We're firmly in the 5G era now, but most phones still have to switch back to 4G or LTE to make calls. That's now changing, as T-Mobile has started rolling out 'Voice over 5G' on select phones.

T-Mobile announced today that it has started rolling out Voice over 5G, also known as VoNR or Voice Over New Radio, in "limited areas of Portland, Ore. and Salt Lake City." The feature is also currently limited to the Samsung Galaxy S21, but it will roll out to more areas and phones (like the Galaxy S22) in the near future. T-Mobile says phones using Voice over 5G will have a shorter delay between dialing a number and the phone starting to ring.

Related: What Is 5G, and How Fast Is It?

So, why does it matter if your phone calls use 5G or not? Well, it mostly just matters to T-Mobile --- the carrier has been building out its 5G network over the past few years, but switching phones back to the older LTE network just for phone calls is a bottleneck on the process. Having everything function over 5G (when a 5G connection is available, anyway) simplifies the technical infrastructure and might result in fewer connection issues for everyone.

The transition also opens the door for 4G and LTE to eventually shut down, though that likely won't happen for at least a decade. T-Mobile just started shutting down its 3G network this year, along with Sprint's legacy CDMA network, both of which were functional for around 20 years.

T-Mobile said in a press release, "The addition of VoNR takes T-Mobile's standalone 5G network to the next level by enabling it to carry voice calls, keeping customers seamlessly connected to 5G. Most importantly, VoNR brings T-Mobile one step closer to truly unleashing its standalone 5G network because it enables advanced capabilities like network slicing that rely on a continuous connection to a 5G core."

Source: T-Mobile