Cisco Session Border ControlCisco Session Border Control (SBC) is an IP multimedia security and operational enhancement function for session-oriented IP services, based on SIP/H.323/H.248 signaling. It enables direct IP-to-IP interconnect between multiple administrative domains for session-based services, providing protocol internetworking, security, admission control, and management. It enables direct IP-to-IP peering between service providers, and between service providers and their business and residential customers. The most common SBC deployment is Voice over IP (VoIP) peering between service providers by converting IP to public switched telephone network (PSTN) and using existing PSTN peering infrastructure.