Session Border Controller Benefits
When a user attempts to initiate a voice call or video session, (or other forms of communication, such as instant messaging and presence), across one or more telco networks, SBCs interconnect the networks with appropriate signaling. They ensure these communications are delivered to the right place, in line with pre-set policies, and that traffic is handled in a way that does not put too much strain on the network.
SBCs will often take on some of the core tasks of the network servers in order to route calls based on policy, such as time of day or least-cost-routing, and other services. Number analysis (NA) is another example of a useful SBC function, which determines whether a set of dialed digits represents a valid telephone number (based on number validation, number categorization, or digit manipulation).
In today’s highly unrelated device environment, SBCs are also the key element tying together unified communications systems with new and legacy communications systems such as PBXs (private branch exchanges).
The SBC acts at the session or call level as the translator between end devices, as the intermediary between different network protocols, ensuring interoperability. As more employees opt to work remotely on their own devices this becomes increasingly important. Even something as simple as normalizing a dial plan can be complex, as many legacy PBXs have limited support for how digits can be manipulated. SBCs can manage this call delivery.
Another key function is as one of the primary lines of defense against network intrusions, (hence ‘border controller’). They protect against DoS and DDoS attacks, provide media and signaling encryption, topology hiding, and oversee black, white and grey-listings, ensuring no one can see past the front door to gain information to help plan an attack.
The attack vectors for real time communications such as VoIP and SIP are unique, and data-centric devices aren’t really designed to stop them. In contrast to plain data and TDM voice communications, hacking can be undertaken by intercepting signaling and/or media flowing at any point between two endpoints along the communications path, giving access to other parts of the communications system.
These attacks can take place in many ways. Obtaining confidential information can be achieved by accessing the network under a false identity or eavesdropping on private communications, while toll fraud attacks seek to steal long-distance service by illegally logging onto the network.
As well as guarding against these kind of intrusions SBCs also have extensive roles in billing and disaster recovery. Ultimately, all of the SBC’s functions come down to allowing the service provider to deliver an appropriate QoS level to its customers.