[SR-Users] Proxy Registrations offset port

I've been playing with OpenSIPS and am willing to change over if it means I'll get a more informed answer from this community.. I need to set up a proxy forwarding server that can listen on a port other than 5060 ­ I.e. 8080 and forward the registration requests to another Voip platform we have that is running on 5060. I've been able to do this under OpenSIPS but I'm having issues with inbound calls. It could be a NAT issue. Basically listen on 8080 ­ forward any and all registrations to x:5060 ‹ which I've done using rewritehostport Anyone have any good example configs for this? I'm a n00b at this OpenSER stuff ­ but have been around asterisk / freeswitch / portaone for a while. Thanks in advance