Amid all the hype around 5G that will dominate the wireless industry’s biggest confab in Barcelona next week, one thing you’re probably not going to hear a lot about is the role of plain old voice in 5G.
Sure, there will be plenty of talk about 5G “calls.” Vodafone, for one, already said it plans to demonstrate a test data call at its stand in Hall 3 throughout Mobile World Congress 2018. It believes its test call with Huawei, which established a data connection, is the first demo to showcase all end-to-end elements of a 5G call, not just data over a 5G connection but also all the control information required to set up the call and route it between 4G and 5G networks.
That follows an announcement by Verizon last week in which the operator used gear provided by Nokia and Qualcomm Technologies to conduct a 4K video stream call using 5G New Radio (5G NR). A voice call could have been accomplished, but they felt a 4K video call was a better way to test and showcase the 5G technology.
Old-fashioned voice calls don't seem to be high on too many agendas, and it’s easy to see why. It's not exactly futuristic. Still, those who are involved in the process of creating standards for 5G say it’s very much a thing and the subject of some philosophical debates as to how it should be deployed in 5G. One thing is for sure: It would be a shame if everyone were to write off voice as a thing of the past, especially when it happens to be making a resurgence in products like Amazon’s Alexa, Apple’s Siri and Google’s assistant.
Voice over LTE (VoLTE) was created as the next-generation IP-based voice service, but it wasn’t exactly easy. Interoperability and the ability to do 911 calls are serious issues and not exactly slam-dunks. But when VoLTE works as advertised in high-def? It sounds like you’re talking to someone in the same room even when they happen to be 10 states or half a world away.
Before we get to voice’s role in 5G, it’s worth taking stock of the status of VoLTE. T-Mobile likes to boast that it was first in the U.S. to deploy VoLTE, and it now has VoLTE on 100% of its LTE network. Currently, more than 80% of all voice traffic at T-Mobile is carried over VoLTE—a global leading stat, according to the company.
Of course, Verizon has VoLTE fully deployed over its network, and 100% of its LTE sites have the capability. Verizon has deployed LTE-only sites for the last few years, so all of those have VoLTE, giving it more coverage than some older voice technologies. (For example, Alaska has only LTE towers—no legacy networks from Verizon.) The vast majority of new devices now come with VoLTE automatically activated out of the box.
AT&T’s VoLTE network now covers more than 320 million POPs, and all the smartphones it has launched since August 2016 have been VoLTE capable, a spokesperson said. The majority of its postpaid customers are on VoLTE-capable devices; its first VoLTE device was the Samsung Galaxy S4 Mini, launched in May 2014. AT&T automatically includes HD Voice for all VoLTE-capable devices for postpaid customers.
Then there’s Sprint, which has been testing VoLTE for more than a year and is preseeding its customer base with VoLTE-capable devices in preparation for a commercial deployment starting this fall. Even without VoLTE, the carrier says that it offers a great HD Voice experience on a very efficient 1x platform, and its goal is to match that experience with VoLTE.
As for 5G and voice, Verizon has not announced any plans for a voice service over 5G, but with 2.56 million miles of the U.S. covered with 4G LTE by Verizon and capable of hosting VoLTE calls, it doesn’t appear to be in any hurry to change that.
Given that the operators have invested a lot of time and money in VoLTE—a technology that frankly I expected would have been deployed much sooner and faster than it actually was—it stands to reason that they’re not in any hurry to concoct a 5G voice service. “I think VoLTE will be there for a very, very long time,” said Nokia’s North American CTO Mike Murphy.
That doesn’t mean it isn’t being considered in the standards bodies. ETSI CTO Adrian Scrase told FierceWirelessTech in a recent interview that there is a desire to not repeat what was done with voice in LTE.
Some discussions are centered around whether voice is considered a separate service or a subset of data. “There are philosophical debates about how we should consider voice, but the overriding principle is we must deliver 5G voice service,” he said. “You can imagine in the standards meetings people saying ‘we mustn’t do what we did with LTE’ where voice sort of got thrown in as a last resort,” he said, noting that there is a 5G work item devoted to voice.
AT&T said that with its initial deployments using the nonstandalone option for 5G, it plans on keeping voice on LTE. “At some point, we will certainly move voice to 5G,” the spokesperson said.
And once voice does come to 5G, what will it look like? It might be more virtual reality (VR) than the plain old phone service referenced above. Manfred Lutzky, head of audio for communications at Fraunhofer IIS, points out that the 3GPP is working on codec technology for multiple audio channels, immersive audio and VR communication use cases.
“We see a trend from one-to-one calls towards multiuser, multiparty conferences—both for plain voice conferences as well as for virtual reality scenarios,” Lutzky said via email. “The EVS developers have already foreseen this trend and improved speech quality in case of multiple speakers in comparison to AMR-WB.”
Fraunhofer expects technology that supports “spherical” video-based calls will become available for 5G voice services. In a spherical video-based call, two parties communicate with each other and experience the feeling of being immersed in the far-end party's environment. For example, one call participant may be calling home from a beach. The call participant at home is able to have a spherical video and audio experience of the beach location, according to the 3GPP.
At Mobile World Congress 2018, SK Telecom will be showing how it plans to evolve its existing Oksusu service, which allows users to chat while watching videos together. Using social VR, it will display virtual avatars of users and their friends and offer the ability to comment on movies they’re watching together.