Embedded voicemail or VM Pro?

If it is embedded, route the incoming lines to a hunt group, with an overflow to another hunt group that contains only a phantom extension that is forwarded to a short code that points it to the auto attendant. (Whew! PM me for specific programming)

If it is VM Pro, route the incoming lines to a hunt group, and enable voicemail. Make a leave action for the VM to route to the AA module.