Forward incoming calls straight to voicemail

Hi all,
This should be a fairly simply one but i must have missed something obvious as i have not figured it out…

I have a client running FreePBX and Yealink T28P phones. They want to be able to press a button on the reception phone which will forward all calls directly to the receptionists unavailable voicemail. The ring groups are currently setup as a hunt, so the reception phone rings first, then the remaining office phones ring in turn. When DND is enabled on the reception phone, it simply skips this phone and goes to the next. The side keys on the Yealink phones can be programmed to forward to any number, so i tried *808 (reception ext) but it does not work. When forwarding to any external number it works fine.

They do not want it to be automated through time conditions. They need to be able to set it manually.

What am i missing? Any help would be appreciated.

Call flow…Green to ring group, Red to VM. Set BLF key to call flow index usually *28x.

Thanks Bill that worked great. Only thing is the light doesn’t go green or red it just stays off. Is this possible to fix?