January 27, 2011

Migrating to SIP Trunking

Adopting a SIP trunking service is not a simple process. A profusion of choices and decisions awaits you on pricing, service availability, capacity, service level agreements, and much more. That's in addition to selecting the equipment you'll need like SIP-enabled IP-PBXs, session border controllers as well as sizing your SIP trunking implementation correctly.

In fact you may experience a sense of déjà vu as many of the questions you need to ask are those that you already asked (or should have asked!) when replacing TDM with VoIP all those years ago. It's not surprising therefore, that many enterprises need support and guidance. This white paper discusses one of the critical considerations of migrating from TDM to SIP trunks − that of understanding current call activity and volumes across your existing VoIP environment.

The good news is that now you are a few years down the VoIP track, you are in a much better position to understand what to look for and how to find answers. You should now have the tools to analyze and properly assess your VoIP environment, providing valuable information that will position you well to design and negotiate the best rates, contract and service level agreements with carriers and service providers.

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In early implementation stages of VoIP, the primary architecture was to use VoIP for on-net (intracompany) calls and then to hand off everything to the PSTN via TDM-based trunks.

Now we're ready to move forward at "warp speed" into an IP-only environment. And a key component of this is to use SIP as the primary interface to IP-based telephony providers.

This paper provides a great discussion of the processes, challenges, and solutions for making a smooth transition to SIP-Based trunking. Highly recommended!

You’ve chosen a perspective on provisioning and managing SIP trunking which doesn’t get as much coverage as SIP security and NAT translation, edge devices, equipment interoperability and so on. Can you explain what made you interested in writing from this perspective?

As I’ve been writing for a while now about performance monitoring to measure quality, throughput and availability these aspects are always foremost in my mind. I was struck by the amount of good information that’s out there explaining the benefits of using SIP trunks and how it can save businesses money. That’s only really useful if you can size it properly. I thought it would be useful to fill a gap about understanding the current environment before migrating to SIP trunks.

Which of our Webtorials community members do you see as benefiting most from the information in this paper?

Those looking to adopt a SIP trunking service as well as at those who already have one but don’t know if it’s dimensioned properly. For many businesses quite a few years have passed since they first deployed VoIP. For the early adopters it’s a decade or more! They’ll have a lot of decisions to make such as sizing, pricing, implementation and so on. Unless they’ve been tracking their growth and call flows their adoption of SIP trunking may not be as efficient as they expect. Business with lots of branches may well find they are over-trunked, so they need insight into call flows traversing in and out of the infrastructure and plan for any network upgrades or consolidation that may be necessary.

What in particular does Prognosis bring to the table here?

Businesses might plan to dimension SIP trunking for average usage, but how do they know what this is if they’re not measuring it? Voice quality need not be an issue if link provisioning is correct and voice traffic is prioritized, so Prognosis enables voice administrators to understand what to look for and how to find the answers. It provides the means to analyze and properly understand the VoIP environment. This valuable information positions voice administrators well to design and negotiate the best rates, contract and service level agreements with carriers and select the right blend of cost and telephony services.

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