TIME Innovation

Why Your Phone Is Suddenly Making Clearer Calls

VoLTE may be coming to a market near you soon. Here's an explainer to help you make sense of what it means, as well as what it doesn't.

VoLTE: It sounds like “volt,” and it stands for “Voice over LTE.” T-Mobile just announced it was rolling out VoLTE technology out in Seattle, and AT&T’s set to follow with a similar rollout today for areas in Illinois, Indiana, Minnesota and Wisconsin. Verizon’s due to roll the technology out “later this year.” And MetroPCS launched the technology way back in 2012.

But what exactly is VoLTE?

Today’s LTE networks use something called packet-switching, as opposed to the circuit-switching used by older, slower networks. Think of circuit-switching as a highway reserved for a single vehicle from start to endpoint, whereas packet-switching’s more like a giant highway shared by all kinds of vehicles. Without getting into the weeds, LTE networks can’t do voice and data simultaneously: LTE conveys data no problem, but your voice calls actually have to run over the old circuit-switched technology.

VoLTE is thus about bringing voice and data together on the same radio stratum. That’s important for several reasons, one of the most important being the ability, belatedly, for LTE users to do voice and data transactions simultaneously. If you’re an LTE user and you’ve ever tried to talk to someone while sending or receiving emails (technically impossible, unless the data portion’s being sent over Wi-Fi), or you finished a lengthy call only to find dozens of emails simultaneously attacking your mailbox, this probably matters to you.

But VoLTE’s being touted above all else for its ability to enhance the quality of voice calls with what the marketing departments have dubbed “HD Voice.” That’s in part because it’s similar to another acronym you’ve probably heard for years: VoIP, or “voice over IP.” VoIP is what you’re using when you make Skype or FaceTime calls. If you’ve ever made a Skype or FaceTime call and wondered why — when the connection’s solid on both ends, anyway — the audio quality’s so much more nuanced than in a regular voice call, you already have a sense for what’s coming with VoLTE.

The difference between VoLTE and VoIP is that VoLTE employs newer technology designed to guarantee if not infallible voice service, at least better voice service than any we’ve experienced to date.

The hangup — and this is true anytime you’re facing a costly technology overhaul that involves upgrades to your core infrastructure as well as the devices that access it — is that it’s going to take a while before we’re all enjoying VoLTE’s benefits, because older devices aren’t compatible with it. At launch, only T-Mobile users with LG’s G Flex, Samsung’s Galaxy Note 3 or Samsung’s Galaxy Light can access the service (after a software update). On AT&T’s side of the fence, only users with Samsung’s Galaxy S4 mini will enjoy VoLTE for now.

Furthermore, hypothetical VoLTE benefits, like video calls, voicemails and language translation in real-time, are likely a ways down the road. For all the buzz around VoLTE, and I agree wholeheartedly with FierceWireless’ Mike Dano here, it’s more in these initial stages about the carriers playing catchup (while, of course, trying to pass off what they’re doing as more than that) than revolutionizing voice-data tech.

Don’t confuse VoLTE with XLTE, by the way, another term that’s making headlines. XLTE is just the marketing buzz-cronym for a speed upgrade Verizon rolled out a few days ago to several hundred congested markets that lets newer devices hop between spectrums. The new spectrum’s like a brand new highway for those new devices. Devices that can’t use the new highway, meanwhile, enjoy faster speeds by virtue of all those newer devices being redirected to another road.

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