I'm having some problems when using topology hiding. In my scenario an INVITE comes in to the opensips (SBC) instance from another opensips instance (Proxy). It is routed to a callee which eventually answers with a 200OK. The 200 OK is routed through the SBC to the Proxy which answers back with an ACK. This ACK is absorbed by the SBC which (by looking at the logs) attempts to send this ACK to the private IP of the callee instead of the the NAT IP which was originally used for the incoming INVITE.
From the logs I see that right before I attempt to do 'topology_hiding_match()' the 'ruri=public_IP' and after the method is called the ruri switches to 'ruri=private_IP'.
Attached is a trace, the problematic ACK is message number 53. Below is a partial opensips.cfg file I am using with opensips 2.1: