The vocoder is available as C source code or as a compiled binary for certain platforms. The source code should compile just about anywhere.
Download the latest version for your operating system/processor:
Windows 95/98/NT/2000/XP with Graphical User Interface (v1.3)
C Source code (v1.3)
Windows 95/98/NT/2000/XP Command-Line (v1.2): Use this version if you are using one of the older front-ends, or want to use the vocoder in batch files. Otherwise, use the above GUI version.
Be OS (x86) (v1.1b1)
Be OS (PPC)(v1.2)
Amiga (680x0) (v1.2)
Amiga (PPC) (v1.2)>
Older versions are available on the download site.
Note that the latest version is not available as a binary for all platforms. This is because I don't run most of these platforms, so any help with compiling binaries would be very much appreciated.