ZVD file extension - Zyxel Voicefile (Z-Fax)
What is zvd file? How to open zvd files?
File type specification:
The ZVD file extension is associated with the Zyxel Z-Fax device.
Zyxel Voicefile is audio format used for transferring voice over the Z-Fax a fax and modem devices developed by ZyXEL Communications.
The Z-Fax seems to be obsolete product.