In a distributed SIP trunk deployment model, each corporate site has routed connectivity to the corporate private WAN. Each site will have direct SIP session connectivity to the IP PSTN as shown in figure 1 . This connectivity can be achieved over the same physical connection when one service provider provides both private WAN (typically MPLS-based) and the SIP trunk session connections.

In this model the SBC is deployed both in the headquarters and the branch offices. In a private network the foremost issue is the security risk of attacks on infrastructure from inside the enterprise network. Another problem in a distributed model is incompatibility issues due to use of IP PBXs from multiple vendors which do not interwork. RibbonSBCs deployed in the private network borders protects and controls the private enterprise borders from internal security risks and incompatibility issues.

Figure 1: Distributed SIP Trunk Model

With distributed SIP trunk model, advantages include:

  • SIP trunk session capacity changed to the requirements of each remote site, even allowing different levels of session capacity per site depending on many factors like user registration or time zone.
  • Optimizing bandwidth depending on each site.
  • QoS and CAC capabilities are handled at each site.

Load on the private WAN/MPLS is reduced due to elimination of much of media traffic between remote locations and the corporate site.