How voice calls could move beyond smart watches into a range of wearables

Next month will be the third anniversary of Samsung Gear smartwatch, one of the first mass-market wearables with phone capabilities. We’ve since seen two successor devices from Samsung as well as several Android Wear watches with voice capabilities, and most recently, the Apple Watch Series 3 with LTE.

I’ve been using the latter for nearly two weeks, having purchased one. I’ve also tested many of the Samsung and Android Wear devices over the past few years. Throughout all of these experiences, one thing is becoming clear to me: The decoupling of voice calls from actual phones is gaining momentum and it’s quite liberating. I don’t have to worry about carrying (or dropping) an expensive phone when leaving the house to walk the dog or run errands. This connected freedom, combined with technology advances can lead to brand new opportunities for future wearables of every shape, size and budget.

Before looking to the future though, it makes sense to look back in the past. How did we get to where the “Dick Tracy communicator” is essentially now a reality? The short answer: radical evolution in chip, radio, network and other technologies.

Smaller and faster “things” over the past 25 years

For example, the current state of taking phone calls on the wrist couldn’t happen without the gradually disappearing SIM card. You may not remember what SIM cards looked like in the early 1990’s so let me refresh your memory. Take a credit card out of your wallet. Go ahead, I’ll wait. Got it? Good. The first SIM card I had in my mobile phone was exactly the same size as what you have in your hand and had a surface area of 3,512 square millimeters.

It truly was a “card” although only a small part of it had the electrical circuits to store subscriber information and contacts. In 1996, we saw the useless plastic card go away, leaving just the gold circuitry, but even that was big by today’s standards. Seven years later, the micro-SIM appeared, making the module even smaller. Then in 2012, the nano-SIM used in most phones today arrived, but even these take up more space than necessary in a wearable device, so the industry has turned to embedded-SIMs, or e-SIMs for today’s voice-enabled wearable devices. These e-SIMs measure 5 mm x 6 mm, or 30 square millimeters, which is 100x less area than the first SIM cards.

Even as the SIM cards for voice devices got smaller, our mobile broadband networks became faster. Fifteen years ago, I thought the EVDO cellular modem I used was blazing fast. And compared to prior wireless technologies, it was.  At roughly 2 to 3 Mbps. Now, we’re hearing about Gigabit-capable networks — that’s 1,000 Mbps — phones and tablets, or roughly a 500x increase in transfer speeds.

I’m sure I don’t need to illustrate the advances in mobile chips in detail, but for a simple example, Apple’s touts its new A11 Bionic chip in the iPhone 8, 8 Plus and X phones as 70 percent faster than its predecessor, the A10 Fusion. And according to Apple, the 2016 A10 Fusion is 120 times quicker than the chip in the original 2007 iPhone.

Everything we need for voice calls in wearables is here

Add all these developments up and combine them with other recent evolutionary ideas and you have the perfect storm for bringing voice calls to any number of form factors.

For example, moving voice from traditional cellular technology to VoLTE, or Voice over LTE, completes the “voice is just another form of data” transition. And even though many mobile broadband networks are blazing fast (and getting faster) you don’t need much bandwidth, i.e.: throughput speed for VoLTE calls. Using a new codec — capable of HD Voice quality — a call only needs about 49 kbps of bandwidth: 24 kbps for the voice information and the remainder for overhead. Note, that’s not Megabits per second, but kilobits per second.

That reminds of me of the often minimal bandwidth requirements for today’s IoT devices. These don’t send gobs of data through the internet like web pages and video streams on a phone, tablet or connected TV. Instead, small bits of information, often only when there’s actually information to send or receive. Indeed, we have new networks just for the internet of things that use much less bandwidth than our mobile devices. Think CAT-M1, Sigfox and narrowband IoT, or NB-IoT networks. It makes me wonder if we eventually see mobile “slowband” networks just for VoLTE and/or messaging wearables in the future.

Of course, the more devices that can handle phone calls, the more phone numbers we might have, right? Nope, that obstacle is going away too thanks to advanced call forwarding and number linking carrier services. My Apple Watch does have its own unique phone number, but it’s tied to my main T-Mobile phone number. T-Mobile calls their number linking service Digits, while AT&T has NumberSync; other carriers have their own branded solutions.

What are the remaining challenges?

New networks aside, there are still some issues to tackle before we see wearable communicators in various form factors similar to today’s Bluetooth headphones, fashionable connected jewelry and other devices we put on instead of carrying around.

First and foremost is battery life. That’s the one technology that has made the least progress relative to everything else in a voice call wearable.

Currently, using the Apple Watch for voice calls roughly drains the battery by 1 percent per minute in my testing, so there’s more work to be done here. Some of this challenge could be mitigated by application specific processors that are engineered for efficiency of a given task such as voice calls. Frankly, it doesn’t take much processing power to run the basics of a cellular phone these days. Nor would the chip need to be large. The S3 and W2 system on a chip in the Apple Watch Series 3 with LTE isn’t much bigger than the e-SIM, for example.

Then there’s the need for an antenna to stay connected to an LTE network. Apple has wrapped the antenna of the Apple Watch Series 3 around the edge of the display. It works well, but we’ll need smaller amplified antennas if we want smaller wearables with voice capabilities.

Once those two challenges are mitigated however, you might be able to leave your phone behind and simply take calls from a fashionable bracelet, your glasses or some other everyday device similar to today’s headphones that can store music for playback and just leave the phone behind. After all, not everyone wears a watch.