[Users] OpenSER not sending responses to IP in via header

Hi, I have an OpenSER behind a BIG IP load balancer. The scenario is as follows: 1) The UAC will initiate the call with an INVITE that has the REQ URI set to the IP of the BIG IP. 2) The OpenSER has an alias configured for the IP address of the BIG IP so it receives the incoming INVITE, but when it sends a 100 response, it does not send it to the UAC address that is specified in the VIA header, rather it sends it to the source IP (which is the IP of the BIG IP load balancer). This is undesirable. 3) After the UAS receives the proxied INVITE, it responds with a 100, then answers with a 200. 4) When the OpenSER receives the 100, it forwards this back to the BIG IP load balancer! First, I am surprised that it fowards a 100 at all, and second it is undesirable to send any responses to the BIG IP load balancer since the via header indicates the IP of the UAC. 5) When the OpenSER receives the 200, it forwards it back to the BIG IP also.. again, I don't know why it isn't sending to the IP address of the via - which is that of the UAC. Any suggestions would be most helpful. Here are my related openser.cfg settings: # LOCAL IP ADDRESS AND PORTS listen=65.185.232.62:5061 listen=65.185.232.62:5062 listen=65.185.232.62:5063 # IP ADDRESS AND PORTS OF THE BIG IP LOAD BALANCER alias=65.185.233.104:5061 alias=65.185.233.104:5062 alias=65.185.233.104:5063 thanks, Tim