SIP Trunking: Deployment considerations at the network edge.

The move to Voice over IP (VoIP) and Fax over IP (FoIP) in the enterprise has, until relatively recently, been focused on communication within the private enterprise network. Now, some enterprises are using SIP trunks provided by Internet Telephony Service Providers (ITSPs) to connect their internal networks to external, public IP networks. SIP trunking is one of the first steps in an enterprise’s PSTN to VoIP transition, and it enjoys broad availability from service providers in many regions, including many incumbent PSTN service providers.

Adopting a SIP trunking service is not a simple process. In fact, many enterprises need support and guidance as they move to SIP trunking. Enterprises need a way to connect their existing voice infrastructure to SIP trunks without making major changes to their existing voice or data infrastructures. In addition, to provide the necessary protections for the enterprise, there needs to be a mechanism for implementing Network Address Translation (NAT) and firewall traversal, SIP interoperability, and network edge security; as well as a mechanism for providing a clear demarcation point or boundary for real-time IP communication services at the enterprise edge between the external and internal IP networks.

This paper provides an overview of SIP trunking and the benefits it can bring to the enterprise. It also provides information about how to address issues at the enterprise network edge when deploying a SIP trunking service.