AT&T is tempering expectations for its forthcoming 5G network riding on sub-6 GHz spectrum. While AT&T says it was the first wireless operator to demonstrate 1 Gb/s and later 2 Gb/s speeds on a commercial 5G network running on millimeter wave (mmWave) spectrum, it’s not making any grand projections for a speed improvement on its forthcoming 5G network running on the lower spectrum bands.

“When we say sub-6 it’s pretty much using the same spectrum that we have today with LTE. So there’s some improvements in spectral efficiency. You’re going to see some marginal differences,” said Igal Elbaz, SVP of wireless technology at AT&T, at an investor conference.

“The real speed boost typically comes with technologies like mmWave and others where you have a significant amount of megahertz that allows you to push a lot of data through that,” he said, declining to put a number on the actual speeds that will be delivered.

When T-Mobile US announced plans to activate its “nationwide” 5G network on 600 MHz early next month, CTO Neville Ray told CNet that the network will generate peak speeds in the range of 200 to 300 Mb/s. That’s roughly 20% of the peak speeds T-Mobile is delivering on its 5G network running on mmWave spectrum in mostly congested urban areas in six U.S. cities.

Spectrum is an important component of 5G, but it’s not the only factor, Elbaz said. “As part of our 5G evolution deployment, we’ve deployed a lot of capacity capabilities such as carrier aggregation, 256 quadrature amplitude modulation (QAM), [and] 4x4 multiple-input multiple-output (MIMO).”

Elbaz declined to say how much spectrum AT&T will commit to 5G and hinted at a need for more mid-band spectrum, but argued that dynamic spectrum sharing (DSS) will overcome at least some of those challenges. “We are starting to test [DSS] now and we’re going to deploy it in 2020,” he said, adding that over time AT&T will be able to use all of its spectrum for 5G.

He also argued that a years-long focus on software and virtualization is providing AT&T with an edge on its 5G strategy and rollout plans.

“5G is the first wireless network that is actually born in the cloud. It’s software defined. The architecture is designed to live in the cloud so that opens up a lot of capabilities,” he said. “The speed that those capabilities are coming is something we’ve never seen before.”

Whenever AT&T places new hardware in the network or touches infrastructure for any reason, it also takes steps to make the equipment 5G ready via software upgrade, he said. Once vendors have 5G software available, AT&T can push that upgrade throughout the network.

“This is what allows us to say that we’re going to be able to launch our sub-6 [GHz] 5G network before the end of the year. This is what allows us to say we’re going to have sub-6 5G nationwide in the first half of 2020,” Elbaz said.

AT&T has deployed 5G in parts of 22 cities on mmWave spectrum and plans to expand that to parts of 30 cities before the end of the year. For now, at least, the high speeds promised by 5G will ride exclusively on that mmWave network.

AT&T has deployed an additional 60 megahertz of spectrum during the last two years and the operator will continue making use of its currently available spectrum across the low, mid, and high bands, he said. There are many open-ended questions about the availability of more mid-band spectrum in the United States and AT&T is keeping an eye on developments, but hasn’t said much beyond that.

“The majority of the operators who have launched with mid-band typically have between 80 to 100 megahertz” of mid-band spectrum for 5G, he said, adding that LTE channels are typically in the range of 20 megahertz. “It really depends [on] what’s going to become available,” Elbaz said.

“5G is much more than just faster networks,” he said, adding that 5G is also ushering in an era of greater efficiency from a capex and operational perspective.

“We are already in a five-year journey in software-defined networking and virtualization. We were the first to start in pushing the industry that way ... and already 65% of our network is virtualized. As we’ve promised publicly many times it’s going to be 75% in 2020. In fact, 75% of the data running through our MPLS tunnels is managed by software,” Elbaz said.

“We feel very confident about this plan. We’re seeing good momentum,” he said. Some of that confidence is fueled by new opportunities in the enterprise space where AT&T has more than 3 million business customers, according to Elbaz.

“One of the big advantages and capabilities that comes with 5G is now you can easily extend your wireless network into an enterprise. We couldn’t do this before,” he said. “There’s a completely new universe of use cases and capabilities that opens up on the enterprise side.”

As AT&T continues to make its case for 5G, the operator is also eyeing a transition to a 5G standalone infrastructure in 2020 and 2021. That’s when it expects chipsets and devices to gain support for the 5G standalone capability.

Elbaz also commented on the state of greenfield networks that are being deployed, such as Dish Network in the United States and Rakuten Mobile in Japan, and how those efforts differentiate from AT&T. “To be honest that’s not much different than what we are doing. We’re doing virtualization and moving to software for the last five years. We have virtualized [the] mobility core for more than 2 years, we’re moving to the cloud, so those capabilities are there,” he said.

“I feel pretty confident in — whether we start from scratch or we’re building on an existing network — the principles of moving to software, moving to cloud, moving to disaggregation, pushing forward the most cost-effective wireless network out there,” he said. “And in fact I really think that we are leading in all of those areas even if we don’t start from a new network from scratch.”