How does SBC Secure a VoIP Communication Network?


VoIP Network is becoming the most needed element in modern business communication. Although there is much cost-effectiveness and convenience associated with VoIP, it has its limitations when it comes to safety. As a communication provider, if you are using VoIP you will need a Session Border Controller (SBC) to mitigate the threats from network-based attacks. A Session Border Controller is also referred to as Class 4 Softswitch or Class 4 Switch. Here are some of the security features of a VoIP Session Border Controller:

Prevention from DDoS Attacks

DdoS Attack

When it comes to security features of an SBC, Distributed denial-of-service (DDoS) protection holds prime importance. An SBC is placed at the edge of your communication network, which is connected to public networks resulting in higher exposure to DDoS attacks.

Attackers try to spoof the source addresses of the target to send requests to a Server Host (i.e. Reflector), that generates a reply toward the target victim which is much bigger than the request message, resulting in a large flood of traffic for the attack. Mentioning DDoS attacks, you should note that attackers use small packet sizes to remain undetected. A VoIP SBC accepts media packets only if they agree to a session negotiated via SIP/SDP signaling.

Traffic Policing

With a Session Border Controller deployed in your network, you can frame policies to receive calls only from your preferred list of users and reject from the unauthorized user list. Traffic Policing identifies malicious attempts by attackers to flood the network.

Topology Hiding with B2BUA

By performing the role of a back-to-back user agent (B2BUA), a Session Border Controller secures a core SIP network and application servers.

B2BUA is a system in which SIP calls are managed by a logical or virtual proxy set up for the call. With the help of B2BU, all signal and media traffic passes through the SBC hiding the topology, or architecture, of the network. This prevents the display of private IP addresses of servers making them less vulnerable to attack.

Media and Signaling Encryption


SBC as a Centralized Codec Transcoding Server

An SBC is responsible for taking care of various types of media traffic along with processing signaling messages. In the process, SBC plays a dual role of securing the media flows along with the application of transcoding where servers and clients do not have a common codec. Encryption is applied by an SBC to both the signaling session initiation protocol (SIP), and media (voice, video, IM, and so on).

A well-structured encryption system means that malicious agents can’t snoop on VoIP calls, media transfers, and other SIP-based communications.

Apart from security, a VoIP Session Border Controller performs other functions like routing and billing. An SBC keeps an eye on the quality of service status for every session, so that calls are lag or jitter-free.

As a VoIP Provider, if you consider security as your top priority, a VoIP SBC is critical in ensuring the same for your network.

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The Author

Abhijeet Guha

Abhijeet is a content marketing professional, who loves to write on various topics related to the telecom industry.
Abhijeet Guha