Since the mid-1990s IP telephony has become a widespread means of communication for businesses and service providers. Roughly three-quarters of large companies in the U.S. have already switched to IP telephony, enabling rich-media applications such as collaborative meetings, video, presence-based communication choices, rich hard phone or soft phone displays and end user call control mechanisms. Service provider backbone networks have also largely converted to VoIP transport realizing bandwidth and converged network architecture benefits. Yet TDM trunks are still the predominant mechanism to interconnect businesses with the PSTN (service provider), limiting the inter-business communications to the single-media (voice-only) transport of the traditional PSTN. To realize the promise of VoIP and enable rich-media business-to-business collaborative applications, service providers have in 2008 started offering implementable SIP trunk interconnects. Enterprise interest in SIP trunks for cost benefits, transport benefits as well as new productivity applications have also increased dramatically of late.

SIP Trunks provides an overview of the trends and technologies in evolving PSTN interconnect from TDM to SIP-based transport. It discusses the real benefits and the popular myths surrounding SIP trunks and helps you evaluate what real benefits you could implement for your business. The book provides an in-depth discussion of planning your network for SIP trunk implementation and how to evaluate SIP trunk offerings. Practical guidance around RFP structure is given, including questions to ask the service provider, and providing a sample cost analysis.
It also presents an in-depth discussion of how to deploy SIP trunk interconnects to an enterprise network. The possible deployment models are covered including the trade-offs and network design issues such as security considerations, call admission control and handling new call flows. It offers concrete implementation steps and realistic best practices to follow during the implementation. Network implementation is illustrated with a case study. The book concludes with an overview discussion of the future of unified communications networks and how business transformation due to end-to-end VoIP connectivity (of which SIP trunking is a critical piece) might evolve. This coverage helps the reader visualize how their business might transform over time and how best to plan and prepare their business to capitalize on the benefits.