Kamailio as Inbound/Outbound proxy or Session Border Controller (SBC)

role of an SBC is to shield the core network from external entities such as user agent’s , carrier network while also providing security , auth and accounting services . In many cases SBC also provides NAT traversal and policy control features ( such as rate limiting , ACL etc ) . In advanced cases transcoding, topology concealment and load balancing is also achievable via a SBC such as Kamailio .