Straight to Voicemail

Leave a voicemail without ringing the phone.

From what I can tell there isn't a way to do this. Our warehouse manager is here way before anyone else and he likes to leave voicemail for people. On our old phones he could just hit 8 and it would go straight to their voicemail instead of waiting for it to ring. Is there a way to do this? Any plans to add this? I'm pretty sure I've seen this feature requested multiple times.