You need to be on a call to use this feature.   Using this feature will transfer a call directly to a user’s voicemail box.  Once on a call:

1. Dial *9 (star, 9) + 3-digit extension and #.
2. The call will go directly the the extension voicemail box and will not ring at the extension.

This feature is useful to use either when you know someone doesn’t want to be disturbed or you know someone isn’t around to answer their phone.