Dialogic .vox Format

I need to to create a voicemail prompt file for a phone system. It requires files be formatted as Dialogic VOX, U-Law, 8KHz, 64kbps, Mono but I’m having difficulty finding any options to specifying the vox format settings. Any help would be much appreciated.

Select “other uncompressed files”, then in the options, set the header to “RAW (headerless)” and the encoding to “VOX ADPCM”.
Before you export, ensure that the project is all mono, and the “project rate” (lower left corner of the main Audacity window) is “8000”.