Session border controller definition
A session border controller (SBC) is a network device that manages voice, video, and messaging communications over IP networks, ensuring that they are safe and private. It's specifically designed to handle session initiation protocol (SIP) traffic. Network devices and applications use SIP to initiate, maintain, and terminate real-time sessions involving video and voice calls and written messages.
See also: VoIP, VoIP gateway, session control protocol, IP network
How session border controller works
Here's what SBC does:
- Traffic management. SBCs sit at the edge of networks, where they regulate the flow of SIP traffic between the internal network and the external world (it could be just another network or the whole internet). They control how calls are initiated, conducted, and finished, making sure that communication is smooth and efficient.
- Security. One of the primary functions of an SBC is to secure the communications passing through it. It can authenticate and authorize sessions, encrypt data, and hide the details of the network's internal structure from the outside world. SBCs protect the network from denial of service attacks, fraud, and eavesdropping.
- Ensuring compatibility. Different networks and devices often use different protocols or versions of SIP. SBCs mediate between these differences, translating or adapting protocols as necessary to make sure that devices and networks can communicate with each other without compatibility issues. This is a crucial feature because of the very diverse and complex digital communications environment.
- Quality of service. SBCs monitor and manage the quality of calls and other communications, ensuring that data packets are prioritized correctly so voice calls and video streams are always high quality and without interruptions. This includes managing bandwidth, mitigating packet loss, and compensating for jitter and latency.
- Call routing and policy management. SBCs also handle the routing of calls based on predefined rules and policies. It can include selecting the most efficient path for the call to travel through the network, enforcing call admission control policies to prevent network overload, and implementing rules for regulatory compliance.
- Media handling. Beyond just dealing with SIP signaling, SBCs also manage the audio and video streams associated with these communications. They can adjust media flows for better performance, convert between different media formats, and support features like media encryption.
