What is a session border controller?

A Session Border Controller (SBC) is a network device used in Voice over IP (VoIP) communications to manage and secure the flow of voice and multimedia sessions. SBCs are typically deployed at the border between different networks, such as between an enterprise and a service provider, to control signaling and media streams. They provide functions such as security, call admission control, protocol interworking, and protection against fraud and malicious attacks. SBCs are essential for ensuring the quality, reliability, and security of VoIP and unified communications systems.