But, I don’t seem to get that behavior.  My sngrep graphical flow located here: https://snag.gy/qMWfvk.jpg shows that Kamailio absorbs that negative ACK and then does an INVITE to the media server, which is what I want it to do (because I have a failure route defined)  But, 200 OK from the media server is being passed back to the UA and then the ACK from the UA is being sent to the SIP service versus the media server, which doesn’t make any sense to me.  I must be looking at this wrong.