How SBCs Can Simplify the Complexities of Deploying Multi-Tenant SIP Trunks

November 29th, 2012
Ashish Jain, GENBAND’s Director of Solutions Marketing for Session Border Controllers

After more than a decade of deployment history, the session border controller (SBC) is now widely recognized as an essential component in the ongoing transition to an all-IP network. Stationed at the intersections of IP networks, SBCs perform a myriad of tasks to ensure that information carried in SIP sessions -- whether voice, video, presence or IM -- completes its end-to-end journey in a secure and timely fashion.

As the reach of IP communications continues to displace services that were traditionally anchored by TDM equipment, the role of the SBC increases in scope and in sophistication. In addition, as the SBC continues to evolve into a fundamental and vital component of IP communications, the distinctions between competitive products become more acute and more impactful on the fortunes of service providers.

Nowhere is this axiom more in play right now than in the emerging Business Trunking market. Business Trunking (also known as SIP Trunking) is a disruptive technology that enables service providers to offer business customers cost-effective and efficient Public Switched Telephone Network (PSTN) termination and multimedia services by replacing TDM interconnects to PBXs with IP-based connections. IP Business Trunking enables service providers to capitalize on the steady transition to IP in the enterprise market and to offer new multimedia based real-time services to increase ARPU and decrease churn.

One of the most important SBC capabilities relevant to the Business Trunking opportunity is the SBC’s support for multi-tenant deployments. As the term suggests, multi-tenancy defines an SBC’s ability to support and secure the IP communications requirements of multiple enterprises simultaneously. While some enterprises are so large as to justify the service provider dedicating a standalone SBC to a single customer, most enterprises’ SIP Trunking needs require only a fraction of an SBC’s capacity. The service provider that can hone multiple enterprises to a single SBC enjoys significant cost improvements over an SBC-per-customer model.

Most SBCs designed for SIP Trunk deployments offer multi-tenancy through support for virtual IP interfaces (called realms) into the SBC that can be dedicated to each enterprise.  The virtual realms certainly help in segregating the traffic of one enterprise from another but do not assist, for example,  in solving the complexities of quality monitoring or managing SLAs on each enterprise SIP Trunk.

Virtual realms also fall short in delivering other capabilities, such as enforcing common business and network policies, including inbound and outbound trunk capacities, quality thresholds, security rules, fraud alerts, and alarms and events,  across SIP Trunks from multiple branch offices of an enterprise. Relying on realms also makes it difficult for service providers to quickly get access to session-related reports and analytics, CDR details, and traffic behavior of an enterprise for troubleshooting purposes. Last but not least, virtual realms can be too rigid in terms of defining user access privileges or applying administrative policies to an enterprise account.

To overcome these deficiencies, service providers should consider implementing multi-tenancy in SBCs beyond the capabilities offered through realms.  For example, service providers should look for capabilities that allow the partitioning of an SBC (called vSBC) and assign it to a single enterprise or a group of enterprises without compromising the customer-specific capabilities of the standalone SBC.


In other words, each vSBC gets its own dedicated element management system, provisioning interface, policy rule engine, monitoring, reporting & analytics interface and user access management capabilities.  Multi-tenancy allows service providers to assign administrative rights to an enterprise honed to a vSBC without concern that it will compromise the security of an adjacent partition on the SBC.

As they mine the lucrative opportunity that the emerging Business Trunking market presents, service providers will require an IP communications tool kit anchored by an SBC that simultaneously supports their cost efficiency, performance and security requirements. An SBC with flexible and powerful multi-tenant capabilities is just what the Business Trunking-focused service provider ordered. 

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