fixed it myself, maybe.
standard 1:1 natting worked, EXCEPT for VOIP.
tcpdump shows packets going out the right ip, static and all, but the PACKETS (SIP info) contained the wrong 'reply-address' (contained the public ip for the WAN)
I deleted the 1:1 natting for the voip, and entered a manual inbound (portmap) and outbound rule,set them for 'static' and moved the outbound rule above the default manual natting rule.
don't know who or what was messing with the sip packets, but the packets themselves were being rewritten.
(that and I might have gotten it right, but was missing a firewall rule. :-(
Great product, lots of features, but NATTING could use its own book.