Essentially, SIP trunks are conduits that connect IP PBXes in a manner that Pierce and many others say is more flexible, efficient and cost-effective than legacy options that aren't IP based. SIP trunking – SIP stands for Session Initiation Protocol, the signaling technique used for VoIP and other IP-based applications – enables geographically diverse systems to act as a single entity. Thus, for instance, a multi-location business with VoIP systems linked by SIP trunks can provide features and otherwise treat employees as if they all are in the same physical office.
SIP trunking is growing. Last fall, Infonetics Research offered research suggesting that 39 percent of respondents to a survey said they had deployed SIP trunks, and projected that this year it will become the second most common type of trunk after T1s. The survey was answered by 92 organizations with more than 101 employees.
SIP Trunking's Growth Curve
SNG's Pierce digs deeply into the features and functions of what is available, based on interviews with 10 providers. (A less technical look at the plusses and minuses can be found at Processor.) Pierce doesn't offer a buyer's guide. The goal, which she achieves, is a granular look at the evolution and maturity level of this important category.
The payoff is in Pierce's conclusion:
From the perspective of functionality and reliability, SIP Trunk services are not yet on par with legacy services, so customers should plan on building in a fair amount of resiliency into their SIP-enabled WAN architectures. Business customers often make assumptions about the simplicity or functionality of SIP Trunk services, and expect SIP Trunks to be more mature than most in fact are.
This is an important finding. Pierce suggests that the full value of multi-location UC is most readily realized if SIP trunking enables an all-IP approach. Unfortunately, the technology is not fully baked.