One of the most important stories of this year's CES, and the recipient of our Best in Show award was a prototype phone from Vivo that showcased the world's first in-display fingerprint scanner. This is a biometric authentication method that could be the best of all worlds, without the need for bulky screen bezels, awkward rear-mounted sensors or complex face detection technology arrays. That prototype was later shipped in China as a X20 Plus UD and now Vivo has brought a concept phone to MWC that represents the next evolution of that idea. It's all about figuring out how to get rid of bezels for good.

The concept phone is called Apex, and its main feature is what Vivo describes as "Half-screen in-display fingerprint scanning technology." The idea here is that instead of placing your finger on a thumbnail-sized icon to unlock the phone, I'll be able to do it on a much larger area of the screen.

In Apex, the usable scanning area is not half the screen, it's more like a third. Or maybe two-fifths. But in any case, the area is large enough to demonstrate the advantage of the technology; this way, you can simply pick up the phone and unlock it without having to think about it. You can also request simultaneous entry from two different fingerprints for added security, or for occasions when you want to protect data shared by two people.

Vivo doesn't say whether the scanner is provided by Synaptics, as was the case with the X20 Plus UD. (I assume it is.) It works the same way, requiring an OLED display and the ability to illuminate the surface of your finger on contact. It's not as fast as a conventional fingerprint reader, and I actually found it works better if you press your thumb against the screen rather than just using the tip. The important thing, however, is that it works.

All of this is in service of the war on bezels that nearly the entire smartphone industry has declared over the past year or so. Apex, as a device, is one of the most aggressive expressions of that ideal so far, with nearly imperceptible bezels around all three sides of the phone and a larger, but still thin, one on the bottom edge. And, as such, Vivo has needed to find solutions for the kind of features that normally require bezels to work.

The most obvious of these is the selfie camera. Some phone makers have gotten around this with notches, others by relocating the camera below the screen so you have to hold the phone upside down. But Apex's answer is ingenious and kind: the 8-megapixel camera is hidden behind the screen and pops up like a periscope when needed. It takes 0.8 seconds to get ready and makes a little buzzing sound. I thought the mechanism would be flimsy, but it actually feels really solid. If nothing else, it's a good way to avoid the notch.

The lack of bezels also means there's no room for a conventional earpiece speaker. Xiaomi's Mi Mix addressed this with a piezoelectric design that worked similarly to bone conduction technology, but Vivo's approach here is to vibrate the entire screen like a speaker: you can still listen to phone calls without holding the device to your head. I've heard better quality calls in my time, but it's totally useful.

Apex is purely a concept, and Vivo says it has no plans to launch an actual product in this particular form. But none of it feels particularly implausible. The fingerprint sensor works, the selfie camera works, the earpiece and speaker work, all in a package with an impressive screen-to-body ratio. I wouldn't be surprised if one, some or all of these ideas make it into various phones in the next year or two, as manufacturers pursue a bezel-free future.