T-Mobile chases voice in 5G - Verizon, AT&T not so much

T-Mobile is pursuing new voice services for its 5G network – and not saying much about it – while Verizon and AT&T appear to be sticking with LTE for the foreseeable future.

To be clear, the carriers aren’t revealing specifics about their playbooks for offering voice services over new 5G technology. They’ve invested a lot in LTE for voice – VoLTE, specifically – and there’s no rush to use a newer technology for making those old-fashioned voice phone calls. But T-Mobile, which is carefully crafting an image as the leader in 5G, both in coverage and technology, appears to be ahead of the pack in voice services based on 5G.

Late last year, T-Mobile President of Technology Neville Ray hinted during an investor conference that T-Mobile would “probably be the first company that drives that” when it comes to 5G voice. At the time, he said “we’re working really hard with our vendors” on Voice over NR. He didn’t mention the vendors, but T-Mobile announced multiple partners leading up to last year’s launch of its 5G Standalone (SA) network, including Ericsson and Nokia.  

In the Non-Standalone (NSA) option that’s used in many early 5G deployments, voice services are provided by the existing 4G VoLTE network, and the 5G connection is used for data only, according to Nokia. In the SA architecture, voice services remain in 5G, along with data services. 

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T-Mobile declined to provide any updates for this article regarding Voice over 5G NR, or VoNR, other than to say they’re “working on it.”

Verizon provided the following statement: “With the strength and extensive coverage of our industry leading 4G network we do not currently see a need for voice over 5G.” Verizon didn’t elaborate on its plans in response to questions from Fierce.

AT&T indicated that it’s in no big rush to share plans for 5G voice either. “We plan to implement VoNR when we believe we can offer a voice experience that rivals our HD Voice capabilities. We haven’t published plans on when it will be commercially available,” the company said in a statement.

5G voice in the wild

Signals Research Group (SRG) recently published a report about tests it conducted of T-Mobile’s network, including its 5G NR SA architecture. SRG founder Michael Thelander told Fierce that they more or less stumbled on 5G voice when testing T-Mobile’s network in southern California.

“Just because we saw this feature in their network, it doesn’t mean they’re close to turning it on,” he said. “It just happens to be enabled in at least some of their markets, and we just got lucky and ran into it. I wouldn’t suggest it’s imminent by any means, but it’s a functionality that they had there” in downtown Los Angeles. “It was more happenstance than anything else.”

It’s not clear what smartphones would even be capable of supporting 5G voice. SRG’s tests used three different smartphones, none of which were Apple devices. SRG’s tests involved the Samsung Galaxy S21 Ultra, the LG Wing and the OnePlus 9 Pro.

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Dramatic improvements in voice quality aren’t expected with 5G, but when a smartphone can remain on 5G when a voice call comes in, that’s an advantage, Thelander said. “If you’re downloading data or uploading data and a call comes in, you want to keep your transaction going on 5G,” he said. 

Many U.S. operators are gearing toward launching VoNR-based commercial voice services using 5G SA by the end of 2021, according to Mavenir Chief Technology and Strategy Officer Bejoy Pankajakshan. T-Mobile “seems to be already using it in n71 [600 MHz] in some” of its markets, he said. Meanwhile, Verizon and AT&T seem to be marching toward their goal of building the 5G SA network with support for VoNR per their 2021 plan, but there’s no confirmation of commercial launches for that.

Mavenir supplies the IMS core components that operators need in their underlying networks before they launch 5G-based voice services. Pankajakshan declined to discuss which operators it’s working with per non-disclosure agreements with customers. But Mavenir is one of the vendors announced for Dish Network, which plans to launch its first greenfield 5G beta market in Las Vegas later this year. Dish is pursuing a cloud native SA core for its network, so it will be using VoNR to provide voice services. The NSA architecture automatically uses LTE at the core.

While 5G voice may not be a priority for all the carriers, it’s definitely on the road map, Thelander said.

Broadly speaking, T-Mobile may be ahead “in terms of putting out press releases and taking credit for things,” and conducting trials is one thing. Actually deploying a commercial service is another, he added.

Still, by and large, T-Mobile has been leading the pack in 5G. “They’re ahead technology-wise when it comes to 5G” and pushing forward, including with the standalone architecture, he said. It’s not too much of a stretch to imagine the “un-carrier” blazing new ground in 5G voice.