I finally broke down and put the forwarding in place. I'm not convinced this will fix the specific issue I'm having (a specific number gets VM more than not when calling me - calls don't go to failover, but straight to VM), but it's worth a try. I'm running DD-WRT, which I didn't think was impacted as much as some other routers by this bug. The strange thing is this has only started happening in the last 2 weeks or so. I put a ticket in to see i there's anything odd with the last call where this happened, so we'll see, I guess.