What is a Session Border Controller?
Session Border Controllers, or SBCs for short, are devices/software solutions deployed within VoIP networks and are design to deliver greater control over the various media streams and signalling generated by your business communication channels.
You can imagine SBCs as a firewall for your cloud phone system. As such, SBCs control all the routing to your business phone system and in doing so they ensure both Quality of Service (QoS) and secure all your communication streams.
In order to truly understand what a SBC is, we first need to break down the terminology. In the VoIP industry, when we talk about a Session, we mean the duration of a media stream, i.e. the construction, transmission and break down of data packets within that media stream. For example, in a normal person to person VoIP phone call there are two sessions, one for each person in the call. The session can include multiple media streams including Voice, Video and Data (i.e. Instant Messaging & File Sharing)
The term “Border” refers to boundary where one network ends and the other begins, for example the edge of your corporate network and the outside world. Effectively, what a Session Border Controller does is sit at the border and acts as a checkpoint designed to support system admins ensure the safe and secure flow of information across these border points.
But of course, there’s more to a SBC than simply ensuring the secure border crossing for the media streams. The “Controller” aspect of a SBC is also tasked with managing all the streams in terms of authentication and access control as well as measuring and routing all the connections within their environment.