No Jeff, as I said before, changing outbound proxy online is not an option cause as Dialogic doc says: "...The application can now configure (or reconfigure) the proxy address to use temporarily for routing all future SIP messages on a virtual HMP board basis".
What I need actually in other words is changing proxy on a single call basis.
Simple test situation: I need to make two SIP direct calls to soft phones on two different PCs:
sip:100@192.168.0.199
sip:100@192.168.0.100
Looks like I cannot do that.