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SIP Trunking: the Hottest Old Technology


Abstract design of SIP trunking
Image: Maksim Kabakou -
SIP trunking continues to be a hot topic for the No Jitter Enterprise Connect communities, and I’ll admit to having been a bit baffled as to why. If it were a person, SIP trunking would almost be old enough to drink legally. But last week I finally got an answer to the question of SIP trunking’s enduring relevance, and it’s pretty simple: There’s still lots of legacy (i.e., non-SIP) technology out there, and still some new tricks up the SIP trunk providers’ sleeves.
In a webinar sponsored by Twilio, Diane Myers, chief analyst at Omdia, shared data from a recent report on SIP trunking in North America that revealed, as you’d expect, that SIP trunking is now the dominant form of PSTN connectivity. Sixty-seven percent of respondents in the Omdia study reported that they use SIP trunks today, with that share expected to grow to 80% by 2022. In addition, Diane found that SIP trunking represents 68% of the aggregate capacity across all deployed services.
And yet, even as most companies deploy SIP trunks, they still haven’t fully retired their old services. Diane found that 60% of respondents still have T1s or ISDN PRIs in their networks, and while this figure is falling fast, it’s still projected at 39% for 2022.
Why haven’t these enterprises fully migrated away from these legacy services? Basically, if it ain’t broke, they aren’t inclined to fix it. “Companies that have not migrated to SIP trunking cite satisfaction with existing services, security, and reliability concerns” as their reasons, Diane stated in the webinar.
In addition, innovation in SIP trunking continues. As communications platform-as-a-service (CPaaS) players like Twilio have entered the field, they’ve brought greater flexibility and speed to deployment, while UCaaS and CCaaS providers are bundling SIP trunks into their services for a complete offering. So if you were buying SIP trunks from your telco 10 years ago, you still have reason to keep current; it’s not the same market it was a decade ago.
Another data point: For most of its existence, SIP trunking has been a cost play; the savings over legacy PRIs has been substantial. And with some PRIs still left to replace, that’ll continue to be a factor. But in her research, Diane found that enterprise decision-makers cited service flexibility, financial stability of the provider, and reliability as critical factors ahead of cost.
It’ll be interesting to see how the SIP trunking market continues to evolve in the pandemic era, when some enterprises may be reducing the population at their offices, and traffic patterns take on more of a peer-to-peer — i.e., remote worker-to-remote worker — model. However, since enterprises won’t completely abandon large offices or contact center facilities, we won’t see SIP trunking go the way of the PRI anytime soon.
Then again, PRIs aren’t going the way of the PRI as quickly as you’d have thought. Legacy technologies take a long time to die off, and that looks to be the case here as well.