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VoLTE vs. VoIP: What’s The Difference?


When one of our younger engineers recently showed off a new tablet-based app that let him watch television, I shocked him by pointing out that I (the one with the greying hair) had wireless television access as a kid. I was, of course, talking about rabbit-ear antennas and NTSC signals in UHF/VHF bands. In a strange way, the evolution of broadcast television technology had come full circle.

The same is true of telephony. For most of its history, voice was the one and only application. Then came WAP-equipped cellphones that could access packet data. Next came faster, better packet data which led to smartphones hosting Internet-based apps. Finally, with the deployment of LTE the “killer app” that drives IMS deployment is…voice calling.

What is obvious to engineers in the cases of both television and telephony is that, despite the appearance of having come full-circle, the technologies have become incredibly complex over the years. Equally obvious is that end-users don’t care what’s required of engineers: in the case of voice calling, service must be at least as good as it used to be, or the public sees it as a failure.

All of this has led to the deployment of Voice over LTE, or VoLTE. Since LTE is a data-only technology, LTE network operators could handle voice via “fallback” techniques, making use of the still-existing circuit-switched networks. However, some LTE networks offer “carrier grade” digitized voice directly. Conceptually it is Voice-over-IP (VoIP) on LTE, but there is a lot more to it than that. VoLTE vs. VoIP: What’s The Difference?

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The fundamental difference between simple VoIP and VoLTE is that VoLTE requires a Quality-of-Service or QoS component. Typically, over-the-top VoIP applications like Skype and Google Voice rely on the Internet to deliver packets. The problem is that Internet delivery is done on a “best effort” basis; all you can do is get your packets to the cloud and cross your fingers. VoLTE, on the other hand, uses the IP Multimedia Subsystem (IMS) and new radio access network features to ensure low latency, improved error correction in fringe areas, and other features that guarantee voice service as good as or better than any we’ve ever experienced. If all the technology works as planned, even those of us who remember telephones with rotary dials will be amazed at the quality of the calls we’ll be making in the not-too-distant future, as well as the innovative new services that will be bundled with VoLTE.

eBook - VoLTE anf RCS: Getting it Right

Operators are deploying VoLTE and RCS but to be really successful, they must enable a great user experience. Find out how call quality, interoperability, voice handovers to Wi-Fi and VoLTE roaming will impact the customer experience, and how developers can embed innovative applications directly into devices.

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