[SR-Users] Issue with INVITE to NATed client

Hi list! I'm using kamailio 4.2 for load-balancing and failover via dispatcher, but I'm having some NAT related issues and I was hoping that someone might point me in the right direction. My setup is the following: PSTN - PBX - kamailio - NAT - client Calls from the NATed client to PSTN and/or PBX features (e.g. voicemail) work just fine. However, when a call comes from PSTN to the client, kamailio sends the INVITE to the client's RFC1918 IP and I can't figure out how to send it to the correct destination. I tried loading the registrar and usrloc modules and used save("location") during REGISTER and lookup("location") just before loose_route(), but the end result was that kamailio replied to REGISTERs with any username/password with a 200 OK and the endpoints never registered with the PBX. I can attach the config file if that will help. Thanks for all input in advance! Regards, Iskren