SIP Trunking

Overview

What is SIP Trunking?
SIP (Session Initiation Protocol) is a de facto standard that describes the basic signals used to initiate, manage, and terminate communications sessions. For the non-technical, SIP trunking is somewhat akin to a New York egg cream - a beverage that contains NO egg or any cream! A SIP trunk describes the use of new or existing Internet connection as a replacement for tradition telephone circuits receiving incoming calls and allowing the placement of outgoing calls. Local telephone numbers (normally ten-digit numbers in the US) can be called by people anywhere in the world and ring through to enterprises using public Internet and "SIP trunks." SIP trunks are, in fact, not trunks - dedicated circuits - at all. Rather, the number of SIP trunks that a business requires is determined by the number of simultaneous calls rather than a fixed set of wired connections.

Why is it unique?
It goes beyond voice. It is the industry-backed control standard for multimedia communications or convergence – voice, data, video, and mobile. Because SIP trunks are not fixed in capacity, they can grow rapidly with the needs of the enterprise. In addition, SIP trunks can be delivered anywhere served by sufficient levels of Internet connectivity.

What are the Benefits of SIP Trunking?
Location Independence - Traditional voice is attached to a physical location - SIP VoIP flexibility allows call routing to any IP address worldwide including home offices and soft phones.

Cost Efficiency - SIP trunks are far more cost effective that traditional TDM circuits. A typical small business could easily save 25% or much more on their monthly communications bill.

Pure IP connection - A SIP Trunk is a VoIP trunk that uses SIP for session control and establishes a pure IP connection. This is important for 3 reasons:

1. The VoIP trunk can handle multi-media (voice, data, video and mobile).
2. The circuit-switched hand-off to the PSTN is not needed – lowering costs:
   • Fewer hardware interfaces
   • Fewer PSTN circuits
   • Fewer hardware interfaces to maintain
3. Direct SIP trunking to IP PBXs and soft switches means no additional hardware to achieve end-to-end VoIP.
4. Direct Inward Dialing (DID) numbers can be provided from virtually any location in North America and a large number of other countries. This permits enterprises to establish a "virtual" presence with incoming calls ringing at a centralized facility.