[Users] Forward response

Hello, Classic situation, overgrown asterisk and need to go openser for load-balancing and failover reasons. We want to do an incremental upgrade to openser, and for the moment we are trying to use openser as a fancy router in front of asterisk. I'm having a little problem with load-balancing the registration. Clients are mostly behind NAT sending registration to openser. I'm using the dispatcher module to load-balance it. The registration is going from the client to the openser, openser is forwarding it to asterisk. Asterisk replies to openser, and that's where I'm stuck. I want openser to forward the "TRYING" and "OK" response (and obviously all other responses) to the client, but can't seem to figure out how. Can anybody point me in the right direction? thanks