AT&T CTO Jeremy Legg said the carrier has “millions” of customers on its 5G standalone (SA) core, highlighting work toward opening up its network assets to new revenue-generating opportunities.

Legg told attendees at this week’s KeyBanc Technology Leadership conference that the carrier’s mobility core is built cloud native and was running in the public cloud. This allows AT&T to layer on services similar to what hyperscalers like Microsoft, Amazon Web Services (AWS), and Google Cloud can offer.

“We're well down the path of that standalone core. We've got millions of subscribers on it already, and we'll continue to ramp that up,” Legg said of the carrier’s 5G SA efforts.

AT&T’s paced 5G SA deployment is common across the carrier ecosystem. Dell’Oro Group recently reported that just 70 mobile network operators have launched 5G SA cores in total, with just five of those being deployed this year.

“Many MNOs already offer 5G SA for enterprises and fixed-wireless access (FWA) but have not yet opened the 5G SA network to consumers; however, they are expected to do so soon,” the research firm explained.

Examples of that pace include domestic carriers T-Mobile US and Boost Mobile both running most if not all of their 5G network functions on a standalone core, while AT&T and Verizon have been slower toward that goal.

Analysts have noted the importance of a 5G SA core toward supporting more advanced network features. This architecture consists of the user plane, control plane, and shared data layer network functions, allowing operators to deliver a more resilient core network and support highly-touted 5G services like network slicing, automation, orchestration, and mobile edge computing.

Legg tied AT&T’s 5G SA moves to the carrier’s broader open architecture migration that includes its open radio access network (RAN) work. This combination will allow the carrier to better monetize those assets.

“Wireless networks have traditionally been very closed, and you can't just plug into a wireless network. [Open RAN] changes that equation and allows people, through SDKs, RDKs (reference design kits) and other software tools to be able to plug into the network and leverage those services,” Legg said.

AT&T’s financial focus

Despite the second word of his title starting with a “t” and not an “f” Legg also noted that AT&T’s push toward more open architectures was driven by vendor consolidation that was impacting broader cost structures.

“One was the economics of it, and it made sense for us to do,” Legg said. “The second was that we thought the networks needed to be open, that ultimately closed network ecosystems generally break down, and you were starting to see that with a lot of the infrastructure providers for these closed networks, there was a lot of consolidation going on in that industry.”

AT&T’s virtualization movement is also allowing the carrier to rip out legacy equipment, further feeding into cost savings. Legg said this progress has resulted in the carrier’s ability to remove “a couple thousand applications that we no longer need.”

“We've modernized much of our infrastructure up in the cloud. We're one of the largest cloud partners that one of the hyperscalers has today,” Legg said in reference to AT&T’s work with Microsoft. “And we're going to rip out our point-of-sale systems. We've already done most of our customer care and call center systems, and those have been replaced.”

Legg provided a verbally ruthless assessment of how AT&T orchestrates a balance of investing just enough into legacy equipment that remains essential while also investing smartly into new technology.

“Isolating the costs associated with the tech debt itself and understanding product-based costing on that legacy infrastructure is essential, and then starving it, making sure that when a new dollar of capital comes in, that you spend the minimal amount possible on that legacy technical debt so that you continue to build the new,” Legg said.

This also ties to employment resources and focus.

It's bifurcating how many people are working on the old stuff versus how many people are working on the new stuff,” Legg said. “The business is going to want to get things out to market as quickly as possible, which may push you toward doing things on the old infrastructure, but you've got to be able to build out the new infrastructure and stay ahead.”

AT&T’s AI progress

Legg also explained that AT&T was seeing significant progress in integrating AI into its operations, noting “we’ve got over 600 models in production across our infrastructure.”

However, the executive said the carrier’s approach toward feeding these models is different from the traditional “Reddit” model used by a lot of companies to train their applications.

“[Reddit doesn’t] have any of our data, they don't have our network data, they don't have our customer data,” Legg said. “So as we've begun to ingest that data into these LLMs [large-language models], we are tuning it for us, and the insights and the data science that we're using are very specific to the kinds of problems that we have.”

One of those is network operations, and “how do we deal with RF (radio frequency) and spectral efficiency.”

“How do we use that in order to remediate issues in the network itself faster,” Legg said. “An example is we've loaded every trouble ticket in the company into our generative and agentic AI frameworks. It now recommends what the fixes are and can write the code to do the fix, and should we just go ahead and automate that. We're still human-in-the-loop there, but these are major, major changes.”

Analysts have pointed to the benefits AI can bring to the deployment and management of cloud-based open RAN networks, which are more complex orchestration challenges due to the disaggregated multivendor ecosystem. The use of AI could help close performance gaps for open RAN architectures compared with legacy RAN models.