From the SIP Trunking Experts

December 23, 2008

Addressing Interoperability and SIP Trunks

By Steven Johnson President, Ingate Systems, Inc.

This article originally appeared in the December issue of Internet Telephony magazine.
Interoperability is the deciding factor as to whether your SIP trunk deployment will be successful. Perceived to be the most difficult aspect of a SIP trunk deployment, maintaining that balancing act — of having your IP-PBX, service provider and edge device working together seamlessly — can determine whether your SIP trunk is secure, is of good quality, or whether it works at all.

The truth is, deploying a SIP trunk that is fully interoperable is not hard at all. There are important considerations to keep in mind, though, to ensure your installation goes smoothly. Why is interoperability so important? There are several network components to a SIP trunk: the SIP trunking service provider or ITSP offering the SIP trunk service; the SIP-enabled IP-PBX; and the edge device. Since no one vendor provides all three, it is important to make sure these devices can “talk” to one another. If they cannot, then the best-case scenario is that your SIP trunk calls will not go through. Worst case, your network is exposed to potential security threats. It also affects the time it takes to achieve a return on your investment. Purchasing equipment, deploying SIP trunks all take time. The sooner your SIP trunk is up and running, the faster you can realize the significant cost-savings that SIP trunks offer. Here are some steps to ensure interoperability:
Insist on interoperability-tested components: Leading IP-PBXs and ITSPs are aggressively conducting interoperability testing. Making sure the IP-PBX and ITSP are interoperable will smooth the way for an easy deployment. It helps ensure security as well since opportunities for hackers, spoofers etc. are easy to come by when there are inconsistencies between the IP-PBX and ITSP.
Insist on a SIP-based edge device: SIP-based edge devices smooth out interoperability issues. They serve as a “normalization engine” or a universal adapter between the IP-PBX and the ITSP, solving interoperability hiccups before they become a problem. They also add a critical layer of security for VoIP as well as your network, providing inspection, encryption and many other significant protections.
Insist on SIPconnect: The SIP Forum has developed the SIPconnect Technical Recommendation, a standards-based guideline for SIP trunking between IP PBXs and VoIP service provider networks. An increasing number of service providers, PBX vendors and edge device manufacturers are adopting this standard to meet the needs of the growing numbers of customers deploying SIP trunks. Make sure the equipment you purchase adheres to this important standard, which simplifies vendor interoperability.
By taking the time to address interoperability up-front, SIP trunk installations can be a simple and easy process yielding significant cost and other advantages for enterprises of any size.

Steven Johnson is President of Ingate Systems, Inc. To read more of Steven�s articles, please visit his columnist page.

Edited by Greg Galitzine
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