will not include the Vivox Unreal built-in plugin.
However, our downloaded plugin from our Developer Portal will continue to be compatible with newer version of the Unreal Engine even after 4.26. We are planning to release an Unreal Engine 4.27 compatible SDK in an upcoming release. We recommend using the download from our portal in order upgrade to newer version of the SDK when they release.
NOTE: If you are currently using the built-in Unreal Engine plugin, and would like to use the downloadable Vivox plugin, please see our Documentation to learn how to upgrade your project. The guide is location in the following section of our documentation: Vivox Unreal SDK documentation > Vivox Unreal Upgrade Guide > Introduction.