VoLTE: Where data meets voice

March 28, 2017

As one of the leading vendors of LTE Data Roaming we have established quite a deep understanding of LTE and we get a lot of questions coming through about VoLTE; what it is and how it works. ROCCO reports that over 20% of MNOs will not deliver VoLTE services, which means that the word is not out on whether VoLTE will be a niche or the norm. But incase you are an MNO facing the challenge of deciding whether to support VoLTE, the following might help you to place VoLTE services into the world of roaming.

VoLTE stands for Voice over LTE, but now - what is LTE? Long Term Evolution, which basically means 4G, an enhanced version of the 4th version of wireless technology that is mainly used for data. In case you weren’t aware, almost every time you engage in a call, your signal relapses back to 3G. This is why you can’t simultaneously talk on the phone and surf the internet. And this is where VoLTE comes in.

You’ve probably heard of VoIP (Voice over IP) that facilitates the transmission of voice and multimedia over the internet. Initially, that would’ve been only possible using a computer connected to WiFi, but with the emergence of smartphones, it has become perfectly manageable using your phone. But you still need WiFi. Nowadays, the most common term you would find for VoIP is OTT (Over The Top), which is a term that englobes apps like Skype, Viber, WhatsApp, etc. VoLTE uses the same principle - initiating calls using mobile data only.

In order to avoid the fallback on 3G every time you call and give the already saturated networks a breather, you can now make calls with VoLTE that uses your data, not your minutes. The advantages are many:

+ Superior call quality

A lot more data can be transferred over 4G than 2G or 3G. Some phones may or may not support HD voice.

+ Improved coverage and connectivity

VoLTE is twice as fast as the current methods, and uses a higher frequency allowing for larger distances.

+ Better battery life

We all know how fast the battery evaporates, especially if the network has to switch every time you make a call. 4G to 3G, 3G to 4G. All-the-time 4G calls are simply not supported, at least not on a massive scale.

+ Video calling

4G enables video calling, but has to use your mobile number.

Now, another important difference to establish between LTE and VoLTE is that LTE is hardware based, whereas VoLTE is all software - your phone must be able to support VoLTE in order to make such calls.

But the way VoLTE charges your calls is a bit confusing. The calls use your data, but they are counted as minutes leaving your data intact, and yet others claim it is tied to data only that could make calls more expensive. VoLTE is still a considerably new technology that many MNOs don’t even provide. And in order for VoLTE to work, the phone receiving the call must also support it and essentially, both participants must have 4G coverage during the call. This makes things complicated as 4G is covering only half the globe so far, and is not as widely spread yet even in countries that support it.

HD voice is another component of VoLTE. Many use these terms interchangeably as both give a crystal clear audio quality, but they are not the same thing. VoLTE is the carriage of voice over LTE whereas HD voice is a trade name of a voice codec, AMR Wideband (AMR-WB). HD voice operates also over UMTS and GSM; it is not unique to LTE.

Why didn’t we do this in the first place!? Because originally, 4G did not support calls.

Even though VoLTE has been around for several years, it is still underused and a handful of carriers offer the service (AT&T, Verizon, Orange, etc.). The splendid voice clarity and the promise of longer battery life seem to have everyone asking “Why didn’t we do this in the first place!?” Because originally, 4G did not support calls. With the increasing popularity of OTT apps, mobile operators have made it their mission and vision to bring VoLTE and RCS (Rich Communications Service) to their clients - what a bold way to battle the competition! Some even opine that VoLTE is an important stepping-stone to 5G. But it has been a very slow process. It will be a few more years until those become the norm… and there’s no way of knowing how the companies behind the OTT apps will retort to these improvements. One thing we do know is that they are a lot faster!

MNOs who have established LTE Roaming relationships are working on VoLTE but it requires again testing the service internationally. To date only 10 MNOs have VoLTE Roaming established.

UROS provides high-quality and low-cost global connectivity via an eSIM ecosystem for both static and roaming devices. The solution uses local 4G, 3G and 2G networks to enable smooth connectivity across borders in over 120 countries all over the world. Mostly our MNO clients subscribers are using VoIP services but we are also watching out for VoLTE should the world decide this is the way to go.


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