Voice Over LTE

4g_mastA few people have been lucky enough to try Voice over LTE (VoLTE) on their cellphones. This is a new application that carries voice calls over the 4G data bandwidth instead of as a separate voice channel as is used for traditional cellular calls.

I say they are lucky, because the quality of VoLTE is much better than the quality of normal cellular calls. This is due to the call being able to handle a wider range of voice frequencies (normal phone calls have always chopped off both lower and higher frequencies, which is why people don’t sound the same on the phone as they do in person). VoLTE is supposed to be close in quality to High Definition voice (HD) which is currently being provided by some landline providers.

VoLTE calls are more akin to a call made on Skype with a quality microphone. If you’ve ever talked to somebody on Skype who was in a boardroom or somewhere with great microphones you will know what I am talking about. You can hear somebody with as rich of a voice sound as talking to them in person. When Skype is not so good it’s mostly due to the crappy microphones in PCs and laptops and not due to the technology.

There are still some significant drawbacks to VoLTE that the industry is working out. Roaming is the biggest issue. Currently, if you are talking on VoLTE and move out of the range of 4G the call will drop. The calls are not downward compatible to 3G or 2G data connections. There is also compatibility issues between carriers since there are still no standards, so you might have trouble talking to somebody using another cellphone provider. AT&T and Verizon are working to make their two networks compatible, but other carriers have not yet been integrated with anybody else. Finally, VoLTE only makes a difference if both callers are talking on VoLTE.

But the major drawback today is one of availability; all of the US carriers have introduced VoLTE only on a trial basis in a few markets. And even where it’s available, it’s only been introduced for a small number of handsets by each carrier. You are more likely going to get to try this first if you use an iPhone or Samsung Galaxy.

Early testers of the technology have made some interesting observations about it. Certainly being able to hear the other party better is a huge benefit. The calls also connect much faster since the call is not making its way through the normal telephone network. One of the most interesting observations is that sometimes you can make VoLTE calls when there isn’t normal cell phone coverage. This is due to the fact that some of the spectrum used to deliver 4G has a larger footprint than the spectrum used to make voice calls.

There are a number of benefits to the carriers of the technology in that it relieves pressure from the spectrum used for voice-only. We’re all familiar with trying to make a call in a stadium or on a freeway at rush hour and not being able to get a signal. But as long as you can get a 4G data connection, even a slow one, you will probably be able to make VoLTE calls.

Calling with the technology is also going to save on cellphone battery life. Today your cellphone spends a lot of energy changing between different frequencies to handle voice and data, or between different types of data.

The technology also supports video calls, which means that it will be easier to have video calls on all phones similar to the  the FaceTime app that comes with iPhones.

Probably the biggest issue with the technology will be how the carriers price it. Callers with small data caps are going to be nervous using VoLTE if it counts against their data plans.

The network owners are working out standards and technologies. Currently, a VoLTE call must be routed back to the switch of the cellular provider before a call can be routed, which is an inelegant network solution. But the industry is working towards a standard called RAVEL (Roaming Architecture for Voice over LTE with Local Breakout) that is going to allow calls to be routed locally when appropriate.

One has to think that eventually this is going to become the voice standard and that the carriers will do away with using a separate frequency for voice. That would allow them to make their networks into 100% data networks and eventually do away with the idea of selling minutes.

There were some field trials of the technology in 2014 and we will be seeing more implementation during 2015. But don’t expect this to be widely available in major markets until 2016 and obviously later in markets that still use 3G.

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