A whisper tone is a small announcement associated with a VDN (aka VDN of Origin Announcement). This is different from a zip tone, which is just a quick beep that announces an inbound call.
Unfortunetly, I have no idea how to control the volume of the zip tones (other that to reduce the volume of the entire set, which I don't believe is the answer being looked for.....)
Susan
"A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort."
- Herm Albright (1876 - 1944)