A Session Border Controller (SBC) is a network device that secures voice over IP (VoIP) infrastructures while providing interworking between incompatible signaling messages and media flows (sessions) from end devices or application servers. SBCs are employed in enterprise infrastructures and any carrier network delivering commercial, residential, business, fixed-line, or mobile VoIP services. They are typically deployed at both the network edge and at carrier interconnects, the demarcation points (borders) between their users and other service providers.