What is a Session Border Controller (SBC)?

A Session Border Controller (SBC) is a specialized device or software application that is deployed in a VoIP network to control and secure real-time communication flows. In simple terms, you can think of it as an advanced firewall specifically designed for your phone system. It sits at the "border" of your network, managing all the communication traffic that enters or leaves.

To fully understand its role, it's helpful to break down the name:

• Session: In telecommunications, a "session" refers to any real-time communication exchange from start to finish. This includes the setup, the actual conversation (which can be a media stream of voice, video, or instant messaging), and the termination of the connection. A simple phone call involves at least two such sessions.
• Border: This refers to the boundary point between two different networks. Most commonly, this is the edge where your private corporate network connects to the public internet, where your service provider's network begins.
• Controller: This is the core function of the SBC. It actively manages and exerts control over all the sessions that cross the border.