SIP Trunks: Deployments Increasing, But Availability Still LagsSIP Trunks: Deployments Increasing, But Availability Still Lags

In our webinar, we got some new stats from Nemertes Research and some interesting perspectives from Sprint.

In the course of our Enterprise Connect webinar yesterday on WANs for UC and mobility (go here for the replay), we segued into a discussion of SIP trunks. Our analyst presenter, Robin Gareiss of Nemertes Research, presented some data that Nemertes has just released on enterprises' plans around SIP trunks. This chart shows the recent and projected growth among the Nemertes benchmark study base:

It's noteworthy that the number of enterprises that have adopted SIP trunks has more than doubled over the past 2 years, from 12% to more than 31%. It's important to note that this reflects any level of adoption--it could be anything from a single SIP trunk in a single location, on up.

The figure shows that Nemertes is projecting adoption to climb over the 50% mark next year, though interestingly, it looks like it'll level off pretty dramatically at that point.

As we discussed during the webinar, this reflects a growing awareness of the benefits of SIP trunking among enterprises--my anecdotal observations, as well as VoiceCon room counts and No Jitter traffic stats all tell me that no topic draws more interest than SIP trunking. Certainly everybody wants SIP trunks.

Another graphic that Robin showed in yesterday's webinar breaks down the expected adoption trends further:

The blue and yellow slices together make up the 31% figure that we saw for 2010 in the previous chart. And less than 5% report "no plans" for SIP trunk adoption.

So what does all of this mean, and why is the market at the state it's at? We discussed this a bit in yesterday's Webinar.

The big issue is still availability. "The big reason why they're not using SIP trunks is: We just can't get it everywhere we need to go," Robin explained.

Luckily, this webinar also included a service provider representative, Mike McRoberts of Sprint. Mike said that Sprint is pushing a particular approach to SIP trunks, namely centralized access where a single or a few concentrated SIP trunks handle traffic for a multi-site enterprise and then distribute the traffic over the MPLS network to the different sites.

That's an architecture that a lot of enterprises have been attracted to in any event: Among other things, it makes it less of a challenge to deal with the lack of ubiquitous SIP trunk offerings from whoever your carrier may be.

But Mike McRoberts made another point: Taking this approach, you can provision less bandwidth to the concentrated SIP trunk than you would require for individual trunks to all locations. That's because, at least for an enterprise with locations scattered around the country and potentially engaged in different business activities (e.g., retail outlets as well as business offices, warehouses, etc.), you're likely to have different peak busy hours at the different types of locations. If you have individual trunks at each location, you have to provision each trunk for the peak busy hour, but if you're combining all that traffic at one trunk, that one trunk can be provisioned at a lower level than the aggregate individuals, as the peak busy hours even out across the network.

This evening-out effect can drive down the bandwidth requirement by 30%-50%, Mike said. "That translates to real savings," he noted.

Incidentally, Robin offered up overall cost savings figures for SIP trunks that were in line with what we've been hearing all along: She said you can save 20%-60% over PRI by going to SIP trunks.