alright so in playing around with this I realize that my router still had the sip proxy enabled for my other phones which was the key to allowing the mwi to work. It is only when I deactivated that for another issue that I realized that there needs to be some additional configuration required.
So I am back to square one. So I have added the unsolicited line and now I have to figure out next steps.
@Lorne I know you mentioned there are some additional steps, what else is required?
That SIP proxy (Milkfish) on DD-WRT was what I was using to get these Avaya phones working really takes care of quite a lot, so now I have disabled that.