As the line between voice and data networks continues to blur, a new technology and terminology has surfaced -- SIP trunking.
If you know what VoIP is, you're halfway to understanding SIP trunking -- a frequently misunderstood technology layer that lowers telephony costs while helping enterprises seamlessly communicate.
The term VoIP is typically used to describe the physical equipment that enables Internet-routed voice calls. SIP trunking, however, describes the virtual layer that connects those devices and the larger telephony and data network "clouds." The result is an architecture that links phones, cell phones, mobile devices, desktops, laptops, and any other IP device by bridging the spaces seamlessly across digital networks and traditional PSTN networks between enterprise data networks, analog PSTN phone lines, and larger data networks (e.g., the generic Internet and proprietary carrier networks).
Technically speaking, SIP trunking uses the Session Initiation Protocol (SIP) and Real-time Transport Protocol (RTP) to deliver IP telephony and data traffic across multiple networks. It ensures that local VoIP equipment and IP-PBX switches can connect.
SIP trunking is an enterprise play, requiring robust infrastructure elements that make it secure and reliable for truly end-to-end IP communications. SIP trunking is usually installed by telecom vendors like AT&T, Global Crossing, Verizon, and others.
It's really SIP trunking that enables the grand vision for integrated voice, HD teleconferencing, IM, SMS, MMS, Twitter, IP collaboration tools, and whatever else comes along. The general term for this is Unified Communications (UC).
You can see Google doing this (somewhat) over the Internet with their Gmail, Buzz, Google Voice, Google Talk, Google Docs, and other collaborative applications.
The main reason enterprises caught on to VoIP and SIP trunking early is cost. Economic conditions collided with some technology advances, and early adopters started to rack up savings. Companies realized they were paying too much for legacy PBX equipment, and they noticed the merger of IT and telephony skill sets within their walls. As IT budgets declined or were frozen, the case for all-digital became much more compelling.
One of Gartner Inc. 's latest studies showed 30 percent to 50 percent savings on voice and data connectivity costs for midsized and large enterprises using SIP trunking. That cost reduction comes from a few aspects of the technique:
- End-to-end IP transmissions reduce costs to service providers and their customers.
- SIP trunking terminates calls to the PSTN without the need for customer premise gateway equipment. There's no need to manage and maintain complexities there.
- Peer-to-peer or "on-network" calls that traverse a company's VPN incur no charges (even globally). It's like sending email over the Internet.
- There's no need for separate broadband Internet and PRI (Primary Rate Interface) trunk lines.
- Voice and data network consolidation lowers the cost of connectivity to the service provider network.
- On an end-to-end IP network, there's no difference between interstate and intrastate calling.
In addition, analyst groups are looking closely at how productivity savings from UC will impact budgets and revenue even further. As collaboration and messaging tools become easier to use, people should work more efficiently and communicate more effectively. Companies like Cisco Systems Inc. (Nasdaq: CSCO) (Unified Communications Manager), IBM Corp. (NYSE: IBM)(Converged Communications Services), and Microsoft Corp. (Nasdaq: MSFT) (Office Communications Server) are already trumpeting the value of this communications shift.
One last note: SIP trunking allows companies to keep legacy equipment and transition to all-IP incrementally. This fact alone has gotten the attention of many large enterprises with significant analog telecom equipment investments.
Whether you look at it from a cost or productivity perspective, it's clear that SIP trunking and UC will continue to transform communication in the decade to come.
— Phil Dunn is a journalist, technology consultant, and marketing writer specializing in IT.