VOX (Dialogic audio)
Also known as: VOX file, Dialogic VOX, .vox audio, voicemail audio
VOX is a low-bitrate audio format using Dialogic ADPCM compression, built for telephony — voicemail, IVR prompts, and call recordings. It is raw audio with no header, so you usually need to know the sample rate to play it correctly.
- Dialogic ADPCM format for telephony
- Headerless raw audio — sample rate must be supplied
- Convert to WAV or MP3 for normal playback
A telephony format
VOX was designed for phone systems, where small files and intelligible speech matter more than high fidelity. It uses Dialogic ADPCM to compress voice heavily, typically at telephone-quality sample rates.
Because the raw format carries no header, the file alone does not state its sample rate — a player has to be told, or it plays back at the wrong speed and pitch.
Opening VOX files
Tools like FFmpeg and Audacity can import VOX if you specify the codec and sample rate. Converting to WAV or MP3 produces a self-describing file that any player opens correctly.