T-Mobile US stands out among its peers as one of the least vocal proponents of open radio access networks (RAN). It is the only major U.S. operator that hasn’t joined the O-RAN Alliance, a leading coalition of operators and vendors pushing for the disaggregation of network software and hardware running on commoditized gear.

Many leading global operators including Deutsche Telekom, which owns the largest stake in T-Mobile US, are part of the alliance but T-Mobile has consistently kept open RAN outside of its orbit.

“We’re supportive” and “we continue to evaluate” the open RAN space but “it’s going to take some time,” Neville Ray, president of technology at T-Mobile US, said at today’s virtual Big 5G Event.

Open RAN, from his perspective, remains bogged down by many unresolved challenges. T-Mobile US, which is busy working on multiple network upgrade projects that will cost $40 billion during the next three to four years, is content to sit on the sidelines while open RAN goes through a maturation process.

Uncertainty and nagging questions about open RAN’s ability to provide commercial service at scale while meeting heavily regulated requirements is a concern shared by some of Ray’s colleagues, but not all. 

AT&T CTO Andre Fuetsch, one of the industry’s most stalwart supporters of open RAN, recently told Bloomberg that the operator has already added Samsung equipment based on open RAN standards to parts of its network that were previously served by proprietary equipment from Ericsson. 

Enrique Blanco, CTO and CIO at Telefónica, which recently inked a partnership with Rakuten Mobile to collaborate on open RAN, said last week that he expects massive commercial deployments of open RAN to get underway in 2022. He also committed to transition at least 50% of the markets served by Telefónica to open RAN by 2025.

“I think it’s important that the operator community coalesce around open RAN and work through all the pieces that need to be managed,” Ray said at today’s event, adding that there’s still a “couple of big questions” that the operator would like to be addressed. 

“Who’s going to integrate all the pieces?” he said. “If you look at some of the open RAN stacks now and you see the Rakuten model — they’ve been buying integration companies to pull all these pieces together, so it’s challenging to make all that work.”

Rakuten Mobile activated the world’s first fully virtualized, cloud-native open 4G LTE RAN in April, and previously said it plans to deploy 5G service this month. That 4G LTE network arrived six months behind schedule and the operator abruptly delayed its 5G deployment by about three months, blaming supply chain and testing issues tied to the COVID-19 crisis for the delay. 

“The second piece is who’s doing the [research and development]?” Ray said. “And how do you coalesce around maybe five, six vendors on a consistent and common R&D stream, especially as we’re heading into more aggressive feature development on 5G?”

T-Mobile supports open RAN efforts at large, but there are still many issues to work through, he said.

“It’s not a major drive for us right now. Our goal is to push out this 5G network at a real pace with our mid- and low-band spectrum,” he said. “We’ll get to open RAN when the time is right and the opportunity makes sense for us.”