Different Ways To Utilize A Session Border Controller Voice over IP service operators use a session border controller as a kind of controllable access point to their infrastructure. Subscriber calls and other operator calls travel across session border controllers or SBCs. There are different features that SBCs offer, some of which include the following: • • • • • •
Provides a secure connection between an operator and another operator or between an enterprise. Provides operator protection from service attack denials. Controls which calls are accepted or rejected. An operator's VoIP infrastructure internal details are hidden from other users and operators. Checks incoming message content for malicious content. Is compliant for support for legal interception.
A session border controllers features depend on its usage. There are several ways to deploy an SBC, for instance: • User-Network-Interface Session Border Controller • Network-Network-Interface Session Border Controller • Enterprise Session Border Controller Each of these deployment methods have different features needed by a session border controller in order to support the specific scenario. There's generally 3 use cases: 1. On the border between an operator and subscribers. 2. On the border between an operator and an operator. 3. On the borders of an enterprise. Support Features Of Case Session Border Controllers
User-Network Interface In the case of a user network interface SBC, operators use the session border controller to enable a secure border between their VoIP core components and application servers and subscribers. This usage is the oldest case use of session border controllers. The features for this case use would include: NAT traversal, topology hiding, denial of service, overload protection, regulatory features, access control, fraud prevention, interoperability mediation, and capacity. Network-Network-Interface
In the case of Network-Network-Interface SBC, operators are able to establish a secure border to their neighbors with the assistance of SIP based interconnection points. This SBC supports features such as topology hiding, overload protection, limited access control to black and white lists, interoperability mediation, capacity, denial of service, and regulatory features. NAT traversal is not supported in this SBC deployment because there's no dealing with subscribers directly. There is also no need for registration handling. Enterprise In the case of enterprise SBC, the SCBs are used to secure access to the PBX and the communication to the VoIP operator. This SBC will deal will more complex call flows than the other two. This SBC rests on the border of the enterprise network and supports the general SIP specs, the recommendations for connecting enterprises to operators, and the following: NAT traversal, topology hiding (only the contact information of the PBX), overload protection, denial of service, access control, fraud protection, capacity, limited interoperability mediation. Regulatory features should not be expected since enterprises do not offer public services.