Here's our work-around.
Extension 210 = Physical phone
Extension 310 = DR for that person's extension
Person dials extension 210. Fallback options are to go to DR 310 if no answer after 15 seconds or if busy.
DR 310 says "Press 1 to reach **** on his cellular, Press 2 to speak with the receptionist, Press 3 to leave a message for ****"
Person presses 3, DR redirects right into that person's voicemail.