A Session Border Controller is a dedicated network element used to control real-time communication calls/sessions over SIP (Session Initiation Protocol) based VoIP (Voice over Internet Protocol) infrastructures. It protects & governs the IP communication flows, or in simplified terms, governs the manner in which calls are initiated, conducted & terminated over the VoIP network. Furthermore, Session Border Controllers secures enterprises and service provider’s RTC infrastructure.
Types of Session Border Controller
An SBC can be of any type, depending upon your requirements. It comes as a:
• Hardware: dedicated physical equipment installed on your business’s premises.
• Software: a virtual SBC software running on your server.
• Cloud: a cloud-based SBC VoIP solutions for your business.
How a Session Border Controller works
An SBC literally is a wall or a point of demarcation between your enterprise network & the service providers network (the internet). It secures and controls an SIP network by admitting (or not admitting) & directing communications between the internal & external world, such as a VoIP call between two phones or a video collaboration between multiple devices. SBCs deployed at the network perimeter (or border as the name suggests). So that they can control and secure real-time communication sessions for both enterprises and service providers.
Early models of Session Border Controllers were used to protect & control the networks of VoIP service providers, but today it’s used to regulate all kinds of real-time communications in modern businesses. That includes phone calls, instant messaging, video & audio collaboration, & also desktop sharing.
Functions an SBC performs
1. Securing RTC Network
A Session Border Controller protects real-time communications from threats such as toll fraud, DoS attacks (Denial of Service) & spoofing by acting as a Back-to-Back User Agent (B2BUA) & hiding network topology. SBC software also enables encryption of signaling & media to prevent communication tampering. Further, call admission control & dynamic blacklisting of rogue endpoints avoids toll fraud & telephony DoS.
2. Enabling SIP Trunking
As mentioned above, SBC is a demarcation or termination point of the SIP trunk connection in your communications network. It’s more like a SIP firewall that also includes an array of value‐added services like signaling and media interworking, intelligent routing control, resiliency, and high quality of service between different network devices.
3. Interconnecting Networks & Protocols
SBC smoothly performs the interworking & interconnecting tasks, such as dealing with SIP variants & translating protocols, between different networks & the protocols running over them. SIP has a lot of variants; an SBC software can translate these variants between devices so that the calls get through with all their features intact.
4. Session Admission Control
SBC performs session admission control which basically means it inspects & sees who should be allowed to access the network & who shouldn’t. To perform this task, it creates three lists: whitelists, blacklists & greylists. With this task, it maintains the QoS (Quality of Service) on the network.
5. Intelligent Policy & Routing Controls
A policy has a set of rules that defines how the SBC treats different kinds of VoIP events. It allows control of the VoIP signaling and media that passes through the SBC at an application level. We can set multiple policies on a single SBC.
So now, you know what a session border controller is, what are its types & what it does. These are some very basic functions but pertaining to the application of SBC, it might vary for each organization. That’s all you need to get started, but if you want to know more about it, you can take a free demo of REVE SBC. You can check out all its features and then decide if it’s the right choice for your enterprise.