BANGALORE, INDIA: Matthias Machowinski, directing analyst for enterprise voice and data, Infonetics Research, says: "Many companies have already deployed VoIP internally, but they usually use legacy TDM technologies to connect to the PSTN."

This is according to Infonetics Research's new report, SIP Trunking Deployment Strategies: North American Enterprise Survey, which polled purchase decision-makers at medium and large companies about their use of PBX trunking services. The survey, part of Infonetics' Enterprise VoIP and Unified Communication Continuous Research Service (CRS).

The Session Initiation Protocol (SIP) is a signaling protocol, widely used for controlling multimedia communication sessions such as voice and video calls over Internet Protocol (IP).

"In our latest study, we finally see this changing: SIP trunking is catching up with TDM services and gaining broad traction with buyers, driven by their desire to lower their overall trunking expenditures," Machowinski adds.

He further adds that however, it is unlikely that there will a a rush towards SIP trunking, as SIP trunks are usually implemented during general technology upgrades, which are on hold at many companies right now.

Survey Highlights
The typical survey respondent organization spends between $100 thousand and $500 thousand per year on trunking services.

T1 lines are still the most commonly used trunking service used to connect to the publicly switched telephone network (PSTN), but native VoIP trunks are on the rise.

Thirty nine percent of survey respondents have already deployed SIP trunking, and by 2010, it becomes the second most commonly deployed trunking type.

Respondents are deploying SIP trunking widely across their organizations, and not just trialing at one or a few sites.