The Session Controller is the engine that drives your voice-over-Internet Protocol (VoIP) connectivity. It's a real-time network application that uses Layer 5 routing for VoIP connectivity, adhering to the Session Initiation Protocol and H.323 standards. The SC works like any other router in your network, except it's designed to manage VoIP sessions. It will receive a call request from an end user and then route it via a data network to the appropriate destination. Each call request is associated with one of three different types of calls: Setup Call, Hold Call, and Termination Call. The SC can also handle calls from multiple sources at once by accepting various requests at once. A session controller, or session border controller (SBC), is a gateway that manages calls between users and their networks. It's like the bouncer at a club: it makes sure you're who you say you are, then lets you in. The SBC checks the authenticity of incoming calls and routes them to their proper destination. It also authenticates the identity of the person receiving the call and ensures they are who they say they are. The SBC can also manage call signaling and control, which means it can send messages back and forth between two parties to set up a call when one party dials another's number. It handles endpoints and interconnectivity for Internet Protocol (IP) phones, including Session Initiation Protocol (SIP) and H.323 devices. The SBC connects these devices to the network so they can communicate seamlessly. The SBC also provides quality-of-service features such as bandwidth management, which ensures that all calls get equal treatment regardless of how many people may be using the system at any given time, and voice quality assurance. It ensures that all audio signals are clear, and traffic prioritization provides higher priority to certain types of traffic. At the heart of this system is an internal database of all participants involved in each call—that way, it knows where to send each call request!