The network layer has traditionally been the piece of the CX stack that nobody wanted to own.
Like the ugly sweater that your auntie bought you for Christmas, you’ve got to keep it, but you stuff it into the back of the wardrobe and try to ignore it.
The network layer equivalent is pushing it off on the telco, moving on, and worrying about the things you can actually control.
However, that attitude is becoming harder to sustain.
AI voice agents are now deployed at scale across platforms like Amazon Connect, Webex, and Genesys – and they have latency requirements that expose weaknesses in legacy infrastructure that contact center teams were never designed to manage.
Simultaneously, BT Openreach's permanent shutdown of the UK's PSTN network in January 2027 is creating a hard deadline that will force enterprises to confront infrastructure decisions they have been quietly deferring.
“This part of the transformation is going to fly under the radar for a lot of companies,” predicts Zeus Kerravala, Principal Analyst at ZK Research.
“They'll probably go through the migration of PSTN to SIP, but not fully understand the implications of what they're getting themselves into.”
The implications, as it turns out, are pretty significant.
Zeus Kerravala shares more of his insights and opinions on the network layer debate in this exclusive interview with CX Today.
Why 800ms Is the Number CX Teams Need to Know
The technical case for why the network layer matters now comes down to latency; specifically, what happens to it when you introduce an LLM into a voice interaction.
Traditional SIP networks were designed for human-to-human calls. A delay of around 200 milliseconds on a human-to-human call is barely noticeable, and both SIP and PSTN networks were built with that tolerance in mind.
The problem starts when an LLM enters the picture. Kerravala explains that the model introduces an additional 200 to 300 milliseconds of processing time on top of existing network latency.
Combined, those numbers start to add up – and when it gets above 800ms, the point at which industry benchmarking suggests AI voice conversations begin to break down, the experience deteriorates quickly enough that customers notice.
“The traditional SIP configurations were designed for human speech,” Kerravala says. “When you start to mix in an LLM, that's when it becomes noticeable.”
From a CX perspective, it can be simplified to this: when a customer says the bot feels slow, somebody has to be able to find out why.
In most organizations right now, nobody owns that problem clearly enough to answer it.
The PSTN Reset: Opportunity or Like-for-Like Swap?
The UK's PSTN shutdown gives this conversation something of a hard deadline.
BT Openreach's permanent switch-off of the traditional copper telephone network lands on January 31, 2027. Every enterprise that is still routing contact center calls over PSTN has to migrate to IP/SIP before that date.
The question is whether enterprises treat that migration as a genuine infrastructure reset or simply replicate what they already have on a newer network.
Kerravala's advice is that “you shouldn't be taking this new technology and making it look like the old technology.”
The PSTN worked the way it did precisely because of its inefficiency. It managed quality through constrained bandwidth – a model that guaranteed a consistent experience but also masked the underlying network's limitations.
Moving to SIP means joining a shared, high-traffic IP network that operates on entirely different principles. The reliability assumptions that CX teams have built their operations around no longer automatically apply.
“If we're going to be running on a network that carries other traffic, more traffic, shared traffic, when a customer says the bot is slow, the CX team has to have the right tools in place to go see why," Kerravala says.
Kerravala’s thoughts are echoed by Forrester's 2026 network infrastructure predictions, which anticipated that business demands from AI systems and conversational AI-powered service desks are now “driving substantial organizational changes” in how enterprises approach network operations – pushing what was previously an IT concern squarely into cross-functional territory.
Kerravala also believes the volume implications could surprise people:
“I've always said that the only interface that we're all born with is voice. If it works well, we're going to use that as the default.”
His prediction is that voice traffic could actually increase in the era of AI agents — which makes getting the infrastructure right more consequential, not less.
The Visibility Gap – and Why CX and IT Need to Work Together
A tool often cited in this conversation is Cisco ThousandEyes, which has been repositioning network observability as a CX capability rather than a pure IT operations concern.
At MWC 2026, Cisco unveiled AgenticOps and broadband assurance innovations specifically aimed at the visibility gap for AI workloads: the problem of understanding performance across the parts of the network an enterprise doesn't directly own or control.
ThousandEyes, Kerravala explains, is one of the few observability tools that can span not just a local network but across the internet – identifying where slowness is occurring, whether it sits in AWS, a carrier network, or somewhere in between.
“We're not troubleshooting CX by looking at a red-green dashboard anymore,” he says.
