It would appear that part of the problem is that using extension 221 in a hunt group automatically routes the call back to the VM menu.

So I create a hunt group 1, DN 290, with members 222 and 223, which rings both phones. If I set up overflow for hunt group 1 to 222, and CFNA for 222 is pointing to the voicemail DN, and overflow is triggered and the call is routed to 222, does the CFNA setting for 222 apply to that routed call ?