How would I set up the follwing phone tree

How would I go about setting up the following menu system:
Caller calls, it rings at the receptionist for 5 rings, then if no pick-up, it goes to the IVR. The problem is, one of the options on the IVR is receptionist. I want it, that if someone chooses that extension, they then have the choice of leaving a voice mail.

Thank you