This software is not provided or supported by Linden Lab.
This software is provided as-is, without any expressed or implied warranty.
We don't have a vivox redistribution license, but you could copy SLVoice/SLVoice.exe, libortp.dylib/ortp_x64.dll, and libvivoxsdk.dylib/vivoxsdk_64.dll from another viewer to Megapahit's Resources/libexec folder.
On macOS, do not copy the files before you launch the app for the first time, otherwise GateKeeper will fail to verify app integrity and block it from launching.